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Melatonin, best known for its use as a sleep aid, is one of the top five most widely consumed supplements in the United States, according to the National Institutes of Health’s Health Interview Survey (NHIS). And it’s no surprise, considering almost 40% of Americans report having problems falling asleep, according to 2013 research in PloS ONE.
Since its discovery in the late 1950s, melatonin has evolved into a well-known natural sleep remedy. But once you dig into the facts, you might be surprised by what melatonin really is and what researchers say it can do for your body.
Melatonin Facts
Melatonin is a hormone produced in the body by the pineal gland, a tiny gland found deep in the brain. The pineal secretes melatonin in response to reduced light. Endogenous melatonin—melatonin found naturally in the body—is supposed to help make you increasingly sleepy as the evening sets in and bedtime approaches.
Melatonin supplements (called exogenous melatonin) are generally synthetically produced hormones. They’re available over the counter in the U.S., though you need a prescription in many other countries to obtain them.
Melatonin is commonly used as a sleep remedy, but people often misunderstand it, says Michael Grandner, M.D., director of the sleep and health research program at the University of Arizona College of Medicine in Tucson.
“Melatonin doesn’t work like a prescription sleeping pill. It’s much more nuanced,” he says. “Melatonin may help someone fall asleep a bit faster and it may help them stay asleep during the night, but a lot of supplement manufacturers overpromise.”
Grandner says melatonin supplements may improve the ability to fall asleep faster for some people, but how much will be slight, measured in minutes—not hours. Melatonin supplements are best for someone with mild sleep issues, he says.
Indeed, the American Academy of Sleep Medicine says that melatonin may be used for some problems related to sleep timing, but it’s not a solution for a serious sleep issue like chronic insomnia.
Melatonin Dosage
Grander advocates for low doses of melatonin to trick the body into believing the supplement is a natural signal—meaning the body mistakes the supplement for your body’s own natural production of melatonin. If you flood the body with an extremely high level of melatonin, he warns, there’s a chance your body will simply override it, treating it like an error signal.
For this reason, he suggests patients try taking half a milligram of melatonin about one to two hours before they would normally go to bed. You may have to experiment with timing and a higher dose, though. Here’s a sample of what the research says:
For adults who who have trouble falling asleep at a conventional bedtime (delayed sleep phase syndrome): A 2010 review in Sleep found studies that administered 0.3 milligrams to 5 milligrams of melatonin nightly with participants concluded that melatonin made a positive impact on total sleep time and sleep onset.
For adults who have sleep problems caused by beta blockers (high blood pressure medication): A 2012 study in Sleep found that 2.5-milligram capsules of melatonin taken one hour before bedtime each night increased participants’ total sleep time by 36 minutes and decreased the time it took them to fall asleep by eight minutes.
For adults 65 and older with sleep disturbances: Natural melatonin production can wane with age, leading to more sleep issues as you get older. A 2019 review that only included studies of adults at least 65 years old concluded that those participants benefited from using between 1 milligram and 6 milligrams of melatonin a night.
Children on the autism spectrum (ages 2 to 18) with delayed sleep: One study in the Journal of Pineal Research gave children with autism 5 milligrams of controlled-release (or time-release) melatonin each night. The researchers concluded the supplements improved the sleep of 47 out of 51 children enrolled in the study and produced an average total sleep time improvement of 30 minutes.
Can You Overdose on Melatonin?
It’s unlikely that you’ll suffer any serious side effects if you take a large dose of melatonin, but you may not feel so great, either, says Grandner. You could experience nausea or a headache. However, it won’t last long—melatonin only stays in the body for about five hours.
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Melatonin Side Effects
Some users report headaches, an upset stomach or daytime grogginess after taking melatonin. The American Academy of Sleep Medicine discourages people with dementia from taking melatonin because it might increase their risk of falls or increase feelings of disorientation at night. It’s also known to stay active in older people longer, which may cause daytime drowsiness.
But, overall, melatonin used as a sleep aid in the short term (less than six months) is considered safe. Since most studies, especially those looking at sleep and melatonin, only last three to four weeks, more research is needed on the possible long-term impacts of melatonin supplementation.
There are other considerations to keep in mind as well. Researchers are discovering melatonin plays a role in many components of health beyond sleep, including anxiety, migraines, heart function, immune responses, digestion, depression, fertility and more.
For instance, a 2013 study in the Journal of Andrology concluded that melatonin may negatively impact men’s semen quality. And Florida State University researcher James Olcese says melatonin may impact female fertility, too. If you’re trying to get pregnant, currently pregnant or breastfeeding, talk to your doctor before taking a melatonin supplement.
