30 YEARS OF HUMAN PINEAL RESEARCH - DO WE KNOW ITS CLINICAL RELEVANCE

A role for melatonin in humans is becoming evident in an increasing nu mber of clinical situations. Marked variations in the magnitude of the nocturnal melatonin peak are observed throughout the human lifespan. The highest levels occur in children and then fall during puberty and further during adulthood. A negative correlation between circulating m elatonin and sex steroids has been observed in a number of instances, and appears to be independent of concomitant gonadotrophins. No clear melatonin pattern has been observed in pituitary tumors, but in large lesions that involve the hypothalamus, a reduced nocturnal rise has be en reported. Reported effects of exogenously administered melatonin ar e variable, probably reflecting differences in dose and timing; a slig ht stimulation of prolactin, as well as a partial inhibition of gonado trophins, has been reported, which explains its utility as an oral con traceptive, associated with a progestogen. A potential clinical use of melatonin as an oncostatic drug still awaits confirmation, although e xperimental data firmly support this possibility. The indole has also been used to hasten entrainment of subjects travelling across various time zones, and has been found to be specially useful in eastward trav el. Finally, changes in the normal melatonin circadian pattern have be en reported in psychiatric diseases and in sudden infant death syndrom e.