Colored light has been used as a treatment modality for physical and ... psychophysiological response between exposure to red or blue light, the small sample.
PHYSIOLOGICAL AND PSYCHOLOGICAL RESPONSE TO COLORED LIGHT
A dissertation presented to the Faculty of Saybrook Graduate School and Research Center in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Ph.D.) in Psychology by Larry Mark Honig
San Francisco, California 2007
UMI Number: 3369590 Copyright 2009 by Honig, Larry Mark All rights reserved
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ii Abstract
PHYSIOLOGICAL AND PSYCHOLOGICAL RESPONSE TO COLORED LIGHT
Larry Mark Honig Saybrook Graduate School and Research Center
Colored light has been used as a treatment modality for physical and psychological conditions. A few studies have shown effects on cognitive processing, autonomic, and endocrine response as well as emotional and subjective experience. Responses follow a pattern of increased arousal with lower wavelengths (red vs. blue). Heart-rate variability provides a measure of parasympathetic and sympathetic autonomic nervous system function and has been used to measure mental stress, hypnosis, and emotional states and to study conditions including anxiety disorders, depression, anorexia, alcoholism, and PTSD. The purpose of this study was to examine the effects of red and blue colored light on the autonomic nervous system and on state anxiety. In addition, the relationship between response to color and the quality of absorption was examined. Twenty male and female adults were exposed to 10 minutes of red and 10 minutes of blue light through the eyes. The participants were divided into 2 equal groups with the order of administration counterbalanced. The sessions consisted of 5 minutes of no color exposure before and after each of the 10 minute color exposure periods. Heart-rate variability, finger temperature, and respiration were measured. Anxiety was measured at
iii baseline and after each color exposure using the short form of the Spielberger’s StateTrait Anxiety Inventory (Marteau & Bekker, 1992). The Tellegen Absorption Scale (Tellegen & Atkinson, 1974) was administered before the first 5-minute period. Data were analyzed using repeated measures analysis of variance and Mann-Whitney Tests to compare differences between the colors red and blue. Spearman Rank Order Correlations were used to test for linear relationships between psychophysiological response and anxiety and absorption. Although results did not support the hypothesis that there would a difference in psychophysiological response between exposure to red or blue light, the small sample size and large variance among the observed measures are factors. Results indicated correlations between anxiety and psychophysiological response and significant increases in anxiety following exposure to red and significant decreases in anxiety following exposure to blue. It is suggested that future studies investigate the effects of a multisession clinical intervention with a patient population.
iv Acknowledgments The author would like to acknowledge Thought Technology, Ltd., in Montreal, Canada for the loan of the ProComp equipment and the CardioPro software. I would like to acknowledge Robert Crago, Ph.D., of Neurobehavioral Health Services in Tucson, Arizona for the donation of the office space which was used to conduct the data collection.
v Table of Contents List of Tables ................................................................................................................... viii CHAPTER 1: INTRODUCTION ........................................................................................1 Background ..........................................................................................................................1 Purpose and Rationale..........................................................................................................2 Research Questions ..............................................................................................................3 CHAPTER 2: REVIEW OF THE LITERATURE .............................................................5 Colored Light .......................................................................................................................5 Physiology................................................................................................................5 Retinohypothalamic Tract ............................................................................5 Nonvisual Receptors ....................................................................................5 The Hypothalamus .......................................................................................7 The Pituitary Gland ......................................................................................8 The Pineal Gland..........................................................................................9 Possible Extrocular Mechanisms .................................................................9 Review of Research with Colored Light ................................................................13 Clinical Approaches ...............................................................................................23 Seasonal Affective Disorder ..................................................................................29 Nonocular Clinical Applications of Color .............................................................33 Discussion ..............................................................................................................39 Heart Rate Variability (HRV) ............................................................................................37 History....................................................................................................................37 Physiology..............................................................................................................38 Mathematical Analysis...........................................................................................39 Theoretical and Methodological Considerations ...................................................41 Research on Psychological Conditions ..................................................................43 Mental Stress ..............................................................................................43 Hypnosis ....................................................................................................44 Emotional State ..........................................................................................45 Anxiety.......................................................................................................47 Panic Disorder ............................................................................................49 Panic Disorder and Depression ..................................................................51 Depression..................................................................................................54 Depression and Coronary Artery Disease ..................................................55 Anorexia Nervosa ......................................................................................55 Post-traumatic Stress Disorder (PTSD) .....................................................56 Alcoholism .................................................................................................57 Discussion ..................................................................................................59 Conclusion .............................................................................................................55 CHAPTER 3: METHOD ...................................................................................................61 Participants .........................................................................................................................61 Design ................................................................................................................................61
vi Measurement ......................................................................................................................62 Psychophysiological Data ......................................................................................62 Absorption..............................................................................................................63 State Anxiety..........................................................................................................64 Color Preference ....................................................................................................64 Procedure ...........................................................................................................................65 Variables ............................................................................................................................66 Research Questions ............................................................................................................66 Data Analysis .....................................................................................................................67 CHAPTER 4: RESULTS ...................................................................................................68 Research Question One ......................................................................................................70 Research Question Two .....................................................................................................75 Research Question Three ...................................................................................................77 Research Question Four .....................................................................................................79 Additional Findings ...........................................................................................................80 CHAPTER 5: DISCUSSION.............................................................................................82 Summary of Results ...........................................................................................................82 Delimitations ......................................................................................................................83 Limitations .........................................................................................................................83 Design Considerations and Future Research .....................................................................85 CHAPTER 6: CONCLUSION ..........................................................................................91 REFERENCES ..................................................................................................................93
APPENDIXES Appendix A Consent to Participate in Research ..............................................................104 Appendix B General Information Form ...........................................................................109 Appendix C Recruitment Flyer ........................................................................................110 Appendix D Short Form of the Spileberger State-Trait Anxiety Scale ...........................111 Appendix E Tellegen Absorption Scale...........................................................................112
vii List of Tables Table 1: Shealy et al. (1996) Findings ...............................................................................14 Table 2: Selected Frequency Domain Measures of HRV ..................................................40 Table 3: Basic Counterbalanced Design ............................................................................62 Table 4: Definition of Dependent Variables ......................................................................63 Table 5: Frequency Counts for Selected Variables (N = 20) .............................................69 Table 6: Descriptive Statistics for All Outcome Measures Including Significance Testing. Repeated Measures ANOVA with Bonferroni Adjusted Pairwise Comparisons ....................................................................................................70 Table 7: Differences in Outcome Measures during Viewing Red or Blue Light. Wilcoxon Matched Pairs Tests ........................................................................73 Table 8: Differences in Outcome Measures for Average Color Response with Average Baseline Response Wilcoxon Matched Pairs Tests ...........................74 Table 9: Spearman Rank-Ordered Correlations for Psychophysiological Responses with Absorption and Other Demographic Variables .......................................76 Table 10: Spearman Rank-Ordered Correlations for Psychophysiological Responses with Anxiety Measures ....................................................................................78 Table 11: Spearman Rank-Ordered Correlations Between Pretest Anxiety Score and Pretest Psychophysiological Measures ............................................................80 Table 12: Comparison of Anxiety Measures Based on Presentation Order of Color Stimuli. Mann-Whitney Tests ..........................................................................81
1 CHAPTER 1 INTRODUCTION Background There is little doubt that color greatly affects our subjective experience and there are significant cultural associations to color. Color is a large component of conscious experience as well as eliciting unconscious instinctual responses. Research has shown effects of color on mood, physiology, and health (Aaronson, 1971; Gerard, 1958; Gottlieb & Wallace, 2001; Nowak, 1981). The purpose of this study is to examine the effects of red and blue colored light on the autonomic nervous system. In addition to measuring physiological arousal, state anxiety will be measured with a brief questionnaire. Unfortunately, research has been limited by many factors and more recent measurement techniques, such as heart rate variability, are available that provide information with greater specificity and clarity (Bernston et al, 1997; Porges, 1995; Task Force, 1996). Clinically, colored light has been used as a therapeutic modality for a range of conditions, including seasonal affective disorder (SAD; Brainard, 1998; Oren et al., 1991; Stewart, Gaddy, Byrne, & Miller, 1991) and those of a psychotherapeutic nature (Breiling, Nelson, & Hartley, 1997; Liberman, 1991). Aside from anecdotal reports, there is a lack of scientific validation of the efficacy of these clinical approaches. Can color be used as medicine? To determine whether colored light is clinically effective, first the effect of color on physiology must be observed. The mechanism of action for the physiological effect of color on the autonomic nervous system via the retinohypothalamic tract has been mapped out (Asuhide, Iyamoto, Ziz, & Ancar, 1998).
2 In this dissertation, I observe the response to two colors of light on physiology and anxiety. I also examine whether the trait of absorption is related to level of response to color. I use heart rate variability (HRV) as the primary measure of the effects of color on the autonomic nervous system. HRV measures have been correlated with health outcomes. HRV data provide specific values which correlate with parasympathetic and sympathetic nervous system (Bernston et al., 1997; Porges, 1995; Task Force, 1996). An inverse pattern of arousal and wavelength has been observed with colors on red side of the spectrum being more activating than colors on the blue-violet side of the visible spectrum. This has been termed the warm-cool hypothesis (Aaronson, 1971), which refers to the subjective impression of lower wavelengths being considered to be warm (red-orange-yellow) and longer wavelengths (blue-violet) are considered to be cool. Purpose and Rationale As this dissertation compares psychophysiological and emotional (i.e., anxiety) responses to two different colors on opposite sides of the visual spectrum, this study does not simply address the general question of whether colored light affects physiology. Because of the choice to use red and blue, the purpose is more specifically to investigate differences in autonomic arousal. Very few studies have been published that obtained physiological data on response to colored light. This dissertation also includes a measurement of absorption (Telegen & Atkinson, 1974). Measuring this trait may provide information as to whether a personality trait or characteristic related to responsiveness to stimulus and alterations of
3 consciousness is associated with magnitude of physiological effect of the colored light intervention. Much of what has been reported clinically has been anecdotal in nature. There is a need for more systematic research to further these interventions as an integrative medicine technique. Another benefit justifies the expenditure of effort and resources required. Although this study did not measure a clinical course of treatment, a finding of a significant response to a short exposure to colored light could indicate that longer and more frequent exposure may have clinical utility. This dissertation contributes to understanding of a controversial topic surrounding two different kinds of patterns seen with exposure to color. Research based on the warmcool hypothesis and sympathetic/parasympathetic response often describes a universal response to color. This relates to parasympathetic and sympathetic autonomic balance. Alternatively, clinicians have worked with individual response. Colors are related to psychological issues. Emotional reactions or abreactions in response to color also vary in the same way. This highly variable response pattern was observed in therapeutic clinical settings (Liberman, 1991). In the literature review, I compare and contrast these two approaches, which are based on a universal pattern related to arousal, and approaches that focus on individual variability of response. I review research that investigates physiological and psychological responses to colored light. This also has implications for the development of models using color for therapeutic purposes. Research Questions The following research questions are addressed in this dissertation:
4 Is there a significant difference in the autonomic nervous system measures when participants view red compared to blue light? If so, what are the characteristics of this pattern? Is there a linear relationship between absorption and psychophysiological response? Is there a linear relationship between anxiety and psychophysiological responses? Additionally, is there a linear relationship between anxiety and baseline psychophysiological response?
5 CHAPTER 2 REVIEW OF THE LITERATURE This literature review focuses on two main areas: colored light and heart rate variability (HRV). The review of the literature on color contains three main components: what is known about human physiology as related to the response to light, a critical review of prior research, and a description of clinical approaches. I will provide a historical context of the use of HRV and some of the theoretical issues, define HRV and its components, and review the literature on its use for a variety of states and conditions. Colored Light Physiology Retinohypothalamic tract. The retinohypothalamic tract (RHT) is the primary pathway for nonvisual effects of light on the limbic and endocrine systems. The circadian or 24-hour rhythm exists for every homeostatic function of the body, such as the sleepwake cycle and body temperature (Kandel & Schwartz, 1985). The circadian rhythm is controlled by the mammalian clock, which is located in the suprachiasmatic nucleus (SCN) of the hypothalamus (Ramamchandran, 2002). This clock is entrained by the daily light/dark cycle. By the function of the hypothalamus and pituitary glands, light has an effect on the endocrine system. From the action of melatonin and other consequent results of endocrine functioning, an organism’s exposure to light through the eyes has a broad range of significant effects on functioning of the major systems and physiological processes of the body. Nonvisual receptors. Two kinds of receptors in the retina, rods and cones, are responsible for the detection of light and visual information. These receptors contain
6 visual pigments, rhodopsin and cone opsin respectively, which undergo a chemical reaction and transformation that in turn excite retinal ganglion cells to carry this information through the cortical visual pathways to the occipital lobe (Kandel & Schwartz, 1985). A third kind of receptor transmits nonvisual information about intensity and wavelength of light to entrain the circadian clock of the SCN. This third receptor operates independently and in the absence of rods and cones. Evidence for this includes the fact that both blind persons with no conscious perception of light and mice that have had all rods and most cones destroyed continue to exhibit normal entrainment of the circadian rhythm (Asuhide et al., 1998; Freedman et al., 1999; Lucas, Freedman, Munoz, Garcia-Fernandez, & Foster, 1999). The nonvisual photoreceptor operates via a different photopigment than the one found in the visual receptors. Photopigments are defined as “organic molecules that absorb light energy and initiate photobiological processes” (Brainard, 1998, p. 12). Two different types of photopigments have been implicated (Asuhide et al., 1998). Asuhide et al. (1998) provided evidence for their conclusion that two types of vitamin B (flavin) based photoactive molecules called cryptochromes are responsible for the circadian clock. Cryptochromes are also implicated as important in the circadian process as, in addition to the retina, they are also found in the circadian oscillator of the SCN (Barinaga, 1998). Melanopsin, an opsin-based photopigment is considered to be important but not crucial to circadian entrainment. Mice with an absence of melanopsin display severely attenuated phase resetting in responses to brief pulses of monochromatic light (Panda et al., 2002). There was a 40% reduction of response to light pulses (Ruby et al., 2002).
7 In addition to operating via a different photopigment, another difference between the nonvisual receptors and rods and cones involves their electrophysiological characteristics. The retinal ganglion cells projecting to the SCN of the hypothalamus fire in a transient fashion. These responses are dependent on the intensity of the light stimulus. Other retinal ganglion cells projecting to the optic nerve and not the SCN fire with a robust train of action potentials (Warren, Allen, Brown, & Robinson, 2003). The hypothalamus. The retinohypothalamic tract is one of the ways that the hypothalamus connects the nervous system to the ANS and the endocrine system. Information from the photoreceptors in the retina is transmitted to the SCN of the hypothalamus, which contains the mammalian clock (Ramachandran, 2002). The process of gene transcription is the mechanism by which the mammalian clock exercises its control on hypothalamic function. Gene transcription is the first step in the process of gene expression. An RNA copy is made from a DNA gene sequence and the gene is switched on (Holzberg & Albrecht, 2003). The hypothalamus can be considered to be the instrument or control panel of the brain. The hypothalamus has an important role in maintaining homeostasis and integrating responses of the ANS (Ramachandran, 2002). The hypothalamus is a coordinating center that integrates various inputs to ensure a well-organized, coherent, and appropriate set of autonomic and somatic responses (Kandel & Schwartz, 1985). The hypothalamus controls the endocrine system. It regulates thirst, hunger, body temperature, water balance, and blood pressure (Ramachandran, 2002). The gland secretes neurotransmitters, neuromodulators, and neurohormones (Farr, 2002; Ramachandran, 2002). The hypothalamus plays a role in emotional function, as it shares the mammillary bodies with
8 the limbic system. Learning and memory are affected by the hypothalamus with the release of adrenocorticotropin and vasopressive analogues. These hormones are assumed to contribute to these cognitive functions either directly or by mediating arousal (Kandel & Schwartz, 1985). The pituitary gland. The pituitary gland is controlled by the secretory action of the hypothalamus through its rich neural and vascular connections. The pituitary gland releases a variety of hormones that control functions such as growth, thyroid function, sexual and reproductive functioning, water concentration of bodily fluids, and blood pressure. The pituitary gland controls the production of adrenal hormones, including cortisol (Kandel & Schwartz, 1985). Cortisol is one of the hormones that under normal conditions varies with a 24hour rhythm. Partly from their control of cortisol levels, the hypothalamus and the pituitary are involved in sympathetic activation of the ANS. This stress response is also referred to as the fight-or-flight response. This response mobilizes the organism for selfpreservation. During the stress response, internal needs are subjugated in response to external demands (Porges, 1995). Levels of cortisol and corticosteriods rise during this sympathetic activation. This response is necessary in acute situations of danger or threat. A dysfunctional pattern of long-term, chronic, sympathetic activation negatively affects immune functioning, partly from the effect of immunosuppressive effects of cortisol (Porges, 1995). The pineal gland. The major hormone secreted by the pineal gland is melatonin. From the action of melatonin, the pineal gland is responsible for the sleep-wake cycle of the circadian rhythm. The pineal gland does not store melatonin. Melatonin is secreted as
9 needed by simple diffusion into the blood and cerebral spinal fluid. The pineal gland does contain other hormones and proteins including immunoreactive arginine vasotocin (AVT) that also have a regulatory effect on sleep and arousal. The pathway from the hypothalamus to the pineal gland is through the brainstem (the medial forebrain bundle) and the superior cervical ganglia of the spinal cord. The pineal gland also receives innervation from the sympathetic nervous system (Ehrlich & Apuzzo, 1985). Melatonin production is entrained by light and is regulated by the SCN. Melatonin is produced in the pineal gland from serotonin in two enzymatic steps (Ramamchandran, 2002). Melatonin production is confined to hours of darkness and is sensitive to inhibition by light. Melatonin levels follow a diurnal cycle and nighttime levels are 10 times higher than daytime levels, exerting an influence on the circadian rhythm (Erhlich & Apuzzo, 1985). Lucas et al. (1999) described melatonin as acting as an internal representation of nighttime. In addition to its effect on the sleep-wake cycle, melatonin is responsible for a wide variety of physiological actions exerting both endocrine and nonendocrine effects. Melatonin acts on the adrenal, thyroid, pituitary and pineal glands. Behavioral effects include an influence on aggression and passive avoidance, and it is believed that melatonin reduces locomotor activity. In the nervous system, serotonin and GABA levels are altered by melatonin, as is brain electrical activity as measured by electroencephalogram (EEG). One possibility is that reductions in locomotor activity and the inhibitory effects of GABA are necessary for sleep onset and maintenance. Melatonin is also produced in the SCN of the hypothalamus, in the retina, and in the intestine.