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Mixing Melatonin With Other Medications
Melatonin has a variety of effects when mixed with prescription medications. For example, research in the Journal of Cardiovascular Disease Research found melatonin might be beneficial for people taking beta blockers because these high blood pressure medications reduce the body’s natural production of melatonin. But people taking the blood thinner warfarin may want to avoid melatonin because it can interfere with blood clotting, according to a 2016 study in Life Sciences Journal.
Some research has also found possible benefits of adding melatonin to treatments that involve selective serotonin reuptake inhibitors (SSRIs) for depression and bipolar disorder. Melatonin may interact with immunosuppressants and epilepsy medications as well.
Bottom line: Anyone taking prescription medication should consult their doctor before adding a melatonin supplement to their daily regimen, says Grandner.
How to Choose a Melatonin Supplement
There’s a lot to be desired when it comes to supplement reliability, suggests research in Clinical Sleep Medicine. For instance, it found melatonin content in supplements ranged from 83% less to 478% more than the concentration declared on the product label. It also found shocking lot-to-lot variability—melatonin levels varied by as much as 465% when comparing different batches of the same product from the same manufacturer.
Grandner says there isn’t much a consumer can do except buy from a brand with a good reputation. “Look for the bigger and more established companies,” he says. “They have more to lose if they sell inferior products.”
Sources
Nationwide study reports shifts in Americans’ use of natural products. National Institutes of Health. Accessed 6/3/2021.
Melatonin: What You Need to Know. National Institutes of Health’s Center for Complementary and Integrative Medicine. Accessed 6/3/2021.
Ferracioli-Oda E, Qawasmi A, Bloch M. Meta-Analysis: Melatonin for the Treatment of Primary Sleep Disorders. PLoS ONE. 2013;8(5).
Attenburrow MEJ, Cowen PJ, Sharpley AL. Low dose melatonin improves sleep in healthy middle-aged subjects. Psychopharmacology. 1996;126:179-81.
Geijlswijk I, Korzilius H, Smits M. The Use of Exogenous Melatonin in Delayed Sleep Phase Disorder: A Meta-Analysis. Sleep. 2010;33(12):1605-1614.
Scheer F, Morris C, Garcia J, et al. Repeated Melatonin Supplementation Improves Sleep in Hypertensive Patients Treated with Beta-Blockers: A Randomized Controlled Trial.Sleep. 2012;35(10):1395-1402.
Brzezinski A, Vangel M, Wurtman R, et al. Effects of exogenous melatonin on sleep: a meta-analysis. Sleep Medicine Reviews. 2005;9(1):41-50.
Sack R, et al. Sleep-Promoting Effects of Melatonin: At What Dose, in Whom, Under What Conditions, and by What Mechanisms? Sleep. 1997;20(10):908-915.
Wasdell MB, Jan JE, Bomben MM, et al. A randomized, placebo-controlled trial of controlled release melatonin treatment of delayed sleep phase syndrome and impaired sleep maintenance in children with neurodevelopmental disabilities. Journal of Pineal Research. 2008;44:57-64.
Dolberg O, Hirschmann S. Grunhaus L. Melatonin for the Treatment of Sleep Disturbances in Major Depressive Disorder. The American Journal of Psychiatry. 1998;151(8):119-1121/.
Härtter S, Grözinger M, Weigmann H, Röschke J, Hiemke C. Increased bioavailability of oral melatonin after fluvoxamine coadministration. Clinical Pharmacology & Therapeutics. 2000;67:1-6.
Olcese J. Melatonin and Female Reproduction: An Expanding Universe. Frontiers in Endocrinology. 2020;11:85.
Luboshitzky R, Shen-Orr Z, Nave R, Lavi S, Lavie P. Melatonin Administration Alters Semen Quality in Healthy Men. Journal of Andrology. 2002;23:572-578.
Ashy N, Schroff K. Evaluation of the Potential Drug Interaction of Melatonin and Warfarin: A Case Series. Life Science Journal. 2016;13(6).
Buscemi N, Vandermeer B, Pandya R, et al. Melatonin for Treatment of Sleep Disorders: Summary. AHRQ Evidence Report Summaries. 2004;108.
Besag FMC., Vasey MJ, Lao KSJ, et al. Adverse Events Associated with Melatonin for the Treatment of Primary or Secondary Sleep Disorders: A Systematic Review. CNS Drugs. 2019;33:1167-1186.
