What Is Melatonin? Dosage, Side Effects, Sleep Usage, and Overdose Risk

Can’t sleep? You’re not alone. The number of Americans who regularly use melatonin as a sleep aid has quadrupled over the past 20 years, according to a study published July 27, 2022, in JAMA.

Quality sleep is definitely a cornerstone of good health, and melatonin, a hormone produced by our bodies, has long been thought of as a natural way to get through a restless night. Like all supplements, however, synthetic melatonin, which comes in pills, gummies, and other forms and is even marketed toward children, is not regulated by the U.S. Food and Drug Administration (FDA). Sleep experts are wary of the increasing reliance on melatonin supplements as a sleep aid, especially given the lack of rigorous research on the hormone’s long-term side effects.

Read on to learn what is known about melatonin supplements, how they work, potential side effects, and more.

Melatonin is a natural hormone produced by the pineal gland, according to the book Physiology of the Pineal Gland and Melatonin. This gland is located near the middle of the brain, and for the most part, remains relatively inactive — until you’re ready to sleep. Melatonin is a unique hormone because it’s released only in the dark, to prepare your body for sleep. Typically, melatonin levels increase in the bloodstream about two hours before bed, according to Johns Hopkins Medicine. This causes a sleepy feeling, resulting in a restful night.

Most people produce enough melatonin to fall asleep and stay asleep with no problem, according to Johns Hopkins Medicine. But some people don’t produce enough, and melatonin levels can change over time and for different reasons.

It is believed that melatonin levels decrease with age, even in otherwise healthy people, per the Mayo Clinic. In people with sleep disorders that affect their circadian rhythms and interfere with the timing of sleep (such as delayed sleep phase syndrome), melatonin production may play a role.

Some everyday habits can also affect melatonin production. Sleeping in less than complete darkness is one factor that contributes to sleep problems, says Carolyn Dean, ND, MD, the author of 365 Ways to Boost Your Brain Power: Tips, Exercise, Advice. Also, blue light emitted from your phone or TV too close to bedtime can interrupt your circadian rhythm and suppress your melatonin production, per the American Sleep Association (ASA).

It’s also important to make sure you get enough of what Dr. Dean calls “the sleep mineral,” magnesium. “Magnesium facilitates sleep-regulating melatonin production, and studies have shown that magnesium helps you get a deep and restful sleep,” she says. “Magnesium also relieves muscle tension that can prevent restful sleep.”

Some research supports these claims. Past research found that in a group of elderly adults with insomnia, those who took magnesium supplements showed a significant increase in melatonin levels compared with those who didn’t take a supplement. Other research has shown that magnesium blocks calcium (which makes muscles contract) to help muscles relax.

If your body doesn’t produce enough melatonin naturally, your doctor may recommend a supplement with synthetic melatonin.

Oral forms of synthetic melatonin include melatonin gummies, pills, liquids, chewables, and capsules. You can purchase the hormone in other forms, too, including melatonin sprays, powder, patches, and creams, all of which are available in grocery stores, pharmacies, and health food stores. Melatonin supplements are marketed to help with sleep and jet lag.

As pointed out by the JAMA study, many melatonin users regularly take doses higher than the maximum recommended 5 milligrams (mg) per night. This is particularly concerning in regard to children. A report published in June 2022 by the Centers for Disease Control and Prevention (CDC) examined data between the years 2012 and 2021 and found that poison control had fielded 260,435 calls about kids who had taken too much melatonin. Of those, two children under the age of 2 died, five were put on a ventilator, nearly 300 ended up in intensive care, and more than 4,000 were hospitalized.

Part of the problem may be that there is “no general consensus” regarding melatonin dosage, according to the aforementioned book. Recommended dosages vary by brand, and can range from 0.3 to 10 mg, per the The Sleep Doctor. Low doses (from 0.1 to 0.3 mg) may be used for circadian rhythm synchronization, while sleep disorders may require doses ranging from 0.6 to 5 mg.