10 Melanin production in the skin responds to sunlight exposure and also relates to the action of melatonin (Erlich & Apuzzo, 1985). Arginine vasotocin is a peptide with similar effects to melatonin and it is more potent. It has sleep-inducing and anticonvulsant effects via a serotonergic pathway and it activates a descending GABA (an inhibitory neurotransmitter) pathway (Erlich & Appuzzo, 1985). Possible extrocular mechanisms. The physiological effect of light through the eyes appears to be a well-defined mechanism. Although this process may sufficiently explain the autonomic and endocrine responses that have been observed, other mechanisms for light’s action have been proposed. These involve the effect directly on the cells or tissues or explanations related to the effect of light on the electromagnetic field. Wade, Taylor, and Siekevitz (1998) proposed that the intensity of light equal to sunlight that penetrates the head and reaches cortical tissue exerts an effect on neurophysiology. The researchers studied slices of rat cerebral cortical tissue. When this brain tissue was exposed to low levels of visible light, the same intensity as sunlight, there was an enhanced release of neurotransmitter GABA. GABA helps neutralize the effects of glutamate. Glutamate has been described as a brain chemical that produces excitement. An increase in GABA reduces racing thoughts associated with anxiety. In humans, a decrease in GABA leads to an increase in anxiety (Lydiard, 2003) When higher light intensity was used, the release of GABA was suppressed. This may occur due to direct polarization of the cell membrane in either neural or glial cells. Although the
11 exact mechanism for these effects is not known, it is known that photoreceptive molecules and processes do exist in surface brain tissue (Wade et al., 1998). Gottlieb and Wallace (2001) reviewed the history of phototherapy including the theoretical aspect of optometic phototherapy or syntonics. From their review, they hypothesized that blood irradiation may be a mechanism by which light has a physiological effect on us. This irradiation may operate through exposure of the blood vessels of the retina to light. Light exerts an effect on hemoglobin and bilirubin through the skin. Specific wavelengths of light alter heme oxygenases. This results in changes in vasodilation, neurotransmission, and gene expression and has antioxygenation, anti-inflammatory, and antiviral properties. Laser light exposure on the skin causes hemoglobin to release free nitric oxide, which relaxes blood vessels. Exposure to blue light reduces bilirubin levels; this is the mechanism for treatment of jaundice in infants (Salih, 2001). Another possibility to consider for the mechanisms of the influence of color is the electromagnetic field surrounding the physical body. Colors are prescribed as part of ayurvedic medicine and are attributed different health properties. According to Lad (1984), chakras are defined as “energy centers in the body that are responsible for the different levels of consciousness” (p. 165). They correspond physiologically to the nerve plexus centers and to the glands of the endocrine system. There is a correlation with the colors of the spectrum and the chakras; the base chakra at the root of the spine corresponds to red, and the crown chakra responds to violet (Judith, 1996). In a study that used self-report of experience in relation to areas of the body corresponding to the chakras, Kent-Ulman (1984) observed a pattern of color response.
12 Red was more often reported when individuals focused on the lower regions of the body; yellow and green at the mid-region; and blue, white, and silver in the upper regions. This pattern was not statistically analyzed. Judith (1996) discussed the ways in which chakras and their associated colors have been related to psychological constructs and form the basis for a psychospiritual development system. For example, the base of the spine, associated with red, is related to life force. The solar plexus, associated with yellow, is related to personal power. The crown of the head, associated with violet, is related to spirituality. Another system of associating colors with psychological or spiritual qualities is based on Buddhist philosophy. The five wisdom energies or Buddha families are each associated with a different color. These translate as clarity-blue, enrichment-yellow, passion-red, activity-green, and spaciousness-white. In the Maitri Space Awareness Program, there are five rooms that each contain one of these colors in the floor, walls, ceiling, and windows. Participants in the program spend a series of daily sessions practicing open-eyed meditations in each of these rooms with the purpose of intensifying psychological responses and patterns and facilitating personal growth (Rockwell, 2002). Gerber (2001) discussed color as a vibrational medicine technique and stated that “colors of light in the visible spectrum are lower octaves of higher vibrational energies that contribute to the auric field and subtle bodies” (p. 275). Gerber derived his explanations from an energetic and spiritual paradigm without providing reference to scientifically accepted evidence. Gerber’s and these other explanations have not been empirically validated.
13 Review of Research with Colored Light Both physiological and subjective psychological effects of colored light have been studied. Physiological indices such as neurotransmitters and hormones, and psychophysiological measures of arousal including muscle tension, blood pressure, galvanic skin response, HRV, and alpha brainwaves have been measured. Some studies examined mood and emotional associations and psychological states such as depression and introversion in relation to color. The following section reviews these studies. Shealy et al. (1996) conducted a small pilot study that measured changes in a variety of neurochemicals and neurohormones in response to colored light (see Table 1). Five healthy adults were exposed to 20 minutes each of red, green, and violet light, which flickered at a rate of 7.8 Hz. This rate was intended to entrain brain waves in the alpha range, thus inducing relaxation. Each exposure was separated by at least two days. Blood samples were taken before and 10 minutes after the light exposure. The greatest number of increases and decreases in blood levels were seen with green light. The greatest changes were seen in levels of oxytocin.
14 Table 1 Shealy et al. (1996) Findings Neurochemical Oxytocin
Color Red Green Violet
Norepinephrine
Green Violet
Serotonin
Red Green Violet
Beta endorphin
Red Green Violet
Growth hormone
Red Green Violet
Result: % Change from Basline 3 participants: +50%, +67%, +138% 4 participants: +26%, +36%, +56%, +64% 3 participants: +56%, +88%, +157% 2 participants: -25%, -33% 1 participant: -33% 2 participants: +25%, +127%, 2 participants: +76%, +132% 1 participant: +63% 1 participant: +60 2 participants: +32%, +34% 1 participant: +70% 2 participants: +100%, +167% 3 participants: +50%, +100%, +300% 2 participants: +50%, +100%
Neurochemicals have been shown to deviate normally by less than 20% within 30 minutes under stable conditions. Shealy did not provide information about the parameters of these measurements. To judge the clinical utility of these results, it is necessary to know the range of normal values. The usefulness of these changes would depend on individual health status including initial values. In spite of the lack of information, the study does provide a demonstrable effect of short light administration.
15 Although the small sample size and lack of statistical analyses greatly limit the usefulness of these results, the information obtained encourages further investigation. Gerard (1958) examined the effects of exposure to red, blue, and white light. Twenty-four male participants were exposed to red, blue, and white light with each condition preceded by an 8-12 minute resting period in dim white illumination. Order of exposure was counterbalanced to control for sequence and order effects. Autonomic measures included blood pressure, palmar conductance level, respiration rate, heart rate, and eye-blink frequency. Electroencephalogram (EEG) was used to measure alpha percentage and alpha amplitude occipitally. Anxiety was measured using the Taylor Manifest Anxiety Scale (Taylor, 1953, as cited in Gerard, 1958). Subjective rankings of a list of affect descriptions (e.g., friendly-kind, warm-hot) related to each color as well as rankings on 4-point scales of relaxation versus tension and soothing versus irritating were also gathered. Results indicated significantly greater autonomic and cortical arousal for red light as compared to blue light. This was true for all of the physiological measures except for heart rate. Gerard did not provide any ideas as to why heart rate changes did not reach significance. These results were based on mean changes from resting level for each of the color conditions. Significantly greater well-being and relaxation were reported during the blue condition and more tension and arousal were reported during the red condition. Results for the anxiety scores indicated that participants with greater anxiety had greater disturbance in response to red as well as more relief in response to blue. This finding has implications for clinical use of color. Given these results, it could be hypothesized that there is a positive correlation between severity of dysfunction and strength of the clinical
16 response to color. Further research with patients with psychiatric illness is necessary to investigate this hypothesis and investigate the usefulness of color as a clinical treatment. Research with healthy individuals could be used to determine the value of color exposure for peak performance or promoting optimal functioning (Gerard, 1958). This study is an excellent contribution to knowledge of human response to colored light. A broad range of psychophysiological variables were measured and their correlation with each other was examined. This study examined the role of both color preference and affective responses in relation to the psychophysiological response. Wilson (1966) investigated psychophysiological response to two colors. Twenty participants were exposed to alternations of 5 red and 5 green colored slides for one minute each. The participants sat in front of a 2-foot square, translucent screen placed four inches away. Half of the participants viewed green first and the other half viewed red first. Galvanic skin response (GSR) and conductance levels were measured at 10-second intervals during the color presentation. Results were significant for differences in both of these measures for red and green, indicating significantly greater arousal during red light exposure. Although Gerard (1958) used different colors in his study, the results of Wilson’s (1966) study was similar in that lower wavelengths (the red end of the spectrum) were also correlated with greater arousal. A major criticism of this study is that color exposure was for only one minute. Lehrl, Gerstmeyer, Jaco, Frieling, and Henkel (2007) measured alertness and cognitive function in response to yellow, blue and white light. Forty-four participants were asked to rate their level of alertness and to complete on a 7-point scale and complete a cognitive task following exposure to 20 seconds each of the following conditions: room
17 light, yellow light, blue light, and white light. The color conditions were separated by two minutes. The cognitive consisted of the reading of a line of 25 letters projected onto a screen. The speed at which the letters were read was timed individually. The authors considered speed of processing on this task to be related to level of fluid intelligence and directly connected with IQ. Results indicated both subjective judgment of alertness and speed of processing to be significantly greater after blue light compared to yellow light. It is interesting to note that the color exposure was only 20 seconds. Future studies could examine longer exposure times. The authors made an interesting point in their discussion that because of the short length of the exposure, the effects are not likely to be the results of changes in melatonin that has been shown to vary in many minutes or hours. They proposed that dopamine or norepinephrine may be responsible for their results. McManemin (2005) measured heart rate, HRV, and galvanic skin response in 23 adults in response to two different colors using the Photron Light Stimulator. Redorange and indigo were administered consecutively for five minutes each. There was a 5minute prestimulation baseline and a 5-minute poststimulation baseline. The light flickered at a rate of 14 cycles per second. There was a significant increase in galvanic skin response from prebaseline to red-orange, indicating autonomic activation. There was a significant reduction in heart rate during the indigo administration and further reduction during the baseline period. There were significant changes in the low frequency of the HRV, indicating increased balance of the sympathetic and parasympathetic branches of the ANS. These were from pre- to postbaseline, red-orange to postbaseline, and indigo to postbaseline. McManemin reported that the contribution of indigo was the greatest in these changes. Additionally, significant changes were seen in low frequency to high
18 frequency ratios: from pre- to postbaseline and indigo to postbaseline. Changes in this parameter of HRV were also noted to indicate increased balance of the ANS and are associated with improvements in psychological and physiological functioning. Two criticisms of this study are that there was no resting period between the two colors and that there was no counterbalancing of the order of administration. The changes seen with indigo were not independent of the prior administration of red-orange. McManemin cautioned that this study was preliminary and that she planned to replicate this with more participants. Clinical work with one patient revealed some noteworthy changes in psychological and cognitive functioning (McManemin, 1995). A patient between 20 and 25 years old, who suffered a severe traumatic brain injury approximately 10 years earlier, underwent a series of treatments with strobic colored light (using the Lumatron Light Stimulator). This intervention utilizes photic driving along with the colored light. Flashing light has been shown to entrain brainwaves, increase visual imagery, and facilitate the induction of an altered state of consciousness (Dieter & Weinstein, 1995; Glickson, 1986-1987). The treatment consisted of 40 sessions of 30 minutes in duration over an 8-week period. During these sessions, the patient looked at three different colors for 10 minutes each. During the course of the 40 sessions, the patient looked at combinations of 11 different colors (ruby, red, red-orange, orange, yellow, yellow-green, green, blue-green, blue, indigo and violent). The choice of the three colors varied with each session. The colored light flashed at 12 cycles per second. This is in the sensory motor range (SMR) and is considered to entrain a state of relaxed alertness. During each session of exposure to the light, the patient was instructed to continue talking in a manner
19 similar to free association. The therapist sat near the patient and did not question or otherwise engage in conversation with the patient, except to encourage the patient to continue talking through the entire session. The Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Wechsler Adult Intelligence Scale-Revised (WAIS-R), the Wechsler Memory Scale (WMS) and the Wisconsin Card Sorting Test (WCST) were administered before and after the course of treatments. Improvement was found in all four of the measures after the 8-week course of treatment. On the MMPI-2, results indicated a reduction of depression, reduced focus on somatic problems, and reduced anxiety. On the WAIS-R, there was statistically significant improvement on the arithmetic subtest. This was interpreted as an improvement in discursive reasoning, that is, the ability to hold problems in one’s mind while solving them. There was a trend in the positive direction in the following subscales: picture arrangement, information, comprehension, and similarities. These results indicated slight improvement in visual organization, nonvisual problem solving, judgment and insight, and verbal concept formation. Improvement on the information subtest indicates increased ability to access previously encoded information. On the WMS, there was improvement in intermediate memory and there were eight intrusive errors on the pretest and none on the post-test. There was some improvement on the WCST indicating improvement in frontal lobe executive functioning, as he was able to develop a working strategy to arrive at correct underlying rules on the post-test. It is not possible to sort out the possible effects of improved alertness and attention that may be a result of the treatment. The improvements in cognitive performance may be due to this. Irregardless, these results warrant further investigation to determine any clinical utility for the treatment.
