Melatonin: Multifaceted messenger to the masses

This is the third article in a five-part continuing education series on chronobiology. Other articles focus on chronobiology's relation to the endocrine system, myocardial infarction, and chronopharmacology in cancer medicine. This article focuses on melatonin, the hormonal product of a small part of the brain called the pineal gland. The reader will learn how melatonin passes important time-of-day and seasonal information to all cells. This indoleamine is a highly conserved molecule that may exist in organisms ranging from algae to humans. Melatonin is produced and released from the pineal gland into the blood especially at night and is referred to as the chemical experience of darkness. Melatonin readily gains access to every fluid and cell in the organism. It also functions in the control of endocrine and reproductive physiology, and has been shown to be a potent free-radical scavenger.