EFFICACY OF MELATONIN TREATMENT IN JET-LAG, SHIFT WORK, AND BLINDNESS

Melatonin has chronobiotic properties in humans. It is able to phase s hift strongly endogenous rhythms, such as core temperature and its own endogenous rhythm, together with the sleep-wake cycle. Its ability to synchronize free-running rhythms has not been fully investigated in h umans. There is evidence for synchronization of the sleep-wake cycle, but the available data suggest that it is less effective with regard t o endogenous melatonin and core temperature rhythms. When suitably tim ed, most studies indicate that fast release preparations are able to h asten adaptation to phase shift in both field and simulation studies o f jet lag and shift work. Both subjective and objective measures suppo rt this statement. However, not all studies have been successful. Care ful evaluation of the effects on work-related performance is required. When used to alleviate the non-24-h sleep-wake disorder in blind subj ects, again most studies report a successful outcome using behavioral measures, albeit in a small number of individuals. The present data su ggest, however, that although sleep-wake can be stabilized to 24 h, en trainment of other rhythms is exceptionally rare.