ABSTRACT
Some sleep problems are due to abnormal timing of the circadian system. Circadian rhythmsleep disorders can be treated with appropriately timed bright light which normalizescircadian rhythm timing. Some evidence in animals and humans suggests that the circadian system may be differentially sensitive to colored light. We compared the efficacy of broad-band white light as well as short and long wavelength light in suppressing nocturnal melatonin and retiming the melatonin onset, a reliable time marker of the endogenous human circadian system. Results show the human melatonin circadian system is more responsive to shorter blue and green wavelengths of light than the longer amber and red wavelengths. These results suggest a more effective treatment for these sleep problems.
