Melatonin and psychiatry.

The pineal methoxyindole melatonin remains the most widely studied of the "pineal principles," and in subhuman species, the neuroendocrine status of this hormone is now generally acknowledged. In humans, however, no definitive functional activity for melatonin has yet been convincingly demonstrated, despite the description in recent years of marked changes in the metabolism of this hormone in several clinical categories. Currently, much interest is focused on the role that melatonin may play in various psychiatric disorders, and pineal research now represents one of the active areas of current psychiatry research. Investigators in this field have encountered many technical and practical difficulties, but the advent of the impressively sensitive and specific assay systems for melatonin has done much to facilitate the progress of research. Present ideas suggest a positive involvement of melatonin in affective disorders, possible involvement in the schizophrenic psychosis, and potential involvement of this hormone in other psychiatric categories. The present review discusses the etiological significance, diagnostic potential, and clinical utility of melatonin in psychiatry.