SLEEP-PROMOTING EFFECTS OF MELATONIN - AT WHAT DOSE, IN WHOM, UNDER WHAT CONDITIONS, AND BY WHAT MECHANISMS

Differing conclusions regarding the sleep-promoting effects of melaton in may be the result of the broad range of doses employed (0.1-2000 mg ), the differing categories of subjects tested (normal subjects, insom niac patients, elderly, etc.), and the varying times of administration (for daytime vs. nighttime sleep). We conclude that melatonin may ben efit sleep by correcting circadian phase abnormalities and/or by a mod est direct soporific effect that is most evident following daytime adm inistration to younger subjects. We speculate that these effects are m ediated by interactions with specific receptors concentrated in the su prachiasmatic nucleus (SCN) that result in resetting of the circadian pacemaker and/or attenuation of an SCN-dependent circadian alerting pr ocess.