It’s important to speak to a qualified healthcare provider about the correct dosage for yourself, or for a child who has sleep issues because of a developmental or neurological problem.

The melatonin your body produces is instrumental in helping you fall asleep. Melatonin supplements are often seen as a more natural way than prescription medications to help you drift off.

Although melatonin supplements are widely used for that purpose, they do not function the same way sleeping pills do. If you take a sleeping pill, you may fall asleep within 8 to 20 minutes of ingesting the medicine, reports the Cleveland Clinic. Melatonin supplements send a signal to the brain that it’s time to sleep, and your brain then signals your body to prepare for sleep (which usually takes up to 40 minutes, the Cleveland Clinic says.

Keep in mind that chronic issues with sleep might be caused by something other than an inability to produce melatonin naturally, such as poor sleep hygiene, caffeine and alcohol consumption, night-shift work, and recent travel.

Learn More About Melatonin Supplements and Sleep

Melatonin’s main use is as a natural remedy for helping reset a disrupted sleep schedule. But it's thought to be beneficial for issues other than sleeplessness. While more research is needed to understand the effects of the hormone, the supplement may help with the following conditions.

Cancer

A review published in May 2021 in Molecules found that melatonin had therapeutic anticancer effects against colorectal, breast, gastric, prostate, ovarian, lung, and oral cancers. It was found to mediate cell death, boost the immune system, and improve patient sleep and quality of life.

Alzheimer’s Disease

Alzheimer’s is characterized by the extracellular accumulation of amyloid-beta (Aβ) plaques and the formation of intracellular neurofibrillary tangles (NFT), and melatonin has been found to reduce both, along with reducing oxidative stress and neuroinflammation in both cell and animal studies, per review published in April 2022 in Frontiers in Neuroendocrinology. Additional research in humans is still needed.

Amyotrophic Lateral Sclerosis (ALS or Lou Gehrig’s disease)

A retrospective analysis published in January 2021 in Muscle & Nerve that looked at ALS patients in a large database found an association of slower ALS progression in those who took melatonin. The study authors stated that the results are merely preliminary, and further research is needed before any causal relationships can be inferred.

Nighttime High Blood Pressure

Past research found that repeated bedtime melatonin intake significantly reduced sleep blood pressure rates in males with untreated hypertension.

Irritable Bowel Syndrome

Research says melatonin is likely useful in mediating pain thresholds in those with IBS, but more studies are warranted.

Reproductive Issues

A study published in September 2019 in Antioxidants found that melatonin supplementation slightly enhanced in vitro fertilization success rates in women with unexplained infertility. The study was very small, however, with just 40 participants, and the study authors stated that “before a definite recommendation is made on the use of melatonin in women with [unresolved infertility], larger clinical studies in populations with different backgrounds need to be performed.”

COVID-19

The authors of a study published in April 2020 in International Reviews of Immunology reported that melatonin may reduce the severity of COVID-19, as it can inhibit programmed cell death, decrease inflammation in the lungs, and improve sleep and anxiety and therefore immunity. It’s also known to prevent fibrosis, one of COVID-19’s most dangerous complications.

Melatonin is a dietary supplement, and dietary supplements are not regulated or approved by the FDA. The FDA is, however, aware that dietary supplements can contain ingredients that conflict with a prescription medicine or a medical condition you may have, which is why they recommend consulting a doctor before taking one. According to MedlinePlus, melatonin may produce a moderate reaction when taken with birth control pills, some prescription drugs used for diabetes, high blood pressure, certain sedatives, and more. Consult your healthcare provider before taking melatonin if you are on any prescription medications.

Melatonin on its own can also cause side effects if you’re sensitive to the supplement. According to National Capital Poison Center, side effects vary, but include:

• Irritability
• Drowsiness
• Nausea
• Diarrhea
• Headache

Side effects don't always mean that you should stop taking melatonin. The decision to stop will depend on the severity of your side effects, and whether they improve or continue. If, for example, you take melatonin and repeatedly experience cramps or diarrhea the next day, you might be sensitive and want to consider other options for better sleep, perhaps chamomile tea or lavender oil, which has been shown to calm the nervous system.