20 Aaronson (1971) examined emotional associations to color in three individuals and used hypnotic suggestion as opposed to exposure to colored environments or colored light. The three participants were each given the suggestion under a hypnotic state that they would see everything in shades of a specific color for two hours after the induction. This procedure was repeated for 11 different colors including white. Three control sessions were interspersed among the sessions. A fourth participant could not be hypnotized and functioned as a simulator, that is, he was given the same instructions as the participants who were hypnotized although he was not considered to have entered into a hypnotic state of consciousness. The order of administration varied among the participants, though the specific color order was not reported. Some of the responses following the hypnotic period were as follows: red was associated with feeling happy, orange evoked associations of vegetation, yellow-green was stimulating, and green evoked feelings of calm happiness. Participants became serene and relaxed during the blue-green period, blue evoked a sense of calm and relaxation, and purple seemed rich and full and evoked a mystical experience. This study has limited scientific value due to the small sample size, and the lack of standardization or any statistical analysis of the response. The results are congruent with other findings indicating greater arousal with lower wavelengths. It is interesting to note that the simple suggestion of color elicited responses congruent with some of the results of studies using actual exposure to color, this perhaps being an example of a conditioned response. Visual imagery or rehearsal of an action has been shown to be correlated with concurrent physiological and neurological patterns of activation in the motor cortex (Hale, 1982; Sparing, 2002), and generation of mental images involving color activate similar cortical
21 regions as perception of color (Howard et al., 1998). It is possible that visualization of color will have similar psychophysiological and emotional responses to actual exposure to colored light. These findings suggest that the use of color meditations, which involve a process of inner reflection with eyes closed while thinking about or visualizing a specific color, may be a useful therapeutic technique. It would be useful to expand this study to include measurement of psychophysiological response such as galvanic skin response or distal temperature to the hypnotic suggestion. Dearing (1996) studied the relationship of personality and depression to color preference in response to colored light. Sixty male and female participants were rated on depression and introversion/extroversion using the Beck Depression Scale and the Kiersey Temperament Sorter. The participants were divided into four groups: nondepressed introvert, depressed introvert, nondepressed extrovert, and depressed extrovert. The depressed participants varied from mild to moderate on the Beck Depression Inventory. The participants were each shown a series of 11 different colors for two minutes each. They were asked a series of questions about their reaction to the light. Following each color exposure the participants were asked to rate their preference for the color on a scale of 1 to 10. Results for the depressed/nondepressed group showed a significant difference for one color, with the depressed group having a lower preference for ruby. There was a nonsignificant trend with higher preference for all colors in the nondepressed group. For the temperament groups, results showed a significant preference for three colors, with the extravert group having a higher preference for yellow, yellow/green, and green. The greatest difference in preference between the introvert and extravert groups
22 was for the color yellow. Analysis of the interaction of depression and temperament revealed significant difference for two colors: red/orange and blue. The extrovert/nondepressed group had a higher preference for red/orange compared with the extrovert/depressed group. For the nondepressed group, the extravert subgroup had a significantly greater preference for blue as compared to the introvert subgroup. The nondepressed introverts had a lower preference for blue than all of the other groups. Dearing (1996) made some conclusions about the meaning of these results based on a model developed by Vazquez (1996) in which each color is assigned psychological attributes. This model was developed by observing psychotherapy patients while they engaged in free association while observing the colored light. Although the model has never been validated, Vazquez made some interesting observations. For example, in this model, red/orange is associated with issues of conscience, spontaneity, creativity, and interpersonal boundaries. Dearing (1996) proposed that extroverts may find it more difficult to handle the state of depression because it inhibits their ability to enjoy the outer world. Dearing theorized that extroverts may prefer red/orange because of their tendency to be outgoing and have better interpersonal boundaries. This study was limited by several factors including sample size and a lack of control for use of antidepressant medication and demographics of the participants. Results of this study suggest that color preference is related to at least one personality trait and a psychological condition. Inferences about reasons for these differences would be supported if more information were known about the correlations between psychological factors and color preference. Examination of the relationship of color preference to psychophysiological measures is warranted. It would also be useful to
23 determine whether the level of physiological arousal differed according to color preference. Clinical Approaches The use of color for healing predates the modern era. Evidence exists for the use of color across cultures since the beginning of recorded history. A comprehensive review of this history is beyond the scope of this essay. There are many useful sources for this information (Birren, 1997; Bloch, 1990; Clark, 1975). Psychotherapeutic and neurological uses of colored light have their inception in syntonics, a subspecialty of optometry. Syntonic optometry is the branch of ocular science that deals with the application of selected visible frequencies through the eyes (College of Syntonic Optometry, 2001). Spitler (1941, as cited in Liberman, 1991) defined syntony with the following: A condition of syntony exists in a stable, integrated personality and results from a state of equilibrium in the autonomic nervous system. Syntony is affected by the color of light entering a person’s eyes. Hence, a maladjusted individual may be syntonized and restored to health by stimulating the eyes with filtered light of appropriate color. (p. 76) Spitler, in The Syntonic Principle (as cited in Liberman, 1991) provided historical incidents, clinical records, and personal testimony and concludes that variations in the wavelength of light entering the eyes affects the rate of cell growth, physical development, reproduction, endocrine balance, and the improvement in a broad range of cognitive, physical, and behavioral symptoms. In addition, there is full expansion of constricted visual fields. Although there is usually spontaneous recovery of function over time in mild traumatic brain injury, syntonic treatment is reported to accelerate recovery.
24 Both Downing (1996) and Vazquez (1996) employed the Lumatron Light Stimulator or the equivalent portable device, the Photron Light Stimulator, in their therapeutic approaches. This device has also been used in several research studies. This device was developed by John Downing, O.D., Ph.D. Both the Photron and the Lumatron have a white light source using a full spectrum plasma gas light source (xenon gas bulb). Color purity is supplied by 11 color filters of optical quality glass. Downing (1996) reported that these filters produce pure and precise wavebands of colored light held to a strict tolerance of accuracy. The strobe rate adjusts from one to 60 cycles per second. The therapist or researcher controls the strobe rate of the light and the color. The purpose of the strobe is to entrain brainwaves (photic driving) to a specific frequency (i.e., in the alpha or theta range). Other physiological effects of photic driving have also been found (Diehl, Stodiek, Diehl, & Ringelstein, 1998). The brightness of the light is low; the light projected by the Photron and the Lumatron vary from approximately .151 lux to 31.101 lux. As a comparison, the full spectrum light used to treat seasonal affective disorder is usually more than 2,500 lux. The color filters used are calibrated to include the entire spectrum of visible light, except ultraviolet. The following colors are included: ruby, red, red-orange, yellow, yellow-green, green, blue-green, blue, indigo, violet, and white. Downing’s (1996) therapeutic approach used a checklist of symptoms to determine the autonomic balance of an individual. Downing characterized patients as either a fast-slow neurological type, which he believed loosely corresponds to sympathetic dominance or parasympathetic dominance. Patients view colors on the blue (for fast neurological types) or the red side of the spectrum (for slow neurological types.). Flash rates in the beta range (from 13 to 15 Hz) are used with yellow to red and flash rates in the alpha to delta range
25 (10 Hz to 1 Hz) are used with blue-green to violet. Although Downing’s system may be clinically effective, the difference in flash rate for each color precludes an analysis of the effects of color alone. Patients typically are exposed to the colored light for 20 sessions of 20 minutes each. Patients sit alone and view the colors silently. Downing measures functional visual fields before and after a series of treatments. He reports significant improvements (i.e., expansion) of the visual field as a result of the treatments. A functional visual field is defined as “the measure of the usable area that an individual can process fixating a central target, while a mobile or (kinetic) target is moved in from the periphery from invisible to visible” (Fast, Shayler, & Pharr, 2000, p. 5). Visual field testing can be done manually or with a various devices. A chart is created which reveals blind spots, and the pattern of the extent to which the periphery of the visual field is seen or not seen. Functional visual fields are a measurement of the “total sensory input, integration and output response of the individual to a visual stimulus” (Pesner, 1995, as cited in Heinrich, 2006, p. 10). They are considered to be a measure of physical and emotional health, with constricted visual fields correlated with neurological or physiological (e.g., brain injury, fatigue) or psychological (e.g., depression) dysfunction. In addition to visual field improvements, Downing (1996) reported that in his clinical work, he found changes in cortical functioning as measured by EEG and increases in muscle strength. He found decreases in cognitive and emotional symptoms as measured by patient self-report. Liberman’s (1991) and Vazquez’s (1996) clinical approaches differed from that of Downing (1996) in a fundamental way. The differing approaches are analogous to
26 allopathic versus homeopathic medicine. Downing applied the color that will relieve a symptom or effect a change directly, for example, using blue to slow a hyperactive patient. Both Liberman and Vazquez used colors that antagonize the symptom or intensify an emotional reaction or stimulate traumatic memories. This can be compared to the homeopathic principle of “like cures like” or the law of similars. A significant difference in the treatment approaches is that patients were encouraged to talk with the therapist while viewing the color. The goal of this approach is to use color to facilitate or increase the effectiveness of the psychotherapeutic process. Liberman (1991) described the development of his approach. Initially he used the principles of syntonics, which assigned universal uses for different colors. Liberman discovered that a specific color would have different or even opposite effects when used with different individuals. His goal was to uncover unconscious causes of disturbance, as opposed to a palliative approach, which eased the symptoms. He theorized that a palliative approach did not produce a lasting change. Lieberman used a color-preference technique that is subjective in nature. Patients were asked to choose their preference from pairs of colors (red/blue, yellow/violet, or lime/turquoise). Lieberman related his clinical observations. Colors preferred by clients or colors that elicited reports of comfort were palliative and produced positive emotions. Liberman chose to use colors that the patients did not prefer and during exposure, they reported feelings of discomfort. He reported that in his clinical experience these disturbing colors elicited past or present painful experiences. Liberman also related his therapeutic approach to the homeopathic principle, which he described as “the most appropriate remedy for a patient is one with a vibration that is equivalent to the patient’s pathology” (p. 187). Liberman planned his choice of
27 colors for each patient based on their level of comfort. He started with colors that produced a mild level of discomfort and proceeded to the colors that elicited higher levels of discomfort. Two case reports of psychotherapeutic processes are reported. Vazquez’s (1996) approach is based on a similar philosophy as Liberman. Vazquez attempted to create a structured assessment and scoring system to guide treatment, which he termed the photosensitivity assessment. This evaluative procedure utilizes both color preference as well as the patients self-report while exposed to the color stimulus. Patients are shown each of the 11 colors for 1 to 2 minutes. After being shown white, the colors progress in order along the spectrum from ruby to violet. The patient was asked five questions while viewing each color. The questions related to the patient’s reaction to the color, the appearance, somatic experience, thoughts, and emotions generated. The patients were asked to rate their preferences for each of the colors individually on a scale of 1 to 10 , with one indicating an aversion to the color and 10 indicating a strong preference for the color. Vazquez developed a scoring system for the responses to each color. The basic premise was to determine to which colors a patient responds with the most of what Vazquez termed distortions. These distortions are any visual images, anomalous colors, thoughts, somatic sensations, or emotions elicited by the color. In this system, the colors that elicit the most distortions trigger negative or suppressed emotions or traumatic or unhealed memories or conflicts. Visual responses are particularly interesting. For example, while viewing the light stimulus through a clear blue lens, the patient may report seeing many other colors besides blue or may report seeing movement or changing shadows. These responses are considered to be a projection from the client’s own psyche. Vazquez did not perform any analysis of the
28 reliability and validity of these responses. Vazquez created a model of inherent meanings or psychotherapeutic content and process related to each color (p. 74). He developed this model using empirical clinical observation over several years of thousands of patient responses during color-assisted psychotherapy sessions, as opposed to a predetermined theoretical model or system. Vazquez’s observations included both observing free association while looking at specific colors as well as observing responses during psychotherapeutic interventions concurrent the exposure to the light. This model warrants further investigation. Psychometric analysis of the photosensitivity assessment may determine that color preference and response provide a valid and clinically useful psychological and personality assessment. Vazquez’s (1996) clinical approach employed psychotherapeutic techniques such as those used with hypnosis or guided imagery. Two particular techniques were used. One can be described as flooding. For example, a patient is experiencing anger. The patient is directed to speak out loud: “I am angry or I am angry about _____.” The patient is asked to repeat the phrase while taking a breath in between each repetition. Vazquez reported that after 10 or 12 times, the emotion dissipates. Dysfunctional beliefs or thought patterns can also be addressed. Vazquez also developed a system of eye movements to be used while looking at the colored light (Vazquez & Breiling, 1997). No psychometric studies of Vazquez’s (1996) assessment methods have been done. Claims of therapeutic value have not been validated with more than anecdotal data or clinical observation (Vazquez, 1996; Vazquez & Breiling, 1997). Vazquez derived his method and model of color response by observing patients during treatment without controlled studies. Possibilities for future research include comparing color response and
29 preference to response on clinical assessments or personality scales. In addition, qualitative analysis of transcripts of free association responses to the colors would be very helpful to address the validity of this model. Determination of the clinical efficacy of Vazquez’s therapeutic use of color would require pre- and post-testing of psychiatric dysfunction on standardized and normed diagnostic scales of personality traits or psychiatric symptoms. Commonly used symptom checklists or structured interviews could also be used. These results could be compared with other forms of psychotherapy or pharmaceutical interventions. Psychophysiological measures can provide additional valuable information about the response during the assessment or during treatment. Seasonal Affective Disorder Seasonal affective disorder (SAD) is a subtype of recurrent mood disorder with a characteristic pattern of onset and remission (Wesson & Levitt, 1998). It is characterized as a depressive episode with an onset and remission related to season of the year. Occurrence is greater at higher latitudes during the winter in the northern hemisphere. Basically the disorder is caused by shorter days with reduced exposure to sunlight. The accepted treatment for SAD is a course of daily exposure to bright artificial light, which is usually full spectrum white light (Wesson & Levitt, 1998). In addition to the established literature and clinical practice conclusively demonstrating the effective treatment of SAD with full spectrum white light (Brainard, 1998) the clinical efficacy of exposure to colored light has also been investigated. The question addressed is whether specific monochromatic wavelengths yield more potent neurophysiological effects and clinical results.
30 Brainard et al. (1990) compared the effectiveness of treatment with white, red, or blue light. Eighteen outpatients with SAD participated in the study. Participants all had scores greater than 13 on the Hamilton Depression Rating Scale (HDRS) and met criteria on an additional rating scale of SAD symptoms. Patients were randomly assigned to 2 of the 3 light treatment conditions. The photon density for each light source was balanced. Three patients were assigned to each order of the light exposure. Light treatments consisted of exposure for two hours in the morning and in the evening for one week for each condition. There was at least one week in between each condition. The second condition was started when the patient scored nine points on the HDRS. To control for the placebo effect, as double-blind conditions were not possible, patient’s expectations of treatment were evaluated by a self-administered questionnaire after an explanation of the treatment and exposure to the light for two minutes. There was no significant difference in expectation for the three conditions. Data were analyzed for three groups of results: patients with a drop of 50% of greater on the HDRS for the second condition, a score of less than 8 on the HDRS after the second condition and, for the third group both patients with a drop of 50% of greater and a score of less than 8 on the HDRS. Results were considered significant only for the group with a 50% decline. A significantly greater number of patients had a 50% decline when exposed to white light compared with the red or blue light. These results indicate that exposure to red or blue monochromatic did not improve treatment efficacy over conventional full-spectrum white light. Oren et al. (1991) exposed 14 outpatients with SAD to red and green light. In addition to a diagnosis of SAD on a structured interview, a score of 13 or above on the HDRS was required. The patients were exposed to red light and green light for two hours
31 daily for one week each. They were randomly divided into two groups: red first or green first with at least one week each. Forty watt fluorescent bulbs, standardized for lux (~2500) and photon density, were used. Changes in the depression scale were significant only for the green light exposure. The group treated with green light for the first exposure had greater improvements in the depression scale compared with those treated with red light for the first condition. The group exposed to green light first showed the greatest improvement after the first condition. The mean scores decreased from 21 to 9 on the depression scale. These results indicated that brief exposure to green light reduces SAD symptoms to the normal range, thus alleviating the depression. The results for green light compare to results in previous studies using white light, showing that green light is also an effective intervention. This study examined two colors and did not compare the efficacy of these colors compared to white light for treatment of depression. Stewart et al. (1991) compared the effects of green light with white light in 12 patients with SAD. The patients met the criteria for SAD on the structured clinical interview for DSM-III and a score of 14 or higher on the Hamilton Depression Scale, Seasonal Affective Disorders Version. A self-administered scale was used to assess patients’ treatment expectations. Treatment consisted of two hours exposure to the light each morning for one week for each condition with at least one week in between. Results indicated that both the white and green light significantly reduced scores on both measures. White light was significantly more effective at reducing scores on items specifically related to SAD on the Hamilton Scale, thus demonstrating a narrow superiority of the white light treatment.
32 Subsequent investigation by Brainard et al. (2001) determined that the wavelength region of 446-477 nm was the most potent for suppression of melatonin secretion. This falls in the blue-green range. This suggests that blue-green light will be more effective as a treatment for SAD. Further clinical investigations are warranted to determine whether blue-green is the most effective treatment. Brainard et al. suggested that determining the action spectra for circadian effects may lead to improvements in light therapy. They report that current illuminance levels (2500 to 12,000 lux) sometimes cause side effects, such as visual fatigue, discomfort, and headaches, and they stated that “total illuminances for treating a given disorder can be reduced as the wavelength emissions of the therapeutic equipment are optimized” (p. 6411). Given results from the studies reviewed here, it appears that there is not always a direct correlation between melatonin suppression with light of 446-477 nm and the efficacy of clinical treatments. This points out one of the differences between basic research and clinical research. For example, Brainard et al. (2001) tested a random sample of individuals as opposed to a group with clinical depression. The results of his findings may not be of important clinical relevance. One factor may be that physiologically depression is more complicated than simply levels of melatonin. Nonocular Clinical Applications of Color Comprehensive systems of healing utilizing color on the outside of the body have been developed. Babbitt (1967/1878) utilized sunlight projected through specially designed, stained-glass windows. Babbitt created several devices. The chromo disc is a cone used to concentrate sunlight to a 5-inch diameter color filter to be placed on specific areas of the body. The chromo lens is a glass vial that holds 8 ounces of water to be
33 mixed with specifically recommended chemical compounds to create a colored lens through which to shine light onto the skin. Babbitt made specific color recommendations for a vast array of illnesses and disease states. He provided case histories for each of these treatments. During this same time period Seth Pancoast (1877, as cited in Pesner, 1996) and Augustus Pleasanton (1876, as cited in Pesner, 1996) published treatises on their use of color as medicine. Dinshaw Ghadiali developed spectro-chrome therapy in 1920 (Dinshaw, 2003). This system utilized colored filters placed over electric lamps. Specific color combinations placed over defined areas of the body were prescribed for 331 different disease conditions. Both Babbitt’s system and spectro-chrome assigned specific attributes to each color. In 1903, Auguste Rollier was operating 37 clinics treating tuberculosis with sunlight (Martin, 1998). In 1903, Niehls Ryberg Finsen won the Nobel Prize for his treatment of lupus vulgularis with light. He utilized sunlight or light from an electric arc lamp concentrated through a lens and directed at the localized lesions on the skin (Morner, 2002). My literature review focused on fairly recent research. Kuller (1981) provided an exhaustive annotated bibliography of research spanning several decades. Two additional reviews of research on colored light from the first half of the 20th century are found in a Master’s thesis by Nowak (1981) and in Birren (1997). Currently, there are various forms of medical treatment for physical conditions that utilize light in various ways. Blue light is used as a treatment for jaundice in infants (McDonagh & Lightner, 1985, as cited in Bloch, 1990). Ultraviolet light is used as treatment for psoriasis and acne (Martin, 1998).
