Featured Questions, Comments and Responses

Subject: EM-COM
Question: Is melatonin taken to aid sleep an "endocrine disruptor"?
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Answer: Melatonin, the major hormone produced by the pineal gland, displays characteristic daily and seasonal patterns of secretion. In mammals, the night-time production of melatonin is mainly driven by the circadian clock, situated in the suprachiasmatic nucleus of the hypothalamus, which controls the release of norepinephrine from the dense pineal sympathetic afferents. Melatonin acts via a G-protein signaling system, antagonizing the intracellular release of cAMP. Melatonin receptors have also been characterized in many peripheral structures such as the spleen, testis, ovary, vascular system, gut, smooth muscle, and some cells of the immune system, though the role of melatonin in these glands and systems is not understood.

It is unclear whether melatonin is affected by endocrine disrupting chemicals. The mechanism of action of melatonin remains to be fully elucidated, followed by a greater understanding of the role of melatonin in the reproductive and other physiological systems.