To reduce the likelihood of side effects, it can help to start with a low dose of melatonin and increase your dose as needed. Consult your healthcare provider for information on exact dosages, and if you can, bring the specific supplement you will be taking because many brands of synthetic melatonin contain 5 to 10 mg per serving, which is more than what adults often need to regulate their sleep cycle.

“You should disclose all your medicines to your doctor or pharmacist prior to taking melatonin to assure there’s no potential interaction,” says Chrisoula Politis, MD, the director of sleep medicine at Mercy Medical Center in Rockville Centre, New York.

Learn More About the Potential Side Effects of Melatonin

Generally speaking, melatonin supplements are safe for most adults, although its use should be avoided in anyone who is pregnant or breastfeeding, says Dr. Politis. The effects of melatonin in those instances are understudied, and although the limited available research has found no adverse effects, per the Drugs and Lactation Database, further research is needed.

Melatonin can also cause an inflammatory response in the body in certain patients, so the Mayo Clinic recommends that people who have certain autoimmune diseases not take it. Some newer studies do not support this claim, however, so it's best to discuss it with your healthcare provider.

While it is generally agreed that melatonin supplements can be effective in the short-term, the National Center for Complementary and Integrative Health (NCCIH) says information on its long-term side effects and how long one can safely take it is lacking. Because of that lack of information and fears of long-term side effects, researchers behind the JAMA study recommend avoiding long-term sleep aid use before you try other approaches, like changing sleep hygiene, CBT for insomnia, and other stress management approaches.

If you have difficulty going to sleep or staying asleep and still want to try melatonin, one approach is to take melatonin for a couple of nights or weeks, and then stop taking the supplement for a few days to see if your sleep improves. If not, see your primary healthcare provider or a sleep specialist to rule out a disorder.

Melatonin is generally safe when used responsibly, but it is possible to overdose. The symptoms of an overdose can mimic those of common side effects, including moderate to severe diarrhea, tremors, low body temperature, or low blood pressure, according to the National Capital Poison Center.

Research has found that taking too much melatonin may also put you at risk for rebound insomnia, which is essentially the inability to sleep without it. So instead of melatonin helping to reset your sleep cycle, too much in your system may actually make your sleep problems worse. Too much melatonin can also lead to increased sleep inertia, which is that groggy transitional phase between waking up and actually feeling awake, per a review published in October 2017 in Sleep Medicine Reviews. In a perfect world, you should be able to take melatonin at night, sleep through the night, and wake up feeling refreshed. The opposite can happen if you overdose. Instead of waking up alert, you may have a hungover feeling.

Be mindful that sleep inertia can also occur if you take melatonin too late at night. If you take the supplement, allow for at least seven hours of sleep and don’t operate heavy machinery until you know how you’re affected, says Politis. If you take too much, medical attention isn’t always necessary. You’ll feel uncomfortable, but symptoms should gradually improve as the amount of melatonin in your bloodstream decreases, per the National Capital Poison Center.

The exception is if you have more severe symptoms, like low blood pressure. This is a dangerous complication of too much melatonin. See a doctor immediately to stabilize your health. Signs of low blood pressure include lack of concentration, blurry vision, and fainting, per the Mayo Clinic.

Learn More About the Risks of Overdosing on Melatonin

Melatonin can be helpful when you have trouble going to sleep or staying asleep in the short term. Better sleep hygiene, like dimming the lights at night and avoiding stimulating activities before bed, can help your body produce melatonin naturally.

If these measures don’t work, oral melatonin supplements or another form of the hormone might provide the restful sleep you need with minimal side effects. Just make sure to speak to your healthcare provider about how much to take and any potential side effects before you use it long-term.

Additional reporting by Kayla Blanton.