Melatonin, the hormone naturally produced by the pineal gland, has become one of the rages in health food stores. Besides melatonin's ever-growing use against jet lag, it is also touted as a remedy for sleeping disorders and depression, and as an inhibitor of the aging process. But what are the biological functions of melatonin already produced naturally within organisms?

This dialogue addresses this question. Participants described the history of melatonin research, showing how scientists from diverse disciplines - reproductive physiology, chronobiology, psychiatry, enzymology, and even dermatology - added to our understanding of melatonin action. They recounted many differences among species in both melatonin production and function, differences that unexpectedly made many animal species inappropriate model systems for establishing general principles about the hormone's function. Finally the discussants considered the major gaps in knowledge about melatonin, both at the molecular and physiological levels, and how such gaps might be filled.