Psychophysiological Effects of Colored Light Used in Healing
Naveen K. Visweswaraiah and Shirley Telles

 

Abstract: Chromotherapy uses colored light for healing. The present study assessed the physiological effects of blue and red light in normal volunteers, as these colors were believed to have opposite physiological effects. Fifteen male volunteers (age range 17 to 29 years) were studied in two sessions each. Each session lasted for 40 min, with a test period of 30 min, preceded and followed by two 5-min periods without colored light. Throughout both sessions, subjects lay supine with eyes closed. The room was illuminated with ordinary light during the pre and post periods of both sessions. During the test period, blue light was used for one session, while red light was used for the other. The heart rate, skin resistance, finger plethysmogram amplitude, breath rate, blood pressure and electroencephalogram (EEG) were measured. There was a significant reduction in the breath rate during exposure to blue light and the diastolic blood pressure reduced immediately after exposure to blue light, compared to the preceding period (t-test for paired data). The results suggest that blue light reduces physiological arousal, supporting the claim that blue light can be used to induce physiological rest. Red light did not have a stimulating effect in this study.

INTRODUCTION

Chromotherapy or color therapy uses color (usually in the form of colored light) to produce beneficial or healing effect [1]. It is well established that color may be used to help people feel physically and emotionally more comfortable in their surroundings [2]. There have been reports that the mean anxiety and stress scores were higher for subjects who remained in an office with red walls, whereas the mean depression score was higher for subjects who stayed in an office with blue walls [3]. It was also shown that following exposure to red color, there was a reduction in skin resistance [4], suggesting increased sympathetic activity. In contrast, blue or violet colored rooms were correlated with lowest and most stable blood pressure readings [3].
The reports cited above discussed the effects of colors when the subject was viewing them. In chromotherapy, colored lights are used while the subjects' eyes are closed [5]. Light transmission through the eyelids has been estimated with a visual threshold response and was found to vary according to the wavelength [6]. Estimated light transmission was different for different colors, viz., 0.3% for blue, 0.3% for green and 5.6% for red light. The present study was designed to assess the physiological effects of exposure to colored light when the subjects’ eyes were closed, as used in chromotherapy. Blue and red light were specifically selected, as they are believed to have opposite physiological effects. Based on this assumption blue light is used to manage insomnia, while red light is used for depression [1].