34 These uses of blue light and UV light for these conditions are not considered experimental treatments. Low-level laser therapy is used for a range of conditions. (For a thorough bibliography of research, see http://www.drz.org/asp/cp/studies.htm). Light-emitting diodes (LEDs) have been shown to improve wound healing. These devices produce light in the far-infrared range (680 to 880 nm; Whelan et al., 2004). Infrared light increases microcirculation and is used for pain control (Pontinen, 2002). Photodynamic therapy is used as a treatment for cancer and nonmalignant conditions including macular degeneration (Huang, 2005). Although these techniques are fairly new, recently there have great advances in research and FDA approval for clinical treatments. Photodynamic therapy uses porphyrins, which are pigments found in animals and plants. They are involved in the formation of many important substances in the body including hemoglobin, which carries oxygen in the blood. Porphyrins have the ability to absorb light and pass its energy along to oxygen molecules dissolved in tissues (Kessel, 1998). They are used as a cancer treatment because when injected into the body, damage or death in the cancer cells will result when they are subsequently exposed to certain types of light (Kessel, 1998). Discussion A basic framework for the physiological mechanisms of the nonvisual response to colored light has been developed. Recent studies have investigated the response of the third photoreceptor and its photopigment. The operation of the circadian clock is dependent on light and controls the diurnal variation in many physiological processes. Effects of colored light on psychophysiology show concurrent reactions in the
35 hypothalamus and pineal gland. Some interesting alternative mechanisms, such as those involving the electromagnetic field, have also been proposed. In a few studies, colored light has been shown to reduce or increase levels of neurotransmitters and neurohormones. The differing psychophysiological effects of color across the spectrum of lesser to greater wavelengths has been investigated. Results appear to verify the theory of progressively greater arousal with longer wavelengths. Some studies have explored subjective responses to color. This is an area with rich possibilities for investigation. Quantifiable empirical evidence does not address the totality of human experience. Color is used to manipulate emotions and behavior in the fields of business and art, for example marketing and interior decorating. Further psychological analysis has clinical implications for both medicine and education. From the limited research, color preference in relationship to subjective and empirical response appears to be an important factor. Further examination of color preference is necessary to answer questions of universality versus individual variation in color response. Several therapeutic systems for treating both psychological and physical illness using color have been developed. There is a body of anecdotal evidence concerning the success of these methods. This anecdotal evidence spans the last 130 years. Controlled studies of clinical effectiveness are severely lacking. Many of the reports reviewed here used a very small sample size and provided no statistical analysis. Any greater scientific understanding and validation of therapeutic effects of colored light requires evidence gathered in a systematic way, with the most sophisticated psychophysiological and biological measurements.
36 Although full spectrum, white light is an effective treatment for SAD, several studies have examined the value of colored light for this condition. One factor, which confuses interpretation of research and clinical results, is the lack of standardization as a variety of different light sources with different properties are used. Intensity and wavelength are only two properties of light that must be considered. In addition, clinicians differ in their choice of time and frequency of exposure to the light. These factors are difficult to control and these limitations are inherent in experimental research. The addition of flashing or photic driving is another additional factor, which has effects of its own. One consideration that future investigations can elucidate is whether and in what instances colored light should be considered as a primary treatment or simply an adjunct to other forms of treatment. At this time, this decision will vary with each practitioner and with each patient. This portion of the literature review sampled a variety of human responses to colored light. The beginning of a foundation of knowledge has been laid. Color may be the earliest form of vibrational or energy medicine. Along with sound, light may also be one the simplest examples and readily available forms of this integrative approach. I hope this dissertation makes a contribution to the body of research that is clearly warranted to reveal and validate significant new medical benefits of these treatment approaches. Heart Rate Variability (HRV) This dissertation uses heart rate variability as the primary measure of autonomic functioning. The review of the literature covers background information about HRV, and the uses of HRV to measure autonomic functioning in a variety of conditions and situations.
37 History The historical precursor to HRV measurement goes back to the first part of the 18th century. Movements of the level of blood in a vertical glass pipe inserted into an artery of a live horse were regarded as indications of fluctuations of arterial pressure (Eckberg, 2000). Three other researchers observed fluctuations of arterial pressure in the 19th century (Eckberg, 2000). Just over 30 years ago, in a study using dogs, electrocardiogram (ECG) R-R intervals (the resting rate interval, which is also the interval of time between each heartbeat) were observed to correlate with vagal cardiac nerve activity (Eckberg, 2000). The vagal cardiac nerve is a measure of autonomic activity. Clinical relevance of HRV was observed in 1965, when it was observed that alterations in interbeat intervals preceded fetal distress (Task Force, 1996). These HRV changes occurred before any noticeable changes in heart rate. During the 1970s, HRV was shown to detect autonomic neuropathy in diabetic patients. In the 1980s, it was determined that a spectral analysis (using fast Fourier mathematical transformation of the R-R interval) of HRV could provide information about the specific functioning of the parasympathetic and sympathetic branches of the autonomic nervous system (Pomeranz et al., 1985). HRV was shown to be a clinical prognostic indicator as it was determined that there was a higher risk of mortality in myocardial infarction patients with reduced HRV (Task Force, 2000). Physiology The ANS is part of the central nervous system and is composed of two branches, the parasympathetic and the sympathetic nervous system. Among its functions, the ANS is responsible for the maintenance of homeostasis, the response of an organism to stress,
38 and adaptation phenomena (Koizumi & Brooks, 1980). Homeostasis is regulated by dynamic feedback between brain control centers and primary organs. There are both motor (efferent) and sensory (afferent) fibers. One analogy that provides a simplified way of understanding the physiological action of these two branches is to compare the ANS to the operation of an automobile. The action of the parasympathetic nervous system can be compared to stepping on the brakes, and the action of the sympathetic nervous system can be compared to pressing on the accelerator or the gas pedal of an automobile. The parasympathetic system promotes functions related to growth and restoration. The sympathetic system promotes increased metabolic output (Porges, 1995). The sympathetic system is involved in the flight-orfight stress response. Porges described stress as the “subjugation of internal needs in response to external demands” (p. 227). The parasympathetic system is involved in the “relaxation” response. Sympathetic and parasympathetic fibers have antagonistic effects on the heart. Sympathetic action is excitatory and “can accelerate pacemaker firing and conduction of excitatory impulses and increase the strength of contraction” (p. 899) of the cardiac system. Parasympathetic action is inhibitory and spontaneous depolarization of pacemaker cells is slowed (Koizimi & Brooks, 1980). The ANS primarily exercises its effect on the heart in the action of the vagal nerve, the 10th cranial nerve. Although there are vagal receptors throughout the entire heart, the vagal nerve primarily innervates the sino-atrial node. The vagal nerve originates in the brainstem in the nucleus ambiguous which regulates shifts in heart rate. Acetylcholine is the predominant neurotransmitter released at pre- and postganglionic terminals, in addition to neuropeptides. In addition, there is cortical, limbic control
39 (through the central nucleus of the amygdale, which regulates emotional lability), and endocrine control of the ANS (Porges, 1995). Mathematical Analysis Time series measures use simple descriptive statistics to analyze HRV. For example, to measure long-term variability (measurement over a 24-hour period) the standard deviation of the R-R intervals is calculated. Short-term variability (measurement over a 5-minute period) is calculated using the standard deviation of the mean consecutive difference of successive R-R intervals (Yeragani et al., 1991; see Table 2).
40 Table 2 Selected Frequency Domain Measures of HRV
Note. From “Heart Rate Variability: Standards of Measurement, Physiological Interpretation, and Clinical Use,” by Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology, 1996, Circulation, 93, p. 1041. Copyright by Lippincott, Williams & Wilkins.. Used with permission of the author/publisher. Power spectrum analysis of HRV was first developed in 1981 (Akselrod et al., 1981). Power spectrum analysis is a mathematical transformation of HRV data into a linear representation of frequency components. This can also be described as “the sum of elementary oscillatory components, defined by their frequency and amplitude” (Malliani, Pagani, Lomardi, & Cerutti, 1991, p. 482). These calculations use either a fast Fourier transformation technique or an autoregressive modeling on the raw data of
41 time between the heart beats. Although these two methods of analysis differ in their approaches to transforming the data (a descriptive method versus a statistical method), they do not consider the true nonlinear nature of heart rate variability. Yeragani (2000) utilized fractal dimension analysis, which takes into account the higher degree of complexity that exists in biological systems. Loss of complexity or increasing regularity is considered to be a sign of abnormality. Rao and Yeragani (2001) used other nonlinear methods that are assumed to represent complexity, predictability, and deviation from linear processes. Yeragani et al. (2001) utilized QT intervals from EKG data to obtain nonlinear measures. QT intervals represent the time of ventricular polarization and repolarization (Horst, 1999). Theoretical and Methodological Considerations The assumption of HRV measures as an indication of specific autonomic function is not without criticism. Malik and Camm (1993) cautioned that several factors influence vagal activity and sympathetic tone. High frequency components may be affected by conditions such as controlled respiration. High frequency components may not be a direct expression of vagal tone. Vaso and thermoregulatory mechanisms and such factors as the effects of moderate physical and mental exercise affect low frequency components. Kingwell et al. (1994) found several factors that influence HRV at 0.10 Hz. These include multiple neural reflexes, cardiac adrenergic receptor sensitivity, and electrochemical coupling. These factors are not directly related to cardiac sympathetic nerve-firing rates. Another factor that very much complicates the interpretation of studies that employ HRV measures is the lack of standardization of methodology. Studies may
42 employ 24-hour Holter recordings or 5-minute baseline and intervention conditions. Mechanisms and instruments used to measure heart rate also differ among the studies. Another factor that varies is the numerical definition of frequency ranges (Hz) of the components of the power spectrum. It is not known whether these factors discredit the conclusions that are drawn in the research. Cacioppo and Tassinary (1990) discussed several theoretical issues or obstacles in research using psychophysiological measurement technology. The first obstacle is the evolving state of signal acquisition. Cacioppo and Tassinary (1990) gave the example of the difference between electrodermal conductance and resistance. In a study of response to electric shock, measurement of skin resistance showed equal responses between subjects, whereas measurement of skin conductance yielded differences. It was assumed that resistance and conductance varied in inverse proportions. Similarly, there was a difference between groups when HRV was used as the measurement. A measurement may be responsive to factors that are irrelevant to the changes that they are assumed to measure. For example, prestimulus levels of sweat gland activity in electrodermal response or posture in HRV may distort the interpretation. A second obstacle concerns the “comprehensive representation and analysis of complex physiological signals” (Cacioppo & Tassinary, 1990, p. 17). Appropriate methods of analysis need to evolve and be developed to interpret properly and analyze the psychological measurements. For example, time domain HRV measures of data obtained by ECG recordings can be calculated using simple arithmetical or statistical formulas. Power spectrum analysis, which reveals more detailed and often useful information about the specific parasympathetic and sympathetic activity, requires fast
43 Fourier mathematical transformation, which has only been readily available fairly recently due to advances and accessibility of computer technology. In summary, it is necessary to look carefully at the specific conditions governing any specific measurement of psychophysiology to justify the interpretation in psychological processes. These issues highlight the fact that the use and understanding of HRV measurement is an evolving process. These issues do not preclude researchers from deriving useful information from HRV data. Research on Psychological Conditions There is a large body of research that uses HRV to study psychological conditions. This section reviews research that used HRV measures to study states such as mental stress, hypnosis, and emotions and to study conditions including anxiety disorders, depression, anorexia, alcoholism, and PTSD. Mental stress. HRV was used in a study of the effects of mental stress (Pagani et al., 1991). This study measured HRV by obtaining RR intervals from individual ECG recordings. Low frequency and high frequency power spectral density estimates were calculated. Participants in this study were 16 healthy male volunteers, and 9 male inpatients recovering from 1-month old uncomplicated myocardial infarctions (MI). Because these groups differed significantly in age (mean of 38 years versus 52 years) a third group of borderline essential hypertensive subjects (mean age of 55 years) were also included as a comparison to the post-MI group. Conditions included, in the following order, 5 minutes of controlled breathing, 10 minutes of rest, a 10-minute computerized attention task, 5 minutes of rest, followed by a semistructured interview, and for a subset of participants, a 5-minute handgrip test. The computerized attention test, designed to
44 create a state of mental stress involved viewing slides of a matrix of numbers with requirement of determining the presence or absence of one or both of two specified numbers. Negative acoustic reinforcement was given for wrong numbers and the timing of the presentation of the slides was varied to induce an approximately 50% error rate. The semistructured interview was performed by a psychologist and was aimed at arousing and confronting the participant. Overall results of this study indicated that the psychological stimuli of both the attention task and the interview induced marked increases in sympathetic activity for healthy and hypertensive subjects. These conclusions were based on observed increases in the LF power spectral density component. These increases in sympathetic activity were not seen in post-MI participants. It was noted that the limited sample size gives these results a provisional value. Hypnosis. HRV has been used to quantify the autonomic effects of the hypnotic state of consciousness (DeBenedittis, Cigada, Bianchi, Signorini, & Cerutti, 1994). Hypnosis is defined as a psychophysiological condition of focused attention. There is “a relative reduction of peripheral awareness and critical analytical mentation” (Wickramasekera, 1988, p. 5). The hypnotic state has been associated with the relaxation response, reduced sympathetic tone and enhanced parasympathetic activity, particularly, decreased heart rate, respiratory rate, and blood pressure (DeBenedittis et al., 1994). In this study, 10 participants were chosen out of 19 total possible participants on the basis of scoring as either high hypnotizable or low hypnotizable on the Stanford Hypnotic Susceptibility Scale: Form C. ECG was measured in an at-rest waking
45 baseline condition followed one week later by a neutral hypnosis condition. The hypnosis condition consisted of eliciting cooperation, progressive relaxation (relaxation and multi-sensory imagery), and arousal. Depth of hypnosis was verified by self-report of trance on a 1 to 10 scale of depth and by an independent observer. Frequency domains (low frequency: 0.03 to 0.15 Hz; high frequency: 0.18 to 0.35 Hz) were calculated from ECG data with an autoregressive approach. Time domain measures of R-R interval and the coefficient of variance were also calculated. Results revealed that hypnosis significantly increased R-R variance in high hypnotizable subjects. High hypnotizables generated higher variance than low hypnotizables. Hypnosis significantly decreased the low frequency to high frequency ratio, which indicates a shift toward parasympathic control during hypnosis. High as compared to low hypnotizable participants showed a greater decrease in the low to high frequency ratio. The power spectrum density of one of the high hypnotizable participants is shown in the report. Low frequency is reduced and high frequency is increased indicating a shift in power distribution from sympathetic to vagal parasympathetic dominance. These results provide further support of the hypothesis of functional reorganization of the autonomic balance observed in the relaxation response in neutral hypnosis. Emotional states. McCraty, Atkinson, Tiller, Rein, and Watkins (1995) used HRV to investigate autonomic response during two different emotional states. Twentyfour healthy participants were included in the study. Two contrasting emotional states were compared: anger and appreciation. All participants had been previously trained in a technique called Freeze Frame (McCraty, Atkinson, & Tomasino, 2001). This technique involves consciously disengaging from unpleasant mental and emotional
