Melatonin and Food

• Generic Name: melatonin
• Dosage Forms: n.a.
• Other Brand Names:

Melatonin is the natural hormone your body secretes that helps to maintain your wake-sleep cycle (also called “biological clock”). The wake-sleep cycle is the process of sleep and wakefulness; in humans this averages 8 hours of nighttime sleep and 16 hours of daytime activity. Melatonin is also made synthetically and available without a prescription as an over-the-counter (OTC) dietary supplement in the U.S.

Endogenous melatonin release (made by our bodies) is increased each day in response to darkness, peaking between 11PM and 3AM at roughly 200 picograms (pg) per mL. Nighttime levels are roughly 10 times higher than in the daytime. Levels fall sharply before daylight, and are barely detectable in the daylight hours. The rise and fall in endogenous levels signal wake and sleep times, known as our circadian rhythm.

Natural secretion starts from the amino acid tryptophan, with serotonin as an intermediary, and then is released to the receptors in the brain, eye and other areas to help control the sleep and wake cycles. The half-life is short, roughly 20 to 50 minutes. It is metabolized (broken down) by the CYP-450 enzyme system in the liver and then excreted in the urine or feces.

Shorter periods of production occur in the summer with longer days, and more prolonged periods of production occur in the winter. Light at night (such as from smartphones or the TV) blocks production and can lead to sleep disturbances. Age also suppresses the levels of nighttime melatonin that are released, which may contribute to the problem of insomnia and early awakening often seen in older adults.

Melatonin supplementation has been suggested to have many uses, from sleep disorders to cancer treatment , but robust studies are lacking for many uses. However, it has been widely studied for treatment of jet lag and other sleep disorders. Additional, early research to define melatonin suggests it has an anti-oxidative activity, a role in modulating immune responses, and possible anti-tumor activity.