[Seasonal rhythm of melatonin in manic depressive patients].

Melatonin is secreted by the pineal gland with a circadian and a circannual rhythm. For some authors the circadian rhythm is modified during depressive states. The present study evaluates the melatonin circannual rhythm in five manic-depressive patients. Each patient is clinically and biologically evaluated every month during one year. The results of the present study show a lack of clinical relapse and a lack of seasonal variation of plasma melatonin level.