46 reactions and shifting attention to the heart area and feeling appreciation or a similar positive emotion. In this study, participants were asked to recall situations that aroused feelings of anger and/or frustration and to maintain these feelings for five minutes. In the second condition, following a 15-minute rest period, participants were asked to consciously experience appreciation. ECG recordings were taken and power spectral analysis was calculated for low frequency (0.01 to 0.08 Hz), middle frequency (0.08 to 0.15 Hz), and high frequency (0.15 to 0.5 Hz) bands. All three bands were summed to calculate total power. In addition, the ratio of low over high frequency and a ratio of medium frequency over low plus high frequency were also calculated. Results indicated that total power increased during both emotional states. Anger caused an increase only in low frequency in contrast to appreciation, which caused an increase in both low and high frequency bands, though the high frequency increase was not significant. The low to high frequency ratio (LF/HF) was significantly increased only during the anger state. Medium frequency was significantly increased during both conditions, although analysis of the power spectrum revealed a shift toward the medium frequency region during appreciation. The medium over low plus high frequency conditions showed a significant increase only for the appreciation condition. The results are interpreted to indicate an increase in sympathetic activity during the anger state. Medium frequency was believed to be an indirect indicator of activity in the baroreceptor feedback loop controlling blood pressure as well as mixed sympathetic and parasympathetic activity. The authors stated that because positive emotions lead to increases in total HRV and parasympathetic activity, they concluded that interventions
47 involving positive emotions may be beneficial in the treatment of hypertension and in reducing mortality in cardiac patients. Anxiety. Several studies have focused on HRV and conditions involving anxiety, including phobic anxiety and panic disorder. Kawachi, Sparrow, Vokonas, and Weiss (1995) investigated the relationship of phobic anxiety and heart rate variability. Participants were taken from a longitudinal normative aging study. The study participants were 581 men. Phobic anxiety was measured by the Crowne-Crisp index, an 8-item selfrated scale that includes common symptoms of phobias. In this study, HRV was measured by calculating two values, the standard deviation of heart rate and the maximal minus the minimal heart rate. This was calculated by subtracting the mean of six heart rate differences from one respiratory cycle. Participants were asked to breathe at a controlled rate of six breaths per minute for 25 respiratory cycles. Participants were divided into four groups based on their level of phobic anxiety. Results indicated significantly higher levels of phobic anxiety for participants with lower HRV on both measures. The analysis was adjusted for age, mean heart rate, and body mass index, which are all considered potential confounding factors. The researchers noted one caution in interpreting the data. High scores on the Crowne-Crisp index do not necessarily imply a clinical diagnosis of anxiety disorder. Thus, these results cannot be generalized to those diagnosed with anxiety disorder. This study was carried out to investigate the mechanisms by which phobic anxiety was associated with sudden cardiac death in previous studies (Kawachi et al., 1994). Kawachi et al. (1995) believed that the results of their study provided “plausibly clear” (p. 885) evidence that HRV is the
48 mechanism by which phobic anxiety is associated with increased risk of sudden cardiac death. Thayer, Friedman, and Borkovec (1996) measured HRV in 34 patients with generalized anxiety disorder and 32 nonanxious control participants under conditions of relaxation and of worry. Generalized anxiety disorder is associated with constant excessive muscle tension, elevated vigilance to threat cues, and poor attentional control. Worry is defined as greater amounts of thought as opposed to imaginal activity and excessive thought activity is a major characteristic of anxiety disorder patients. In this study, the patients had a DSM-III-R diagnosis of generalized anxiety disorder with a rating of moderate anxiety or greater with no panic or other psychological, neurological, or medical conditions known to produce anxiety. HRV data were obtained by ECG during a baseline period followed by a relaxation and a worry condition for both the patients and the controls. Participants were instructed to relax by focusing on breathing and allowing thoughts to wander and during the worry condition they were instructed to worry as intensely as possible on a topic preselected for each participant. Power spectral analysis was calculated for low (0.039–0.15 Hz) and high (0.18–0.35 Hz) frequency ranges. Results indicated that generalized anxiety disorder patients had higher low frequency and lower high frequency measures, indicating less parasympathetic activity for the patients in all conditions. During worry as compared to relaxation, both groups had similar higher low frequency and lower high frequency measures results indicating less cardiac parasympathetic activity during worry. Significant effects were seen in the lower high frequency measure, indicating that generalized anxiety disorder patients had
49 less cardiac parasympathetic activity than controls. These results were interpreted to indicate that weak parasympathetic control as opposed to strong sympathetic characterized the anxiety disorder patients. This can also be equated to rigid underreactive autonomic activity and decreased sympathetic tone. Thayer et al. (1996) concluded that this pattern should not be described as autonomic hyperactivity that had been previously applied to generalized anxiety disorder. Thayer et al. also discussed pilot research indicating positive changes in autonomic control seen in HRV measures after cognitive behavior therapy. Panic disorder. Panic disorder is another psychiatric condition involving anxiety. Studies have shown correlations between both panic disorder and recovery from panic disorder and HRV. Klein, Cnaani, Harel, Braun, and Ben-Haim (1995) measured HRV among 10 panic disorder patients and 14 healthy controls. HRV was chosen as a measure because, although it is not known whether somatic symptoms of panic disorder are related to a primary CNS event or an increased awareness and sensitivity to somatic events, the initiation and manifestation of panic disorders is intimately associated with the ANS. In this study, data were obtained by ECG. Power spectrum of HRV was obtained by analysis of beat-to-beat variations. An energy ratio index was calculated for each participant. The energy ratio index is another term for the LF/HF ratio. A higher energy ratio index indicates a shift toward sympathetic dominance. Results indicated that heart rate, the high frequency component, and the energy ratio index were higher in the panic disorder patients. An absolute decrease in the high frequency component of the power spectrum was found for the patients. Statistical
50 analyses were done to determine that higher heart rate in the patients did not account for the heart rate variability differences. Klein et al. (1995) concluded that these results indicate that panic disorder is associated with reductions in parasympathetic tone. This conclusion is not contradicted by a later finding using direct nerve recording and catecholamine kinetics (whole body and cardiac measurement), which found sympathetic nervous system activity is not elevated at rest nor globally activated during panic attacks (Dominic, Thompson, & Lambert, 1998). Klein et al. noted that the findings of their study apply only to panic disorders and further research is needed to determine whether these results generalize to other anxiety disorders. Middleton and Ashby (1995) examined recovery from panic disorder and accompanying changes in HRV as well as blood pressure response to standing and plasma noradrenaline levels. They sought to investigate the hypothesis that panic disorder is a “neurobiologically determined abnormality of arousal regulation” (p. 108) with impaired scrutiny of the focus of arousal as one of the psychological consequences. Twenty-two participants with panic disorder were included in the study. Participants were assessed before beginning treatment, 3 months into treatment and at 6 weeks after the conclusion of treatment. In addition to the three measures the Spielberger Anxiety Index was given. Treatment consisted of either cognitive therapy or administration of imipramine. Spectral derivatives of heart rate variability were calculated. The method of analysis was not reported. Recovery due to cognitive therapy was associated with a significant rise in overall HRV and peak frequency in the 0.1 Hz range. Significant effects of imipramine were only seen at mid-treatment, that is, while the patients were taking the medication.
51 There was reduced spectral power in the respiratory range and the 0.1 Hz range. Other findings of this study were a nonsignificant trend toward increased plasma noradrenaline in the imipramine treated group from before to after treatment. Blood pressure responses to standing rose from before to after treatment for both groups. These results confirm the hypothesis of changes in cardiovascular regulation among panic disorder patients as they recover. The authors interpret their findings as reflecting a possible correction of an abnormality of arousal regulation. Yeragani and Kumar (2000) investigated hostility and type-A personality in patients with panic disorder. Twenty-seven patients with panic disorder participated in the study. At baseline, participants were rated on standardized measures of trait anxiety, and type-A was calculated from a total of hostility, and impatience and hard-driving competitiveness scales on a standardized activity survey. Data on these measures was collected on a total of 14 patients and 4 controls. There was a 5-minute baseline with Holter ECG recordings. After 5 minutes of resting in a supine posture, 10 minutes of supine ECG was followed by 10 minutes of standing ECG was recorded. Ultra low frequency (< 0.0033 Hz), very low frequency (0.0033-0.04 Hz), low frequency (0.04– 0.15 Hz), and high frequency (0.15–0.5 Hz) power spectrum frequency bands were calculated. QT intervals, assumed to follow heart rate variability measures closely, were also calculated. In this study, the researchers hypothesized that both hostility and type-A behavior would be associated with decreased HRV (specifically, decreased ultra-low frequency and high frequency power and an increase in low to high frequency ratios). Panic disorder and depression. Yeragani et al. (1991) investigated HRV in 19 patients with major depression, 30 patients with panic disorder, and 20 healthy
52 controls. HRV was measured during three conditions, resting while supine (lying on their back), deep breathing while supine, and resting while standing. HRV was calculated from EKG recordings. Four time-domain measures were calculated. To measure long-term variability, the standard deviation of the R-R intervals was calculated. To measure short-term variability, the mean consecutive difference of successive R-R intervals and the standard deviation of this measure were calculated. A correction was made for heart rate in these measures. A fourth measure, assumed to be useful to study parasympathetic activity (PNN50), was the percentage of all the absolute differences of successive R-R intervals greater than 50ms. This was also corrected for heart rate. The main findings of this study were that there were no significant differences in standing HRV measures between depressed patients and controls. Similar to findings in other studies, panic disorder patients had significantly decreased standing HRV. Yeragani et al. (1991) noted as shortcomings of the study that they did not use a computerized program to detect the R-R intervals or spectral analysis to delineate sympathetic from parasympathetic functioning. In a subsequent study, Yeragani, Balon, Pohl, and Ramesh (1995) used power spectral analysis to analyze HRV in patients with panic disorder alone and patients with depression alone. ECG was measured in a supine position for 10 minutes followed by a 20-minute standing position. Low frequency was defined as 0.01 Hz to 0.05 Hz, midfrequency was defined as 0.07 Hz to 0.15 Hz, and high frequency was defined as 0.2 to 0.5 Hz. Absolute and relative power were also calculated.
53 Results indicated that relative midfrequency power was significantly higher in patients with panic disorder. This was interpreted as greater cardiac sympathetic activity in patients with panic disorder as compared to those with depression. The subjects were not matched for age which was considered a limiting factor in the study. The authors (1995) suggested further research with patients with both panic disorder and depression. Rechlin, Weis, Spitzer, and Kascha (1994) used time series and power spectral analysis to compare patients with panic disorder, major depression, and reactive depression. The patients with major depression were classified as melancholic type (three weeks after treatment with amitriptyline) and those with reactive depression (no psychotropic medications during the previous three weeks) had all attempted suicide within the previous 24 hours. The panic disorder patients also had not received psychotropic medication the previous three weeks and both the patients with reactive depression and those with panic attacks were undergoing psychotherapy. There were 16 patients in each of these three groups as well as a control group, also with 16 participants. HRV was measured in during four conditions: 5-minutes resting baseline; 120 beats during deep respiration; while blowing into mouthpiece maintaining a specific pressure and for 15 seconds afterward (Valsalva test), and before and after changing from supine to a standing position. The power spectral was divided into low frequency (0.02–0.05 Hz), medium frequency (0.05–0.15 Hz), and high frequency (0.15–0.50 Hz). Significant results indicated that panic disorder patients had a higher low frequency than controls, patients with major depression had lower high frequency than controls, and patients with major depression (treated with amitriptyline) differed
54 significantly from all other groups on all power spectrum indices. Rechlin et al. (1994) considered the lower heart rate variability of the amitryptaline patients to be due to its anticholinergic side effects. It concluded that the results suggest that patients with melancholic depression have reduced parasympathetic function and panic disorder patients have slightly increased sympathetic function. Depression. Using the same methods and analysis as the previous study (Rechlin et. al., 1994), Rechlin (1994) compared patients with major depression of the melancholic type, patients with dysthymia and controls. There were 26 participants in each group. Both groups of patients had been treated with amitryptiline for 14 days before the study. HRV was lower in all frequency ranges for both groups of patients compared to the control subjects. Patients with major depression had lower HRV in the mid- and high frequency ranges compared with patients with dysthymia (interpreted as parasympathetically controlled). It is suggested that amitryptiline treatment may unmask parasympathetic alteration in patients and possible underlying brainstem pathophysiology in patients with major depression. It is concluded that these results in addition to other measures of autonomic function may fulfill the criteria for a biological marker for major depression. Yeragani (2000) found similar results comparing a group of four patients with major depression to a group of 23 control participants. Twenty-four-hour Holter ECG recordings were collected in this study. Patients with major depression had decreased HRV on all power spectrum categories as well as lower total power.
55 Depression and coronary artery disease. Carney et al. (1995) investigated HRV in 19 coronary artery disease patients with major or minor depression. The patients with depression were compared to a matched group of coronary artery disease patients without depression. Coronary artery disease was defined as greater than 50% stenosis in one or more major coronary arteries. The researchers hypothesized that depression is associated with altered cardiac autonomic tone. HRV was obtained by a 24-hour ECG recording. Time domain measures of HRV were calculated, the standard deviation of all normal RR intervals (SDNN), as well as two measures of short-term variability (reflecting vagal influences), measure of intermediate variability was also significantly lower for the depressed patients. The remaining measures were lower but the results were not significant. These results confirmed Carney et al.’s (1995) hypothesis, although they noted that further research is necessary to determine whether HRV is the determining factor in the poorer prognosis of depressed coronary artery disease patients. Musselman, Evans, and Nemeroff (1998) recognized this point in their observation of HRV for all coronary artery disease patients, as they stated that HRV provides “clinically useful levels of negative predictive accuracy” (p. 584). They cautioned that positive predictive power is modest when taken in isolation or when considered in combination with other prognostic factors. Anorexia nervosa. HRV was used to study alterations in sympathovagal balance in anorexia nervosa (Petretta et al., 1997). Participants in the study were 13 women with a diagnosis of anorexia nervosa of the restricting according to DSM-IV criteria, 10 constitutionally thin women, and 10 women of normal weight. HRV data were
56 obtained by 24-hour Holter ECG recordings. Both time domain measures and frequency domain measures were calculated including SDNN and SDANN. Power spectrum analysis was calculated providing total power (0.00066 to 0.40 Hz) and for the bands ultra low frequency (0.00066 to 0.0033 Hz), very low frequency (VLF; 0.0033 to 0.04 Hz), low frequency (0.04 to 0.15 Hz), and high frequency (0.15 to 0.40 Hz). Some of the results of the study were that patients with anorexia nervosa showed longer NN intervals, and all time domain measures were higher than in both normal and thin women. For the power spectrum frequency measures, women with anorexia nervosa showed greater high frequency power than all other women. Also for thin women, low frequency power, ultra low frequency power and VLF as well as total power were lower than the other two groups. These results demonstrate greater parasympathetic cardiac activity throughout a 24-hour period. The time domain analyses are interpreted to suggest a sympathovagal imbalance with increased vagal tone. Petretta et al. (1997) also deduced from their results that patients with anorexia nervosa are characterized by increased cholinergic activity. They concluded that this change in sympathovagal balance (increased parasympathetic activity that is not a response to increased sympathetic activity) may be a contributing factor to the higher cardiovascular mortality of anorexia nervosa patients. Post-traumatic stress disorder (PTSD). Cohen et al. (1997) used HRV to investigate changes in ANS function, involving hyperarousal, in PTSD. These changes are both in basal tone and in reaction to stress related cues. PTSD patients and 9 controls participated in the study. Twenty-minute ECG recordings were obtained.
