Americans are exhausted—and desperate for solutions. Eighty percent of adults in the U.S. struggle with sleep at least once a week, according to a recent nationally representative Consumer Reports survey of 1,767 adults.

And many of those in search of better sleep turn to dietary supplements. Twenty percent of adults in the U.S. said they had tried a natural remedy for their sleep woes within the past 12 months, about as many as those who turned to over-the-counter drugs. And given the side effects and limited effectiveness of sleep drugs, it’s easy to understand why supplements are so popular.

More on Sleep

The most popular of the bunch, by far, is melatonin, a hormone naturally produced by the body that governs our sleep-wake cycle. Eighty-six percent of people who said they had tried a dietary supplement for sleep identified melatonin as their remedy of choice.

All that interest translates into big bucks: Americans spent approximately $408 million on melatonin in 2017, according to the Nutrition Business Journal.

Is that money well spent?

About a quarter of Americans who tried a supplement say they got very good or excellent sleep, according to CR’s survey.

But scientific research is mixed, says Charles Czeisler, Ph.D., M.D., chief of the division of sleep and circadian disorders at Brigham and Women’s Hospital in Boston. “Melatonin has important but limited uses,” he says.

Melatonin is a hormone secreted by the brain’s pineal gland, usually at night. It regulates the body’s circadian rhythm, the approximately 24-hour internal “clock” that helps control when you’re sleepy and when you feel awake.

It’s the “hormone of darkness,” Czeisler says, something that the brain should start to release as it gets dark, a few hours before we usually go to sleep.

Taking a synthetic supplemental form of that hormone might help people who aren’t producing the hormone naturally because of age, one of several health disorders, or because they’re trying to go to bed at a different time than usual. But it’s less likely to help in most other circumstances and could cause side effects like next-day drowsiness.

Here’s what to know about melatonin, including when it might help and how to use it safely.

When Melatonin Can and Can't Help

Some people with certain kinds of sleep disorders may get some relief from melatonin, research suggests, but there’s less evidence for its use with more common forms of insomnia, according to the NIH’s National Center for Complementary and Integrative Health.

A 2013 meta-analysis found that on average, people with insomnia fell asleep about 7 minutes faster with melatonin than with a placebo. While most melatonin side effects are mild, CR’s survey showed that people may be taking it in unsafe ways, for example, driving too soon after taking it or taking it long term (for years) when there’s little data indicating that longer than three months is safe.

Because of the lack of evidence, the American Academy of Sleep Medicine recommends clinicians not use melatonin as a treatment for insomnia.

But that doesn’t mean it can’t help anyone.

Around 5 to 10 percent of people may feel sleepy after taking melatonin, says Alcibiades Rodriguez, M.D., the medical director of the Comprehensive Epilepsy Center-Sleep Center at New York University.

“Usually the people that get more benefit are the elderly, maybe 70 or older, and young patients,” he says. That’s because older patients and young children are less likely to produce sufficient melatonin on their own, though it’s important to consult a medical professional before giving a child melatonin. There’s still little research on melatonin in kids and some concern about how melatonin might affect development, especially around puberty

Because the general cue for the body to start releasing melatonin is the change from daylight to darkness, supplements may be essential for people with circadian disorders related to blindness, Czeisler says. It can also help people who need to fall asleep at a time that’s not in sync with their natural clock, like people working a night shift or anyone experiencing jet lag because they have traveled to a new time zone.

Czeisler says melatonin may help some extreme night owls—people whose internal clock makes them inclined to fall asleep hours later than would be considered reasonable—by helping to get their body clocks on a more normal schedule.

What to Know Before You Take Melatonin

  • Start small and don’t overdo it. Many stores sell supplements that are packed with far more melatonin than the body naturally produces. Czeisler recommends starting with a low dose, between 0.2 and 0.5 mg. The Council for Responsible Nutrition (CRN), a supplement trade group, says doses should not exceed 10 mg, even though products with higher doses are available.
  • Get it from a safe source. Supplements aren’t subject to the same standards set by the Food and Drug Administration for safety and efficacy as are over-the-counter and prescription drugs. That means supplement makers don’t have to show that their products work. Certain supplements may contain a higher or lower dose or may have other potentially dangerous ingredients. Labels from the supplement-verifying organizations ConsumerLab.com, NSF International, USP, and UL can provide some assurance that a product contains what's listed on its label and that the product isn’t contaminated with something risky.
  • Make sure it won’t interact dangerously with other drugs you take. Melatonin can change the way other drugs work, making blood pressure and diabetes drugs less effective and increasing the effects of blood-thinning drugs, for example. Talk to your doctor before taking melatonin if you use any medication.
  • Be careful driving the next morning. Short-term use of melatonin is generally considered safe, Rodriguez says. But some people do report drowsiness, headaches, dizziness, or nausea. The Council for Responsible Nutrition says not to drive while using melatonin. In our survey, we found that 24 percent of supplement users experienced drowsiness or fogginess the day after taking it, and 22 percent had driven within 7 hours of taking a supplement for sleep.
  • Be cautious about long-term use. Studies have shown that melatonin appears to be safe when used for three months or less, according to reviews of research and the NIH. But a lack of long-term studies means we don’t know if long-term use is safe. Over one-third of respondents in our survey said they’d been taking a supplement for sleep for a year or longer.
  • Talk to a doctor about sleep problems. Whether melatonin helps you, you should consult your doctor if you’ve had trouble sleeping for three months or longer, according to Rodriguez. “The longer insomnia goes, the more difficult it is to treat,” he says.

Editor's Note: This article has been updated since a version first appeared in the February 2016 issue of Consumer Reports magazine.