Combining bright light with melatonin produces greater advance in circadian timing

A study in the November issue of the journal Sleep shows that morning bright light combined with early evening melatonin induced a greater phase advance of the salivary dim light melatonin onset (DLMO) than either treatment alone. The results suggest that information from light and melatonin is combined by the human circadian clock.  According to the authors, the findings may aid the development of effective countermeasures for jet lag, shift work and other circadian rhythm sleep disorders.