57 Power spectrum density and the integral of the low frequency (0.04 to 0.15 Hz) and high frequency (0.15 to 0.5) regions were calculated. Results indicated lower HRV (power spectrum density) for PTSD patients. Low frequency was higher and high frequency was low in PTSD as compared to controls. The results indicate low cardiac parasympathetic tone and elevated sympathetic activity at rest for PTSD patients. Cohen et al. (1997) discussed the possibility that their findings are characteristic of anxiety disorders in general. Alcoholism. HRV was used as a measure of cue-reactivity in alcoholics in a study by Rajan, Murthy, Ramakrishnan, Gangadhar, and Janakiramaiah (1998). It has been shown that alcoholics are conditioned to elicit autonomic arousal by the sight and smell of an alcoholic beverage. This cue reactivity as measured psychophysiologically is greater in alcoholics than in nonaddicticted individuals. Participants in this study were 20 inpatients with alcohol dependence and 23 social drinkers. Both time domain and power spectrum analysis were calculated from ECG recordings. The time domain measures computed were mean heart rate and the ratio of the SD of the R-R intervals to the mean (CVR). For the frequency domain analysis the following frequency bands were obtained: very low frequency (0.01 to 0.05 Hz), low frequency (0.05 to 0.15 Hz), and high frequency band (0.15 to 0.5 Hz). ECG was recorded for 4 minutes and 30 seconds after exposure first to a neutral cue (fruit juice) and then to an alcohol cue (rum). Results indicated no significant differences between the groups in response to the neutral cue. In response to the alcohol cue, alcoholics had significantly higher HRV measures as measured by CVR, very low frequency and low frequency. The two groups did not differ on mean heart rate. CVR is interpreted to indicate “higher magnitude of
58 short-term fluctuations of the cardiac interbeat interval” (Rajan et al., 1998, p. 545). Low frequency is interpreted to indicate greater sympathetic activity as a conditioned response for the alcoholic participants. Clinical implications for future studies using HRV measures were discussed. Prediction of relapse and the efficacy of treatment based on deconditioning principles are suggested as potential areas of study. Murata et al. (1994) investigated the acute and chronic effects of alcohol using HRV measures. To study the acute effects of alcohol intake, participants were 11 males all with a history of alcohol-induced facial flushing and a mean alcohol intake equivalent to 68 ml of 100% ethanol per week. They were given 200 ml of 25% ethanol. R-R intervals were recorded by ECG before ingesting the alcohol and at one hour and two hours after ingestion. The following day, similar measurements at the same times were taken with the ingestion of 200 ml of orange juice. To study the chronic effects of alcohol ingestion, 23 male patients with a DSM-III-R diagnosis of alcohol dependence were used. All of the patients had been drinking over the equivalent of 700 ml of 100% ethanol per week for 10 years. A control group consisting of 23 age-matched healthy males with alcohol consumption averaging 225 ml per week were used. HRV measures were taken one time. The ratio of the standard deviation of the R-R intervals to their average value was calculated (CVR-R). Power spectrum of the R-R intervals was calculated by autoregressive spectral analysis. A ratio of low frequency (0.05 to 0.15 Hz) to high frequency (0.15 to 0.3) was calculated. In the study of the acute effects of alcohol ingestion, CVR-R decreased significantly at one and two hours after alcohol ingestion and increased significantly one hour later. No significant changes in heart rate variability measures were seen after
59 the ingestion of orange juice. Results for the chronic alcohol patients were significantly lower on the CVR-R measures as well as the measures of low frequency and high frequency as compared to the controls. Murata et al. (1994) concluded that these results suggest that ethanol may affect higher centers of the ANS transiently, and parasympathetic vagal impulses may be reduced. The results provide information that suggests that chronic excessive alcohol ingestion and the neurotoxic effects of alcohol cause sympathetic as compared to parasympathetic dysfunction. In this study, HRV was used to study autonomic effects. The researchers suggested future research to compare autonomic with CNS measures of the effects of alcohol. Discussion One observation based on the methods of transformation and analysis of HRV data employed in these studies is that increasing power and accessibility of computer technology enables the evolution of these mathematically methods to correlate more closely with elements of the functioning of biological systems. The progress of the development of scientific knowledge from astronomy to biology has always been limited by available powers of observation. This review of studies provides support for the choice of HRV as the primary psychophysiological measure of autonomic function in this dissertation. I believe it is particularly well suited for this dissertation as correspondence of activation and relaxation with exposure to warm and cool colors can be observed fairly directly. Some of the earlier research provided evidence of HRV as a prognostic indicator of future health status (Task Force, 2000). More recent research clarified specific patterns of sympathetic and parasympathetic physiological activity in a variety of conditions and
60 diagnoses. This dissertation belongs in this category of research. I have found a smaller number of studies that used HRV to look at the effects of clinical treatments (e.g., psychotropic medications, psychotherapy; Rechlin et. al., 1994). Portable measures of HRV have the potential to identify short-term, long-term, and concurrent effects of almost any treatment modality. Although validation of colored light as a treatment modality is not a direct goal of this dissertation, the information that will result from the experiment can help to suggest further studies of a more clinical nature. If significant HRV changes are seen with a one-time short intervention, greater, more consistent, and longer lasting changes may be seen with a clinical protocol over many days. HRV can be an important tool to validate new or alternative therapies such as massage, acupuncture, and those involving subtle energies or conscious intent (e.g., prayer or visualization). This short-term measure of ANS processes offers a valuable addition to current outcome based research methods.
61 CHAPTER 3 METHOD Participants There were 20 participants in this study. Participants were required to be between the ages of 18 and 60 and included both males and females. The following exclusionary criteria were used: no history of grand mal seizures, head injury (an injury serious enough to cause unconsciousness), stroke, cardiovascular disease, and no current use of psychotropic medications, opiod painkillers, or antianxiety medications. Individuals who drank more than two cups of coffee less than three hours before the study were excluded. Participants were recruited using flyers posted on public bulletin boards in front of retail stores, at college campuses, and on a local activity Web site. In addition, potential participants were asked whether they knew of other individuals who might be interested in participating in the study. Compensation of $15.00 was provided for participation. The sample was a convenience sample and generalization to the population can only be made with a number of limitations and caution. Demographic data consisting of age, gender, ethnicity, and level of education were collected for all participants. Design This dissertation used a within-subjects experimental design or a counterbalanced design. In the counterbalanced design, all participants received all experimental treatments. In this study, the experimental treatment was the presentation of color (i.e., red or blue). The design involved a series of replications; in each replication the groups were changed, so in the end each group was exposed to every treatment. The order of exposure to the treatment was different for each group (Ary, Jacobs, & Razavieh, 2002).
62 The order of presentation was counterbalanced by order of color exposure. Half of the participants were randomly assigned to receive red as the first color condition and half of the participants received blue as the first color condition. This was to control for effects of order. Because treatments were administered to all groups, results obtained are generally not attributable to preexisting differences in the groups. All of the physiological measurements were taken for each of the five conditions (see Table3 )
Table 3 Basic Counterbalanced Design Replication O1a X1 Group 1 Pre-test Red 5 minutes 10 minutes Group 2
Pre-test 5 minutes
Blue 10 minutes
O1b Post/Pre-test 5 minutes
X2 Blue 10 minutes
O2b Post-test 5 minutes
Post/Pre-test 5 minutes
Red 10 minutes
Post-test 5 minutes
Measurement Psychophysiological Data Table 4 presents the psychophysiological measures that were collected on study participants. The Table 4 presents the acronyms used for the data, the actual names of the data, and a short definition for each psychophysiological data point.
63 Table 4 Definition of Dependent Variables Data Name Acronym
Definition/Meaning
Variability
pNN50
Very Low Frequency
VLF
% of adjacent interbeat intervals differing by > 50ms Sympathetic activation
Low Frequency
LFN
Sympathetic and Parasympathetic balance
High Frequency
HF
Parasympathetic activation
Total Power Total (of spectral analysis) Power Heart Rate HR
Total ANS output
Respiration
BR
Breaths per minute
Finger Temperature
Temp
Autonomic function
Heart beats per minute
The psychophysiological data were collected using the ProComp system produced bythe Thought Technology Corporation. The CardioPro software was used. This equipment was loaned to the researcher as a service by Thought Technology. This equipment is standardized medical instrumentation used in research and clinical work. The following sensors were used: finger thermister, respiration band, and EKG sensors. The EKG sensors provided measures of heart rate, EKG, and the interbeat interval (IBI). These data were analyzed by the CardioPro software to produce a table of the data listed above. The table provides an average over 5-minute epochs. Absorption The Tellegen Absorption Scale (TAS) is the most widely used measure of absorption. Absorption is a personality characteristic involving an openness to experience emotional and cognitive alterations across a variety of situations. The TAS consists of 34 true/false items. The TAS is reported to have good internal reliability (r =.88) and testretest reliability (r = .91; Tellegen & Atkinson, 1974). Kihlstrom et al. (1989)
64 characterized absorption as a trait marked by intense focus and unawareness of distracting stimuli. Several of the qualities of absorption measured with this scale may be related to the experience of looking at the colored light. These are responsiveness to engaging stimuli, responsiveness to inductive stimuli, and the ability to experience altered states of consciousness (Tellegen & Atkinson, 1974). State Anxiety State anxiety was measured using a 6-item short form of the Spielberger StateTrait Anxiety Inventory (STAI). The STAI is a frequently used measure of anxiety in behavioral research. According to Spielberger (1983), “Anxiety states are characterized by subjective feelings of tension, apprehension, nervousness, and worry, and by activation or arousal of the autonomic nervous system” (p. 4). The full-length STAI consists of 40 items. Marteau and Bekker (1992) developed a 6-item version with a correlations as high as r = .91 with the full-length STAI. The six items are characterized by the absence or presence of the following adjectives: calm, tense, upset, relaxed, content, and worried. The short form was chosen for this study because it enables administration three times: before the baseline condition (pretest), after the first color intervention, after the second color intervention, and after the post-test condition with minimal interruption Color Preference As a simple measure of color preference, participants were asked whether they preferred the first or the second color. The researcher determine which of the two color conditions most closely matched the label that the participant used. For example, blue may be labeled by the participant as aqua, violet, or indigo by the participant.
65 Procedure On entering the room, the researcher explained the study and any potential risks. The informed consent form (Appendix A) was explained. It was explained that participants may receive a summary report of the results of the study. Both the researcher and the study participant signed the consent form and a copy was filed in a place separate from the data for the study. Participant received a copy to take with them. Participants were given the demographic form to complete (Appendix B), and the Tellegen Absorption Scale. Upon completion, the participants were asked to sit in front of the light machine, which was adjusted for eye level. The researcher sat at a table in the same room in front of a laptop computer. The screen of the computer was outside of the view of the participant. The participant was told the following: Sensors will include an electrocardiogram (EKG), which will be placed on both forearms to measure the heartbeat and a sensor will be placed over one finger to measure skin temperature. A band will be placed around your abdomen to measure respiration. Participants were shown how to affix the respiration band around their abdomen (over their clothing) and asked to do so. Sensors were then placed on the forearms and on the fingers. The participant was then told the following: I am asking you to sit still with your eyes open for 5 minutes looking forward. I will turn on the machine and you will sit for 10 minutes looking at a color, answer some questions and then sit for 5 minutes with your eyes open, and then you will look at another color for 10 minutes, answer some questions and then sit again with your eyes open for 5 minutes. You don’t need to do anything in particular. Try not to move your arms too much.
66 Participants were then told, “Now you will sit still for five minutes with your eyes open.” After the first and the second 10-minute color conditions, the anxiety scale was readministered and the participant was told, “Now you will sit for five minutes with your eyes open.” The participant was then asked, “Which of the two colors did you prefer, the first color or the second color that was shown to you?” The sensors were then removed. Variables The independent variables were red and blue color exposure and absorption. The dependent variables were psychophysiological measurements, state anxiety, and color preference. Research Questions This study on reactions to colored light has posed a number of research questions. RQ1: Is there a significant difference in the autonomic nervous system measures when participants view red compared to blue light? If so, what are the characteristics of this pattern? It was expected that red light (R) would result in greater arousal than blue light (B). Previous studies and observations have shown an inverse relationship between wavelength and arousal with colors on the red side of the spectrum having a shorter wavelength than colors on the blue side of the spectrum. This would be evidenced by the following differences in physiological measures: VLF: Red > Blue LFN: Red > Blue HF: Blue > Red
67 HR: Red > Blue BR: Red > Blue Temp: Blue > Red Total Power and pNN50: Total Color (red + blue) > No Color (pretest + post-test1 + post-test2 conditions) RQ2: Is there a linear relationship between absorption and psychophysiological response? RQ3: Is there a linear relationship between anxiety and psychophysiological responses? RQ4: Is there a linear relationship between baseline anxiety and baseline psychophysiological response? Data Analysis A probability level of p = .05 was used as the criterion for determining significance. Hypotheses 1 and 2 were tested using a repeated measures analysis of variance. Post hoc contrasts were made to test where differences occurred. Repeated measures is a within subject analysis allowing testing of change over time. MannWhitney Tests were also used to test differences between the colors red and blue. Spearman Rank Order Correlations were used to test for linear relationships between anxiety and psychophysiological response and between absorption and psychophysiological response.
68 CHAPTER 4 RESULTS The purpose of this study was to investigate the effects of colored light on the ANS. Data were gathered for 20 participants. All participants were exposed to two different color conditions. The participants were divided into two equal groups. The sequence of colors (red or blue) was equally counterbalanced with Group 1 receiving red as the first color and Group 2 receiving blue as the first color. There were five conditions of 10 minutes each for all of the participants. These were (1) Baseline, (2) Color 1, (3) Post-test 1, (4) Color 2, (5) Post-test 2. Table 5 displays the frequency counts for selected demographic and other variables. About two thirds of the participants (65.0%) were female and one third were male (35%). The two groups did not differ significantly from each other (p = .16). Eighty percent of the participants had at least a bachelor’s degree. Ages ranged from 19 to 60 years (M = 40.85, SD = 13.99). The two groups did not significantly differ from each in age (p = .63). Participants were asked to rate their level of physical activity with 25% of the participants reporting low, 60% reporting medium, and 15% reporting high. The two groups did not differ significantly from each other for activity level (p = .77). Sixty percent of each group reported a preference for the blue light with 50% of Group 1 preferring blue and 70% of Group 2 preferring blue. The two groups did not differ significantly from each other for preference (p = .36).
69 Table 5 Frequency Counts for Selected Variables (N = 20) Variable
Category
%
n
Gender Male
7
35.0
13
65.0
4
20.0
13
65.0
Masters
3
15.0
19-29 years
6
30.0
30-49 years
5
25.0
50-60 years
9
45.0
Low
5
25.0
12
60.0
3
15.0
Red-Blue
10
50.0
Blue-Red
10
50.0
Red
8
40.0
Blue
12
60.0
Female Level of Education High School Bachelors
Age a
Level of Physical Activity
Medium High Stimuli Sequence Group
Color Preference
a
Age: M = 40.85, SD = 13.99.
70 Research Question One Research Question One asked, “Is there a significant difference in the autonomic nervous system measures when participants view red compared to blue light? If so, what are the characteristics of this pattern?” Table 6 displays the descriptive statistics for all 8 outcome measures at all 5 points in time (baseline, red color, middle baseline, blue color, and post-test baseline). Also in Table 6, the results of repeated measures ANOVA tests are displayed to examine whether significant differences (p < .05) were found. None of those differences were significant at the p < .05 level. The five scores for the participants’ finger temperature were found to be significantly different (p = .001). The Bonferroni correction, which is an adjustment for multiple statistical tests, was performed. This was done because as more tests are run on the same data set, the likelihood increases of getting a significant response by chance alone (Royal College of Surgeons). The subsequent Bonferroni tests found no significant differences among the temperature scores (Table 6).
Table 6 Descriptive Statistics for All Outcome Measures Including Significance Testing, Repeated Measures ANOVA with Bonferroni Adjusted Pairwise Comparisons (N = 20) Outcome
M
Low
SD
High
pNN50 Baseline a
0.06
0.06
0.00
0.20
pNN50 Red a
0.14
0.22
0.00
0.75
pNN50 Middle Baseline a
0.06
0.06
0.00
0.18
pNN50 Blue a
0.10
0.15
0.00
0.65
pNN50 Posttest Baseline a
0.07
0.07
0.00
0.26
71 Table 6, Cont’d. Outcome
M
b
254.41
156.08
27.29
657.71
VLF Red b
318.45
271.27
33.66
988.18
VLF Middle Baseline b
301.97
162.50
20.72
653.18
VLF Blue b
327.94
288.56
44.27
1120.92
VLF Posttest Baseline b
387.19
267.70
37.27
1084.49
LFN Baseline c
57.97
24.48
7.79
92.16
LFN Red c
62.27
25.57
10.69
93.87
LFN Middle Baseline c
63.49
26.58
17.22
94.13
LFN Blue c
62.67
21.29
13.15
89.40
LFN Posttest Baseline c
65.64
23.61
10.49
94.64
HF Baseline d
42.41
24.20
7.84
92.21
HF Red d
37.83
25.56
6.13
89.31
HF Middle Baseline d
36.49
26.60
5.87
82.78
HF Blue d
37.17
21.47
10.06
86.86
HF Posttest Baseline d
34.36
23.61
5.36
89.51
Total Power Baseline e
683.87
435.13
131.96
1,633.97
Total Power Red e
854.75
790.17
138.08
3,578.38
Total Power Middle Baseline e
826.12
572.14
96.93
1,955.27
Total Power Blue e
857.50
767.62
142.06
2,999.08
1,113.06
1,279.94
247.70
5,785.29
Heart Rate Baseline f
75.15
9.48
57.27
88.51
Heart Rate Red f
74.22
9.48
57.69
89.88
VLF Baseline
Total Power Posttest Baseline e
Low
SD
High
72 Table 6, Cont’d. Outcome
M
Low
SD
High
Heart Rate Middle Baseline f
74.57
9.64
57.84
91.35
Heart Rate Blue f
74.57
9.44
58.35
94.83
Heart Rate Posttest Baseline f
74.27
11.20
57.79
101.91
Respiration Baseline g
21.11
5.07
13.25
33.13
Respiration Red g
21.93
5.34
14.07
33.49
Respiration Middle Baseline g
22.88
5.57
13.70
32.67
Respiration Blue g
25.73
15.88
13.72
89.71
Respiration Posttest Baseline g
23.66
6.24
15.54
37.75
Temperature Baseline h
86.66
6.94
73.43
95.97
Temperature Red h
89.47
6.00
73.34
97.26
Temperature Middle Baseline h
89.96
6.17
73.61
95.97
Temperature Blue h
89.65
5.68
74.68
95.05
Temperature Posttest Baseline h
89.69
5.49
74.09
97.04
Note. a For pNN50, Repeated Measures ANOVA: F (4, 76) = 1.95, p = .11. No pairwise comparisons significantly different at the p < .05 level. b For VLF, Repeated Measures ANOVA: F (4, 76) = 1.42, p = .24. No pairwise comparisons significantly different at the p < .05 level. Note. c For LFN, Repeated Measures ANOVA: F (4, 76) = 1.96, p = .11. No pairwise comparisons significantly different at the p < .05 level. d For HF, Repeated Measures ANOVA: F (4, 76) = 2.19, p = .08. No pairwise comparisons significantly different at the p < .05 level. e For Total Power, Repeated Measures ANOVA: F (4, 76) = 2.21, p = .08. No pairwise comparisons significantly different at the p < .05 level. f For Heart Rate, Repeated Measures ANOVA: F (4, 76) = 0.51, p = .73. No pairwise comparisons significantly different at the p < .05 level. g For Respiration, Repeated Measures ANOVA: F (4, 76) = 1.20, p = .32. No pairwise comparisons significantly different at the p < .05 level. h For Temperature, Repeated Measures ANOVA: F (4, 76) = 5.01, p = .001. No pairwise comparisons significantly different at the p < .05 level.
