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Melatonin for Sleep: Does It Work, and Is It Safe?

The popular supplement comes with side effects and questions about its effectiveness

spinner image a woman taking melatonin capsules with a glass of water in her bedroom at night
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A good night’s sleep is about more than beauty rest. Research has linked quality sleep to better brain health, heart health and mental health — it can even lower risks for certain cancers. 

But a new study suggests that an increasing number of Americans are having trouble getting those all-important z’s. Researchers tracked a fivefold increase in melatonin use among U.S. adults in the past few decades. Published in February in JAMA, the study also found that people are taking higher doses of the over-the-counter supplement than what’s typically recommended — despite scant evidence that melatonin works for your run-of-the-mill shut-eye issues, including insomnia.

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“We know that melatonin is often used as a sleep aid, but it’s actually misused as a sleep aid because it’s not a sleep aid,” says Naima Covassin, a coauthor of the study and a sleep disorder expert at Mayo Clinic.

Popping a melatonin pill or gummy before bedtime may help you fall asleep a few minutes faster, Covassin says, but it won’t make much of a difference in the number of times you’re waking up at night or how many total hours you’re getting. “There's actually very little improvement in all of these parameters,” she adds.

When does melatonin work?

To understand when melatonin can be beneficial, it’s important to know more about its role in the sleep-wake cycle.

Many consumers are familiar with the bottled version of melatonin — around 6 million U.S. adults reach for it. But melatonin is a naturally occurring hormone the brain produces in response to darkness to help our bodies know when it’s time to go to sleep and when it’s time to be awake.

Side effects of melatonin

Short-term use of melatonin may cause mild side effects, including:

  • Headaches
  • Dizziness
  • Nausea
  • Drowsiness

Less common side effects include:

  • Short-term feelings of depression
  • Mild tremor
  • Mild anxiety
  • Abdominal cramps
  • Irritability
  • Reduced alertness
  • Confusion or disorientation

Source: Mayo Clinic

When melatonin hits the bloodstream (typically a few hours before bedtime), it reduces alertness and “facilitates our ability to fall asleep,” explains David Neubauer, M.D., associate professor of psychiatry and behavioral sciences at Johns Hopkins Medicine. It also helps cool off the brain and the body, “which helps you sleep better,” says James K. Wyatt, director of the Section of Sleep Disorders and Sleep-Wake Research at Rush University in Chicago.  

Because melatonin doesn’t have the same sedating effect that many sleep aids provide, taking it in pill form is less helpful on those nights when you can’t seem to fall asleep or stay asleep.

It can work, however, in instances when you want to adjust your biological sleep clock — say, to overcome jet lag after traveling through several time zones or to shift your schedule entirely so that you’re going to bed a few hours earlier. 

Melatonin supplements can also benefit shift workers who need to sleep during the day, when the body’s melatonin levels are naturally low. That’s when supplementing with melatonin is “actually quite effective,” Covassin says. 


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And in older adults, it may be able to prolong sleep when taken for an extended period of time, though more research is needed. A small study from researchers at Brigham and Women’s Hospital in Boston found that when adults ages 55 to 78 took 5 milligrams of melatonin for two weeks, they increased their sleep time by at least 15 minutes, compared to those who took a placebo. 

Is melatonin safe?

Melatonin is generally safe and well-tolerated. But just because it’s available in the U.S. without a prescription and sold alongside multivitamins and probiotics doesn’t mean it’s risk-free. (In many countries it can be purchased only by prescription.)

“We think since it’s available over the counter that it’s harmless, but it may not necessarily be true,” Covassin says. Short-term use of melatonin supplements can come with a list of side effects, especially when taken in high doses, including headaches, dizziness, nausea, fatigue and daytime sleepiness. Vivid dreams and nightmares have also been reported. “These are mild, but they can also affect your daytime function; think about if you have to drive or if you have to operate machinery,” Covassin points out. 

Further, the National Center for Complementary and Integrative Health (NCCIH) at the National Institutes of Health says that melatonin may stay active in older adults longer, which could lead to daytime drowsiness. The research center also notes that information on long-term safety is lacking.

More serious, albeit rare, reactions have been linked to melatonin supplements, including changes in heart rate and blood pressure, temporary feelings of depression, seizures, and confusion or disorientation. What’s more, melatonin has been shown to affect glucose tolerance, or the body’s ability to handle sugar.

