Light mask 500 lux treatment for delayed sleep phase syndrome

1. Bright light exposure has been demonstrated as an effective treatment fo r circadian rhythm sleep disorders. Recent studies suggest that more modera te intensities of light might affect endogenous rhythms. A light mask treat ment, using light applied through eyelids during sleep, was tested for Dela yed Sleep Phase Syndrome. 2. The active light group (n=5) received <(500 lux)under bar> light for 3 h ours prior to awakening for 12 days. The placebo light group (n=5) received <(0.1 lux)under bar> light with the same timing. Circadian rhythm phase wa s assessed from core body temperature and urinary 6-sulfatoxymelatonin meas urements. The SIGH-SAD-SR mood scale was administered to assess mood. 3. There were slight trends toward a phase advance of the body temperature rhythm and a phase delay of the melatonin rhythm, and both groups reported anti-depressant benefits. However, no statistically significant effects of 500 lux light mask treatment were demonstrated compared with the placebo-li ght treatment. 4. More extensive studies will be required to clarify the factors of dose-r esponse and phase-response.