73 Table 7 displays the eight Wilcoxon matched pair comparisons for the participants’ responses to the red light or blue light. None of the eight comparisons were significant at the p < .05.level. Table 7 Differences in Outcome Measures during Viewing Red or Blue Light. Wilcoxon Matched Pairs Tests (N = 20) Outcome Measure
M
SD
pNN50 Red
0.14
0.22
pNN50 Blue
0.10
0.15
VLF Red
318.45
271.27
VLF Blue
327.94
288.56
LFN Red
62.27
25.57
LFN Blue
62.67
21.29
HF Red
37.83
25.56
HF Blue
37.17
21.47
Total Power Red
854.75
790.17
Total Power Blue
857.50
767.62
Heart Rate Red
74.22
9.48
Heart Rate Blue
74.57
9.44
Respiration Red
21.93
5.34
Respiration Blue
25.73
15.88
Temperature Red
89.47
6.00
Temperature Blue
89.65
5.68
z
p 1.05
.29
0.60
.55
0.30
.77
0.34
.74
0.22
.82
0.52
.60
0.78
.43
0.56
.57
74 To examine this question further, Table 8 displays the results for eight additional Wilcoxon matched pairs tests. As the two colors did not differ significantly, the participants’ average color response was compared against the participants’ average baseline responses. This answers a further question of whether response to color differs from baseline (no color) response. The participants’ temperatures were significantly higher for the average color response when compared against the average baseline response (p = .03). Table 8 Differences in Outcome Measures for Average Color Response a with Average Baseline Response b, Wilcoxon Matched Pairs Tests (N = 20) Outcome Measure
M
SD
z
p
Average pNN50 Color Response
0.12
0.17
1.33
.18
Average pNN50 Base Response
0.06
0.06
Average VLF Color Response
323.20
260.38
0.67
.50
Average VLF Base Response
314.52
145.06
Average LFN Color Response
62.47
22.87
0.22
.82
Average LFN Base Response
62.36
23.44
Average HF Color Response
37.50
22.94
0.49
.63
Average HF Base Response
37.75
23.36
Average Total Power Color Response
856.13
751.74
1.12
.26
Average Total Power Base Response
874.35
691.80
Average Heart Rate Color Response
74.39
9.38
1.01
.31
Average Heart Rate Base Response
74.66
9.85
Average Respiration Color Response
23.83
8.90
0.78
.43
Average Respiration Base Response
22.55
5.20
Average Temperature Color Response
89.56
5.72
2.30
.03
Average Temperature Base Response
88.77
5.54
Note. a Outcome created by averaging the red and blue light scores b Outcome created by averaging the three baseline scores (pretest, middle and posttest)
75 Research Question Two Research Question Two asked, “Is there a linear relationship between absorption, as measured by the Tellegen Absorption Scale and psychophysiological response?” To test this, 4 difference scores were created for each of the 8 psychophysiological measures. The 8 psychophysiological measures are variability (pNN50), very low frequency (VLF), high frequency (HF), total power of spectral analysis (total power), heart rate (HR), respiration (BR), finger temperature (temp), which yielded a total of 32 response measures. Specifically, these four difference scores were: (1) average Color minus average baseline; (2) red minus blue; (3) red minus average baseline; and (4) blue minus average baseline. The participants’ absorption score as measured by the Tellegen Absorption Scale was correlated with these 32 response measures using Spearman rank-ordered correlations. None of the 32 correlations were significant (p < .05; Table 9). Also in Table 9 are Spearman rank-ordered correlations for the 32 response variables with the participants’ gender, education level, age and activity level. There were no significant correlations (p < .05) for gender, education or activity level (Table 9). The participants’ ages were significantly correlated (p < .05) with 3 of 32 responses. Specifically, older participants had higher scores for: temperature red minus blue (rs = .46); VLF blue minus average baseline (rs = .51); and In addition, older participants had lower scores for temperature blue minus average baseline (rs = -.53) (Table 9).
76 Table 9 Spearman Rank-Ordered Correlations for Psychophysiological Responses with Absorption and Other Demographic Variables (N = 20) Activity Response Variable
Absorption
Gender
a
Education
Age
Level
pNN50 Color minus Base
.27
.18
.12
.06
-.14
VLF Color minus Base
.12
-.32
.09
.38
.06
LFN Color minus Base
-.14
.03
.16
-.04
.02
HF Color minus Base
.14
.01
-.13
.05
.01
Total Power Color minus Base
.30
-.30
.01
.32
-.06
Heart Rate Color minus Base
.00
-.19
.11
.39
.23
Respiration Color minus Base
-.29
-.12
.00
.09
-.17
Temperature Color minus Base
-.04
.14
-.06
-.13
-.03
pNN50 Red minus Blue
-.04
-.05
-.09
.03
-.03
VLF Red minus Blue
-.10
-.03
-.05
-.09
-.34
LFN Red minus Blue
.17
-.32
-.36
-.23
.10
HF Red minus Blue
-.18
.26
.37
.25
-.15
Total Power Red minus Blue
-.17
-.15
-.10
-.07
-.24
Heart Rate Red minus Blue
.14
.21
.19
.01
-.07
Respiration Red minus Blue
.28
.12
-.07
.04
.31
Temperature Red minus Blue
.08
-.39
.07
.46
pNN50 Red minus Average Base
.14
.07
-.07
.01
-.14
VLF Red minus Average Base
-.02
-.23
-.04
.17
.00
LFN Red minus Average Base
-.03
-.35
-.16
-.07
.17
.01
.37
.16
.06
-.18
Base
.02
-.23
.01
.28
-.13
Heart Rate Red minus Average Base
.15
.12
.27
.27
.01
.03
-.05
-.03
.00
.14
-.12
-.01
.03
.15
-.01
pNN50 Blue minus Average Base
.39
.14
.19
.11
-.16
VLF Blue minus Average Base
.27
-.23
.25
.51
LFN Blue minus Average Base
-.19
.25
.22
-.03
-.02
.21
-.21
-.23
.01
.09
HF Red minus Average Base
*
-.04
Total Power Red minus Average
Respiration Red minus Average Base Temperature Red minus Average Base
HF Blue minus Average Base
*
.06
77 Table 9, Cont’d. Activity Response Variable
Absorption
Gender
a
Education
Age
Level
Total Power Blue minus Average Base
.24
.03
.18
.30
.12
-.12
-.26
-.09
.18
.21
-.41
-.06
.05
.02
-.24
.01
.32
-.27
-.53
Heart Rate Blue minus Average Base Respiration Blue minus Average Base Temperature Blue minus Average Base
*
*
.10
a
Note. Gender: 1 = Male 2 = Female, * p < .05.
Research Question Three Research Question Three asked, “Is there a linear relationship between anxiety as measured by the Short Form of the Spielberger State-Trait Anxiety Scale and the participants’ eight psychophysiological responses?” Table 10 displays the Spearman rank-ordered correlations between the participants’ anxiety scores and their 32 response measures. As a preliminary analysis, their three baseline scores (pretest, first post-test, and second post-test) correlated with the 32 response measures. Specifically, pretest anxiety was significantly correlated (p < 05) with 5 of 32 response measures. The first post-test measure was significantly correlated with 4 of 32 measures and the second posttest measure was significantly correlated with 8 of 32 measures (Table 10). Of primary interest were changes in anxiety across the three points in time. The first anxiety change score (first post-test minus pretest) was significantly correlated with 2 of 32 measures. Specifically, it was positively correlated with HF red minus blue (rs = .44) and respiration red minus blue (rs = -.51). A second anxiety change score was also
78 calculated by subtracting the first post-test score from the second post-test score. This change score was significantly correlated with 6 of 32 response variables. Specifically, it was positively correlated with: LFN red minus blue (rs = .65) and total power red minus blue (rs = .57). In addition, this second anxiety change score had significant negative correlations with HF red minus blue (rs = -.65), LFN blue minus average baseline (rs = .51), and total power blue minus average baseline (rs = -.62; Table 10).
Table 10 Spearman Rank-Ordered Correlations for Psychophysiological Responses with Anxiety Measures (N = 20) First Response Variable pNN50 Color minus Base
Pretest
Second
Post-test
.00
.21
VLF Color minus Base
-.21
-.52
LFN Color minus Base
-.09
Post-test
First
Second
Change
a
Change b
.18
.17
-.02
-.41
-.36
.03
.16
-.20
.07
-.18
.03
-.18
.11
-.02
.10
Total Power Color minus Base
-.29
-.48
-.24
-.20
Heart Rate Color minus Base
-.08
-.28
-.35
-.17
-.10
Respiration Color minus Base
.23
-.07
-.16
-.14
-.19
Temperature Color minus Base
.02
.09
.20
.04
.07
-.42
-.36
.00
-.08
-.10
.25 .65
*
-.65
* *
HF Color minus Base
*
-.55
*
pNN50 Red minus Blue
-.44
VLF Red minus Blue
-.01
-.10
.15
LFN Red minus Blue
.25
-.11
.47
*
-.43
-.26
.10
-.47
*
.44
Total Power Red minus Blue
.12
-.17
.47
*
-.20
.57
Heart Rate Red minus Blue
.44
*
.54
.10
.00
-.20
Respiration Red minus Blue
.49
*
-.05
-.03
-.51
Temperature Red minus Blue
.13
-.28
-.08
-.31
.08
pNN50 Red minus Average Base
-.22
-.12
-.01
.14
-.07
VLF Red minus Average Base
-.13
-.44
-.17
-.34
.18
LFN Red minus Average Base
.12
-.01
.19
-.30
.32
-.15
.01
-.18
.34
-.32
HF Red minus Blue
HF Red minus Average Base
*
*
*
*
*
-.01
79 Table 10, Cont’d. Response Variable
First
Second
First
Second
Pretest
Post-test
Post-test
Change a
Change b
-.08
-.31
-.02
-.25
.17
.27
.15
-.18
-.13
-.18
-.06
-.17
-.43
-.17
Total Power Red minus Average Base Heart Rate Red minus Average Base Respiration Red minus Average Base
.50
*
Temperature Red minus Average Base
.10
.00
.09
-.04
-.02
pNN50 Blue minus Average Base
.23
.38
.37
.12
.06
VLF Blue minus Average Base
-.11
-.37
-.50
*
-.24
-.23
LFN Blue minus Average Base
-.23
.13
-.46
*
.29
-.51
*
.27
-.09
.49
*
-.28
.49
*
-.27
-.15
-.79
*
-.02
-.62
*
-.25
-.07
.16
HF Blue minus Average Base Total Power Blue minus Average Base Heart Rate Blue minus Average Base
-.43
*
-.60
*
Respiration Blue minus Average Base
-.12
.07
-.07
.28
-.18
-.18
-.02
-.05
.08
-.07
Temperature Blue minus Average Base a
b
Note. First Change Score = First Post-test–Pretest. Second Change Score = Second Post-test–First Posttest. * p < .05.
Research Question Four Research Question Four asked, “Is there a linear relationship between baseline anxiety (as measured by the pretest score on the Short-Form of the Spielberger StateTrait Anxiety Scale) and the eight baseline psychophysiological responses?” Table 11 displays the Spearman rank-ordered correlations between the participants’ pretest anxiety score and the eight baseline measures. Although the eight correlations were in the expected direction, none of the eight correlations were significant at the p < .05 level of significance.
80 Table 11 Spearman Rank-Ordered Correlations Between Pretest Anxiety Score and Pretest Psychophysiological Measures (N = 20) Psychophysiological Measure pNN50
Pretest Anxiety -.40
VLF
.05
LFN
.41
HF
-.39
Total Power
-.05
Heart Rate
.34
Respiration
.30
Temperature
.30
Note. * p < .05.
Additional Findings Table 12 displays the Mann-Whitney Tests comparing the five anxiety measures based on the two presentation orders for the color stimuli. No differences were found between the two groups for pretest anxiety (p = .70) or for the second posttest anxiety score (p = .40). Participants who first saw the red color had higher first post-test anxiety scores (p = .07) than participants who first saw the blue light. For the first anxiety change score (first post-test score minus pretest anxiety), those in the red-blue sequence gained an average of 1.90 anxiety points while their blue-red counterparts declined an average of 1.10 anxiety points. This difference was significant at the p = .02 level. For the second anxiety change score (second post-test minus first post-test), those in the red-blue
81 sequence declined an average of 0.50 anxiety points while their blue-red counterparts gained an average of 3.30 anxiety points. This difference was also significant at the p = .02 level (Table 12). Table 12 Comparison of Anxiety Measures Based on Presentation Order of Color Stimuli, MannWhitney Tests (N = 20) Anxiety Score Pretest
First Post-test
Second Post-test
First Change Score a
Second Change Score b
Order
M
SD
Red-Blue
7.90
3.41
Blue-Red
8.70
2.21
Red-Blue
9.80
3.22
Blue-Red
7.60
1.43
Red-Blue
9.30
2.95
Blue-Red
10.90
3.96
Red-Blue
1.90
2.73
Blue-Red
-1.10
2.02
Red-Blue
-0.50
2.55
Blue-Red
3.30
z
p 0.39
.70
1.81
.07
0.84
.40
2.40
.02
2.40
.02
3.30
Note. a First Change Score = First Post-test–Pretest. b Second Change Score = Second Post-test–First Post-test.
82 CHAPTER 5 DISCUSSION Summary of Results The results of this study did not confirm the hypothesis (Research Question 1) that there would a difference in psychophysiological response between exposure to red or blue light. There was a significantly higher finger temperature during total color exposure compared to the condition of no color. This indicates greater autonomic relaxation in response to color; that is, participants were more relaxed while viewing the colors as compared to the no color conditions. The hypothesis (Research Question 2) that higher absorption scores would correlate with greater response to colored light was not supported. There were some correlation between absorption and psychophysiological response for older as compared to younger participants. Older participants had a greater relationship between their level of the trait of absorption and their physiological response. There were significant correlations between anxiety and no color conditions for several psychophysiological measures (Research Question 3). Thus there was a relationship between anxiety and physiology. Additionally, there was support for the correlations between changes in anxiety following color exposure. This concerned the question of whether changes in anxiety level were synonymous with changes in physiology. These results provide support for the use of measurement of anxiety along with measurement of physiology. No support was found for relationship between baseline anxiety and psychophysiological measures (Research Question 4). Additional findings concerned
83 changes in anxiety in response to color exposure independent of psychophysiological measures. There was a significant increase in anxiety following exposure to red and a decrease in anxiety following exposure to blue. Delimitations Delimitations of this study relate to the sample population chosen and how the choice of this population limits the generalizability of the results. The participants varied widely in age. The results may not generalize to a younger adult population or an elderly population. Participants were screened for particular health conditions in an attempt to gather a sample of healthy controls. Thus, any conclusions are not likely to apply to individuals with health problems, including psychological or neurological disorders. The fewer the number of participants, the less likely the study will generalize to the larger population. This study had a small sample size of 20 participants. This was particularly problematic given the large variability in the psychophysiological responses. Limitations Some of the limitations of this study include the of time course of the stimulus and the choice of the stimuli. The participants viewed each of the colors within a 35minute time period. Different results may have been obtained had the participants viewed each color on separate occasions separated by a greater period of time. This could be either a greater amount of time within the same session or the same day or even viewing the different colors on different days. In this dissertation, colored light was compared to a condition of no color or relative darkness. Some studies have compared white light with color (Gerard, 1958).
