Melatonin is a methoxyindole hormone that is produced in the pineal gland in the brain. It is synthesized from L-tryptophan in the diet, which is converted into 5- hydroxytrytophan then into melatonin. Melatonin is reported to help regulate sleep/wake cycles and circadian rhythms including cortisol patterns. Melatonin also helps improve immunity and is an antioxidant.
Melatonin levels decrease with increasing age. Other conditions that may lower melatonin levels include jet lag, night shift working, chronic stress and some medications.