There are drug interactions to consider, too. For example, melatonin can increase bleeding risks among people taking anticoagulants and antiplatelet drugs; it can worsen blood pressure in those taking blood pressure medications, and it can stimulate immune function and interfere with immunosuppressive therapy, according to Mayo Clinic.

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“So, obviously, this should be taken with caution,” Covassin says. “And that’s my main recommendation. If you are thinking [about taking melatonin] or if you are already taking melatonin, talk with your provider to determine whether it's actually appropriate for you.”

It’s important to know that, as with all dietary supplements in the U.S., federal regulations are less strict for melatonin than they are for over-the-counter medicines and prescription drugs. A 2017 study published in the Journal of Clinical Sleep Medicine found that the contents of the majority of melatonin products didn’t match what was listed on the label — their concentrations ranged, and so did the presence of other ingredients. Adding to the evidence, a more recent study published April 25, 2023, in JAMA looked at melatonin quantities in 25 sleep gummy products, often marketed to children, and found that 22 of them contained different amounts of melatonin than what was declared on the label. The actual quantity of melatonin ranged from 74 percent to 347 percent of the labeled amount; only three products had melatonin levels within 10 percent of the declared quantity.

The American Academy of Sleep Medicine offers a tip: When comparing supplement labels, look for the “USP Verified” mark, which indicates that the formulation meets the requirements of the U.S. Pharmacopeial Convention.

What can you do if you have trouble sleeping?

5 Tips for getting a better night’s sleep  

  1. Be consistent: Go to bed at the same time each night, even on weekends.
  2. Make sure your bedroom is quiet, dark, relaxing and at a comfortable temperature.
  3. Remove electronic devices from the bedroom.
  4. Avoid large meals, caffeine and alcohol before bedtime.
  5. Get some exercise: Being active during the day can help you fall asleep at night.


Source: Centers for Disease Control and Prevention 

Interested in making some adjustments to your sleep schedule? Before you reach for a pill, Neubauer recommends trying to maximize the melatonin your body produces naturally. You can do this by getting outside and staying active during the day. “Just getting light makes your circadian rhythm more robust, and the more active you are in the daytime, the better chance you have of sleeping more at nighttime,” he says. And because light suppresses the production of melatonin, keep levels low at night — this means limiting the use of your phone, tablet, computer and TV an hour or two before bed.

If you’re having trouble sleeping more generally, it’s important to talk with a doctor to figure out the cause, Wyatt says. “It’s rare when sleep goes bad just on its own and it's not because of other things, like the side effects of a different medication, or stress or anxiety or depression, or a pain disorder that’s insufficiently treated — there are all sorts of things.”

A third of U.S. adults report that they usually get less than the recommended amount of sleep (seven or more hours per night for adults), according to the Centers for Disease Control and Prevention, and the COVID-19 pandemic has only worsened slumber problems, research shows. The good news: There are treatments for insomnia, and a successful one, cognitive behavioral therapy, doesn’t come in pill form.

“We’re starting to realize treating insomnia is not just about getting a better night’s sleep,” Wyatt says. “It’s to significantly reduce risk for some of these negative health outcomes that could come years to decades later.”

Melatonin and children 

Melatonin use isn’t just increasing among adults — more children are taking it as well.

In fact, the number of pediatric melatonin ingestions increased 530 percent between 2012 and 2021, with the largest yearly increase (about 38 percent) occurring from 2019 to 2020, a new report from the Centers for Disease Control and Prevention (CDC) finds. In 2020, the supplement became the most frequently ingested substance among children reported to national poison control centers — some of these cases required hospitalization. 

The authors of the CDC report point out that melatonin has become widely available in the U.S. — some children’s varieties are even sold in “gummy” form. Still, it’s considered a dietary supplement and is subject to less regulatory oversight than other over-the-counter (OTC) medications. 

“Increasing use of OTC melatonin in various formulations, lack of robust manufacturing regulations, and varied dosing recommendations can place children at risk for potential adverse events,” the authors write. They go on to call for more research into the causes of increased melatonin ingestions among children and for public health initiatives to raise awareness. “Child-resistant packaging for this supplement should be considered, and health care providers should warn parents about potential toxic consequences of melatonin exposure,” they add.​​​​​​​​

Editor's note: This article, originally published June 6, 2022, has been updated to reflect new information.

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