84 Different results may have been obtained had the color conditions been separated by white light. This study was a snapshot of effects in one session for a short time period. The administration of the colored light lasted for 10 minutes. Different results can be expected with longer exposure, perhaps 20 or 30 minutes. One factor in the choice of the 10minute duration is that longer periods of exposure may have become very uncomfortable for participants as they were required to sit still during the session. Another factor is that the exposure was for only one session. One would not expect a chronic or systemic illness to be affected by taking one pill nor for lasting changes to result. Psychological treatments, such as biofeedback or psychotherapy, are likewise not expected to be complete after one visit to a therapist. The standard course of treatment used by Downing (1996) was 20 sessions. Syntonic optometrists utilize a similar or greater number of sessions (College of Syntonic Optometry, 2001). This study was not designed to address follow-up or long-term effects of colored light exposure. This study measured a large number of dependent variables. When this is the case, a significant number might have attained that level by coincidence alone; that is, when probability is set at .05, then the probability is that 5 of 100 findings will be false positives (or by chance alone). A statistical correction for the large amount of data collected reduces the possibility of significant findings. Given the exploratory nature of the study, there was little information in the literature to guide a more specific choice of fewer measures. Another limitation was that two colors were chosen as the dependent variables. The results do not generalize to effects of other colors of the spectrum. The inclusion of
85 additional colors would have made counterbalancing the order of administration more difficult requiring a greater number of groups and participants to achieve the same statistical power. Design Considerations There are several ways this study could be improved and redesigned. The time of exposure to the colored light could be increased to 15 minutes. A greater number of participants could be chosen with a sample of at least 40 participants. The age range of the participants could be limited to 18 to 25 years of age. The number of dependent variables could be reduced. If there is great variability among the participants in HRV, the data could be analyzed in two groups with one group including participants above the median score on baseline total power of HRV and the other group below the median score. A different light stimulus utilizing narrow-band LED lights could be used. This newer device has been reported to be yield more effective results (F. McManemin, February 1, 2003, personal communication). A checklist of adjectives of mood states (e.g., calm, happy, excited) could be created and given to the participants after the final post-test condition. Participants could be asked to rank each mood state description for each of the colors. This dissertation addressed the question of whether exposure to two different colors results in different physiological and psychological response in healthy participants. To answer more directly the question of whether colored light is an effective clinical intervention, an ideal study would investigate the use of colored light as a clinical intervention. This study would use a population of at least 60 patients diagnosed with anxiety disorders. The population would be divided into two groups: generalized anxiety
86 disorder and panic disorder. The age range of the participants would be limited to ages 25 to 40. Participants on medication or with a co-occurring diagnosis of depression would be excluded. The intervention would consist of 18 sessions of 30 minutes duration of colored light in the blue-green range of the spectrum with a 10-minute, no-color condition preceding the colored light. The sessions would occur 3 times per week spaced out over 6 weeks. An LED light device emitting narrow band wavelength would be used. Psychophysiological measures would be limited to finger temperature, high frequency and low frequency of HRV. Structured psychiatric interviews and a profile of mood states would be administered at baseline, after 3 weeks, and after completion of the 18 sessions. An anxiety scale would be administered at baseline and immediately before and after each color session. The participants would be asked to keep a daily journal and fill out a daily self-rating checklist of anxiety symptoms. There are many challenges inherent in designing research. Much was learned in carrying out the present study that may guide future research design. Designing research involves considerations such as choosing what questions to answer based on existing knowledge, what population to sample, the parameters of the interventions, and how to measure the effects. One striking feature of the results of this study was the large amount of variability among the participants in HRV measures. For example, among the 20 participants, the lowest score for total power was 131.96 and the highest score was 1633.97 with a standard deviation of 435.13. This variability reduces the power of the statistical analysis and increases the probability of Type II error. In addition, statistical analysis and results by themselves do not determine clinical relevance. A statistically significant result may
87 not make a difference in the health status of the individual. Additionally, the outcome of the intervention may be similar to what might be expected as normal fluctuations. Future studies should take into account the likelihood of heterogeneity of HRV measures among the general population. HRV measures have not been standardized for research. Clinical use of HRV in biofeedback training relies on changes from baseline in the individual patient, not on comparisons among a normative group. The participants could be chosen based on baseline scores within a specific range. A larger sample size would enable grouping of participants into categories. The population could be divided into quartiles and analyzed separately. This study utilized healthy controls. Different results might be expected for participants with psychological or physical conditions. Less variability in psychophysiological measures may be seen with a specific patient population. In Gerard’s (1958) study, participants with greater baseline anxiety had greater disturbance in response to red as well as more relief in response to blue. In a sense, individuals with an illness or pathological condition may need the colored light more. The use of a patient population may more directly answer the question of clinical utility of colored light interventions. This study utilized an intervention with an instrument that utilized a full-spectrum bulb with colored glass filters. The frequency of the light was broadband, which means that a given color is made up of a range of frequencies. There are instruments available, such as the Chroma Light, which utilize light-emitting diodes (LEDs) as the light source (Dillon, 2007). The frequency of the light differs in that it is a narrower band of the spectrum. It is not known whether this type of light would have stronger effects, although
88 some clinicians do believe that this is more effective. Vazquez currently uses an LED source for his photodynamic therapy. (F. McManemin, personal communication, January 30, 2004). There are other variables of the stimulus that may affect the response. These include intensity and choice of color. The substitution of a color of a higher frequency, such as indigo for blue, may have shown greater differences in response. Liberman (1991) and other clinicians have discussed different frequencies creating balance. They do not use the same frequency or color for each patient. Vazquez (1996) utilizes an assessment to determine which colors to choose. If this individual specificity holds true, then greater effects will be seen if colors are chosen according to some criteria for each individual. McManemin (1995) found significant differences between HRV responses to redorange and indigo. One significant difference in that study was the inclusion of photic driving as the light stimulus flashed at the rate of 12 cycles per second. It may be that this in a way primed the participant to experience greater effects of the color itself. A frequency of 12 would entrain the brain in the SMR range, which is purported to induce a state of focused relaxation. This may be exactly the state that would enable an individual to be most receptive to the colored light stimulus. Clinicians have utilized photic driving as a key component of their approach (Downing, 1996; Vazquez, 1996). The addition of photic driving may have similar results as hypnosis, in which an altered state increases the patient’s amenability to perceptual or behavioral changes. Hypnosis has been shown to induce HRV and other psychophysiological changes (DeBenedittis et al., 1994). Two types of data were collected in this study, psychophysiological measurements and affective measurement. In the results, anxiety was significantly
89 affected by color, whereas most of the psychophysiological measurements did not show changes at a statistically significant level. Future studies could be enhanced by the inclusion of more of such measurements. Quantitative changes in psychophysiological measures, although necessary and important, cannot correlate directly with subjective impressions that vary greatly among individuals. For example, finger temperature is a measure of relaxation. One individual may report feeling relaxed after a 20% increase in finger temperature and another individual may report not feeling any difference. Less is known about the clinical relevance of short-term changes in specific HRV measures. Although qualitative data cannot replace objective quantitative data to validate a response or result, it can provide a window into what the experience of color feels like to an individual. Research needs to be guided by a thorough and appropriate choice of measurements. Aside from physiological measurements, for example, this study utilized only a simple measure of anxiety. No investigation of mood or cognitive associations to the colors was carried out. Gerard (1958) utilized affective descriptions in his study. Participants were asked to rate each color on adjective pairs such as, friendly-kind (more often chosen in response to blue) and warm-hot (more often chosen in response to red). A rich area of exploration would involve qualitative analysis of participant’s response. Participants could be asked to talk about their thoughts and sensations while viewing the color. Transcripts of these narratives could be analyzed for common themes or a phenomenological methodology could be used. More insight would be gained in an empirical fashion about the lived experience of color. Rockwell (2002, p. 80) provided this kind of information in her discussion of the results of the Maitri room program. For
90 example, one participant who meditated each day for one week’s time in the red room reported experiencing a sense of heart-piercing compassion afterwards. She reported greater clarity and logical thinking after completing the week’s exercise in the blue room. This study measured effects on the ANS. There are many possibilities for measuring effects on the central nervous system, endocrine, and immune systems. Salivary cortisol and other hormones could be measured such as was done by Shealy (1996). Future studies could utilize measurements of salivary IgA as a measure of immune function. Lehrl et al. (2007) measured effects on a simple cognitive task. This could be expanded to include a greater variety of tasks tapping into attention, alertness and cognitive capacity, and performance. A series of colored light treatments was shown to improve cognitive performance in a head injury survivor (1995) and syntonic optometrists regularly treat cognitive symptoms (College of Syntonic Optomety, 2001). Effects on the central nervous system could be examined with EEG and brain scans such as fMRI or SPECT. Great advances in technology and methodology have been made since Gerard (1958) calculated occipital alpha amplitude and alpha percentage in his experiment. Nineteen-channel qEEG now provides comprehensive information about brain wave patterns and has been correlated with both psychological and cognitive functions (Gordon & Konopka, 2005).
91 CHAPTER 6 CONCLUSION The literature on colored light indicates its usefulness for psychological and emotional healing. Physiological mechanisms such as the pathway for light’s effects on the endocrine system through the retinohypothalamic tract provide a basis for beginning to understand the critical ways that light influences health. Although there is not a great established body of research, several studies have produced positive results showing the effects of colored light, and white light is an accepted treatment for SAD. Clinical observations of practitioners from a variety of fields describe the effects of colored light for a range of both physical and emotional conditions. Like most novel research investigations, this study cast out a broad net and provides heuristic information for future research. This dissertation revealed some of the methodological and statistical issues that must be considered. This dissertation focused on HRV measurements. Results for this and other psychophysiological variables appear to have been affected by small sample size, the heterogeneity of the sample population, and large number of variables analyzed. Future research could be improved by taking these and other factors into account as well as measuring other parameters, such as immune function. Research with a clinical population, such as anxiety disorder patients, is suggested to more directly address the clinical utility of colored light interventions. The possibilities for measuring physiological processes, psychological response, and health outcomes of colored light interventions are great. Developments in both technology and clinical systems can only enhance the understanding and effectiveness of clinical treatments. Given its place as a tool for healing in many cultures throughout
92 ancient and modern history, the physiological basis and importance of light for the functioning of the body, and the ubiquitous presence of light and color in both the life of the individual and in society and culture, continued exploration of colored light as a modality for healing remains promising.
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102 APPENDIX A CONSENT TO PARTICIPATE IN RESEARCH Purpose: The purpose of this research is to measure the human physical and psychological response to exposure to colored light. This project is being conducted by Larry Honig, who is a graduate student of Saybrook Graduate School and Research Center as part of the requirements for a doctoral degree in Psychology. Principal Researcher: Larry Honig, MA 1039 N. Alamo Ave Tucson, AZ 85711 520 247-3622 Procedures: [1] This study involves the use of biofeedback equipment to measure your response to colored light viewed through the eyes. [2] Completion of these procedures will require approximately one hour. This will include connecting the sensors, sitting in front of the light projector with periods of rest before and after viewing the light. You will be asked to fill out a questionnaire and answer some questions. [3] Biofeedback equipment would include a sensor device, an electrocardiogram (EKG), will be placed on the forearm to measure the heartbeat. A sensor will be placed over one finger to measure skin temperature and another sensor will be placed on a finger of the other hand to measure skin response, which is measured by detecting perspiration on the skin. A band will be place around your abdomen to measure respiration. These devices are purely for measurement and no electrical current of any kind is sent toward the body. You will be asked to sit in front a machine, which projects a color through a two- inch circular lens. The light is at a low enough intensity to prevent any irritation to the eyes. Possible Risks and Safeguards: This study is designed to minimize as much as possible and potential physical, psychological, and social risks to you. Although very unlikely, there are always risks in research, which you are entitled to know in advance of giving your consent, as well as the safeguards to be taken by those who conduct the project to minimize the risks. It is possible that you will respond to the light with uncomfortable feelings, thoughts or memories will uncomfortable feelings or memories. I understand that:
103 [1] My participation shall in no way have any bearing on any employment status, or alter or deprive me of any or all services presently received in the institution and setting in which I participate, as well as those provided by the institutions sponsoring, funding, and providing oversight, inclusively, for this research project. [2] Although my identity shall be known to the principal researcher, all identifying information shall be not be included in the computer file generated by the biofeedback software. Identifying information will not appear on my written responses or any notes taken by the researcher. [3] My responses to the question and my written responses s will be pooled with others and all identifiers, such as names, addresses, telephone numbers and related information which might be used to identify me, will be given a number. [4] This consent form will be kept separate from the data I provide, in a locked briefcase to be housed in a protected and guarded location in an office for three years, known only to the principal researcher and research supervisor after which it will be destroyed. [5] The written data collected are to be kept anonymous, stored in a locked container accessible only to the principal researcher and research supervisor for three years after which it shall be destroyed. [6] Numerical, graphic and transcriptions of written responses data in the form of computer disks and files will be kept indefinitely for future research. [7] All the information I give will be kept confidential to the extent permitted by law. The information obtained from me will be examined in terms of group findings, and will be reported anonymously. [8] There is to be no individual feedback regarding my biofeedback measurements or written responses. Only general findings will be presented in a Summary Report of which I am entitled a copy, and my individual responses are to remain anonymous. [9] All personal information I provide associated with my identity will not be released to any other party without my explicit written permission. [10] If quotes of my responses are used in the research report for the course, as well as any and all future publications of these quotations, my identity shall remain anonymous, and at most make use of a fictitious name. [11] I have the right to refuse to answer any question asked of me.
104 [12] I have the right to refuse at any time to engage in any procedure requested of me. [13] I have the right to withdraw from participation at any time for any reason without stating my reason. [14] I have the right to participate without prejudice on the part of the principal researcher and other persons assisting the principal researcher. [15] It is possible that the procedures may bring to my mind thoughts or feelings of an emotional nature which may upset me. In the unlikely event that I should become upset or experience emotional distress from my participation, the principal researcher shall be available to me. He shall make every effort to minimize such an occurrence. However, should an upset occur and become sufficiently serious to warrant professional attention, as a condition of my participation in this study, I understand that a licensed professional will be made available to me. If I do not have such a person, the principal researcher will refer me and reasonable costs up to the first 2 visits will be paid by the principal researcher. [16] By my consent, I understand I am required to notify the principal researcher at the time of any serious emotional upset that may cause me to seek therapy and compensation for this upset. [17] I will receive a copy of this signed consent form for my records. Regarding any concern and serious upset, you may contact the principal researcher at: 520 247-3622. You may also contact the Research Supervisor of the project, Jeanne Achterberg, Ph.D. at Saybrook Graduate School, 1-800-825-4480, 747 Front St., 3rd Floor, San Francisco, CA 94111. Should you have any concerns regarding the conduct and procedures of this research project that are not addressed to your satisfaction by the principal researcher and his or her research supervisor, you may report and discuss them with Arne Collen, Ph.D., the Chair of the Saybrook Institutional Review Board at Saybrook Graduate School, 1-800-825-4480, 747 Front St., 3rd Floor, San Francisco, CA 94111. Benefits: I understand that my participation in this study may have possible and potential benefits. [1] My participation may enable the principal researcher and others working in the topic area to make a contribution to knowledge and theory of colored light and its physiological and psychological effects. [2] Through future communications, future research and possible development and applications of the findings of the research, indirectly my participation may bring future benefits to the health and well-being of individuals. Summary Report:
105 Upon conclusion of this study, a summary report of the general findings will become available. If you would like a copy of the report, please provide the address to which you would like it sent. _________________________________________________ Postal address or e-mail address _________________________________________________ City, State and zip code Consent of Principal Investigator: I have explained the above procedures and conditions to this study, and provided an opportunity for the research participant to ask questions and have attempted to provide satisfactory answers to all questions that have been asked in the course of this explanation. ________________________________________________________________________ Signature Date _________________________________________________ Print name Consent of the Participant: If you have any questions of the principal researcher at this point, please take this opportunity to have them answered before granting your consent. If you are ready to provide your consent, read the statement below, then sign, and print your name and date on the line below. I have read the above information, have had an opportunity to ask questions about any and all aspects of this study, and give my voluntary consent to participate. ________________________________________________________________________ Signature Date _________________________________________________ Print name
106 APPENDIX B GENERAL INFORMATION FORM Age: ___________ Gender: ________ Race/ethnicity: ______________________________________ Education level: _________________________________________________________ Occupation: _____________________________________________________________ Do you have any current or chronic medical illness, if so please list them ? _____________________________ Have you ever had or doing you currently suffer from psychiatric or mental illness, please explain? _____________________________ Do you have any history of neurological condition such as head injury, epilepsy, attention deficit disorder or stroke? ___________________________________ Do you take any prescribed or over the counter medications ? (If so, please list and when last taken ) ______________________________________________________________ How much caffeine have you had today, that is how much coffee, tea or caffeinated soda, and how many hours ago did you drink these beverages ? Would you describe your level of physical activity as low, medium or high? __________ Are you colorblind ? ___________
107 APPENDIX C RECRUITMENT FLYER
Volunteers wanted for research study on response to colored light Prospective volunteers need to be age 18 years or older with no history of heart disease, stroke, attention deficit disorder, past or current psychiatric illness. They must not be taking any psychiatric medications. Colorblind individuals may not participate in this study. The study will take approximately one hour. The study will involve noninvasive measurement of physiological functions such as heart rate and respiration with biofeedback equipment while looking at colored light. The principal researcher is conducting this study as part of his requirements for completing his doctoral degree in psychology at Saybrook Graduate School and Research Center in San Francisco. Compensation will be provided for your time. If you interested in participating or have any questions, please call Larry Honig at (520) 247-3622.
108 APPENDIX D SHORT FORM OF THE SPIELBERGER STATE-TRAIT ANXIETY SCALE
Not at all 1
Somewhat Moderately So Very Much So 2 3 4
1. I feel calm
pre
Post1
Post2
2. I feel tense
pre
Post1
Post2
3. I feel worried
pre
Post1
Post2
4. I feel relaxed
pre
Post1
Post2
5. I feel content
pre
Post1
Post2
6. I feel upset
pre
Post1
Post2
109 APPENDIX E TELLEGEN ABSORPTION SCALE
