Manic episode induced by melatonin: a case report.

Melatonin is centrally synthesized by a neuroendocrine organ, the pineal gland. Its release into the circulatory system is stimulated by the onset of darkness, and it exhibits a progressive decrease in blood levels with the onset of dawn. Melatonin has been extensively studied in the treatment of sleep disorders, and there has been an accumulation of evidence of the possible role of melatonin in influencing mood. Measurement of melatonin either in saliva or plasma has documented significant alterations in depressive patients during the acute phase of illness.