Psychophysiological effects of colored light used in healing.

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.