Melatonin is the natural hormone your body secretes that helps to maintain your wake-sleep cycle (also called “biological clock”). Melatonin is also made synthetically and available without a prescription as an over-the-counter (OTC) dietary supplement in the U.S.
Melatonin is most commonly used to:
help decrease jet lag
adjust sleep cycles in the blind (non 24-Hour Sleep Wake Disorder, or Non-24)
treat shift-work sleep disorders in people with alternating work schedules
for general insomnias
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 supplementation has been suggested to have many uses, from sleep disorders to cancer treatment, but adequate studies are lacking for many uses.
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.
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.
How Does Melatonin Work?
Natural melatonin is a highly lipid soluble hormone produced in the pineal gland in the brain. It is synthesized from the amino acid tryptophan and then released into the blood and cerebrospinal fluid, crossing the blood-brain barrier. It sends messages to the receptor agonist in the brain and other areas of the body to help control the sleep and wake cycles.
Does melatonin help you sleep? When taken as supplement, its function is to mimic the effects of the natural hormone. Drowsiness generally occurs within 30 minutes after taking a dose. Taking this medication right before bed may not be the best strategy for all sleep disorders. Ask your doctor about the best method of dosing. This medication does not work for everyone.
Is Melatonin a Hormone?
Melatonin is a natural hormone when produced in the body (the endogenous hormone). It is not a vitamin. Melatonin supplements (exogenous hormone) are made synthetically and all products and strengths on the U.S. market are available without a prescription at the pharmacy, nutrition stores, and other retail shops.
Before Taking This Medicine
Do not use melatonin if you are allergic to it.
Before using this medication, talk to your healthcare provider. You may not be able to use this medication if you have certain medical conditions, such as:
diabetes
depression
a bleeding or blood clotting disorder such as hemophilia
taking a blood thinner like warfarin
high or low blood pressure
epilepsy or other seizure disorder
if you are using any medicine to prevent organ transplant rejection
an autoimmune condition
using other sedatives or tranquilizers
It is not known whether this medication will harm an unborn baby. Do not use this product without medical advice if you are pregnant.
High doses of this medicine may affect ovulation, making it difficult for you to get pregnant.
It is not known whether melatonin passes into breast milk or if it could harm a nursing baby. Do not use this product without medical advice if you are breast-feeding a baby.
Do not give any herbal/health supplement to a child without medical advice.
