Is it possible to take too much melatonin? We asked the experts.

National Geographic

24-07-2025

Melatonin is a widely used supplement, touted for its sleep inducing effects. However, experts say the benefits only apply in certain situations—and as a result, it has been banned from being sold over the counter in various other countries including the United Kingdom, where it is only available as a prescription medication. Photograph by Rebecca Hale, National Geographic
If you've ever taken a melatonin supplement as a last-ditch attempt to save your sleep, you're in good company: Research suggests people in the U.S. have steadily reached for more melatonin over the past couple of decades, and an American Academy of Sleep Medicine (AASM) survey estimates that roughly two-thirds of U.S. adults have used some form of melatonin to help them drift off.
The appeal is undeniable: Your brain naturally makes this hormone to regulate your sleep-wake cycle. The synthetic form of melatonin usually found in supplements is a relatively low-risk substance for adults, plus it's available over the counter. Package this into a trendy bottle brimming with colorful gummies (with plenty of endorsements from 'wellness' influencers), and you're giving the chronically exhausted a glimmer of hope for better rest.
'People can become quite desperate,' says Jade Wu, a behavioral sleep medicine psychologist and the author of Hello Sleep. 'I don't blame them for trying whatever they can. And they're trying really hard to not abuse prescription medication.'
(​What's in melatonin—and is it giving you nightmares?)
When a low dose of those melatonin gummies doesn't actually stop them from tossing and turning, many of these sleep-deprived people are mainlining higher and higher doses.
But Wu, among other sleep experts, says melatonin is a widely misunderstood hormone. Taking it as a supplement night after night doesn't necessarily translate to better sleep—and for most people, neither does taking larger amounts of it. Which begs the question: Are we taking melatonin too often, and at too high of doses? Here's what the science says so far. How melatonin influences sleep
Your body relies on two systems to help you sleep, says Joshua Tal, a clinical psychologist specializing in sleep therapy in New York City. The first is your homeostatic sleep drive, or sleep pressure, a physiological process that kicks in after you wake up. As the day progresses, it drives your need for sleep, a bit like hunger drives your need for food, Tal explains.
Melatonin influences the second system: the circadian rhythm, or your body's internal clock. The average adult needs about eight hours of sleep each day; your circadian rhythm organizes when you achieve this rest.
(​Are you a 'lark' or an 'owl'? Your body clock holds the answer.)
'While the homeostatic drive promotes how much sleep we need, the circadian rhythm optimizes our ability to achieve that sleep at nighttime,' says sleep medicine specialist David Nelson Neubauer, an associate professor of psychiatry and behavioral sciences at Johns Hopkins Bayview Medical Center.
As you get closer to your typical bedtime, a small part of your brain—the suprachiasmatic nucleus, or 'the master timekeeper,' per Neubauer—regulates the release of melatonin into your bloodstream via your pineal gland. This suppresses your alertness, which indirectly helps you doze off because your body is being told it's time to be less active. Your melatonin levels stay high throughout the night, and then start to subside in the early morning hours. What we often misunderstand about melatonin
Prescription sleep medications, including benzodiazepines like Valium and 'Z' drugs like Ambien, are sedatives; they have a deeply tranquilizing effect. They're easy to misuse and notoriously habit-forming when taken long-term.
(Your brain 'washes' itself at night. Sleep aids may get in the way.)
By contrast, a melatonin supplement may facilitate the processes that help you fall asleep, but it won't make you stay asleep. 'A lot of people think of melatonin as a kind of sleeping pill, but it is not sedating,' Neubauer says. 'It is more of a signal to your circadian rhythm.'
Taking melatonin can work 'phenomenally well' if you have to get to bed at odd hours—say, if you're a night shift worker trying to sleep during the day or a traveler suffering from jet lag, says James K. Wyatt, director of the Section of Sleep Disorders and Sleep-Wake Research at Rush University Medical Center in Chicago. It can also be effective for people with a circadian rhythm disorder or delayed sleep phase who have trouble falling asleep early enough to wake up during typical morning hours.
Otherwise, for the average person, Wyatt says a melatonin supplement probably won't do much to improve sleep. While studies have yielded mixed results, Tal notes their findings suggest melatonin likely works no better than a placebo for insomnia (when you have trouble falling asleep, staying asleep, or both). Both the AASM and the American College of Physicians also maintain there's not enough evidence to recommend melatonin supplements as a safe or initial treatment for insomnia. Can you take 'too much' melatonin?
Much of the data scientists have on melatonin is based on a low dose of around 0.3 to 1 milligram, which is close to what our bodies naturally produce. The average supplement claims to offer between 3 to 5 milligrams, which may seem high at first.
'Nearly every drug has a 'dose response curve.' The bigger the dose, the bigger the effect,' Wyatt explains. But melatonin's curve is pretty flat because it doesn't work like a typical sleep medication in the body. Taking 3 milligrams versus 0.3 milligrams of melatonin, for instance, is 'mostly irrelevant from a clinical point of view,' Neubauer notes. So taking a higher dose likely won't make a difference in helping you fall asleep. (Some exceptions: Studies suggest higher doses may be beneficial for children with autism and folks with Parkinson's disease.)
(More parents are using sleep aids for their kids. Experts say they shouldn't.)
Yet supplements can pack a lot more—or less—melatonin than their bottles claim. One 2023 analysis found that, of 25 melatonin gummies on the market, a majority were stuffed with much more melatonin than what was listed on the label. One brand claimed to offer 3 mg per serving, but actually contained 10 mg; another melatonin/CBD hybrid contained no melatonin at all but exceeded its proposed level of CBD.
A slightly larger dose of melatonin (think: a serving size difference in the single digits) likely won't be harmful for most adults, but people also tend to have a more-is-more mentality with supplements, Wu notes. All the sleep experts interviewed for this article say they've had patients who came to them after taking high doses of melatonin, sometimes upwards of 30 mg a night, which can up the risk of unpleasant side effects like headaches, grogginess, nausea, dizziness, and vivid dreams or nightmares—not exactly soothing.
As for whether it's possible to 'overdose' on melatonin? There's no scientific consensus on what that exact amount would be for adults. Taking a high dose like 30 mg and up probably won't make you feel great, but it's very rarely life-threatening. (The story is different for children, who can end up in the hospital due to more serious toxicity risks.)
Given a lack of longitudinal data, we also don't know whether there are negative long-term effects of taking melatonin, Wyatt says. Ideally, scientists would regularly give the same group of study participants melatonin or a placebo, follow them over decades, and document the effects. But funding this research is expensive and tough to pull off even for strictly regulated prescription medications, let alone a supplement, he notes. What to keep in mind if you're melatonin-curious
It's never a bad idea to support your body's natural production of melatonin, Neubauer says. To do that without supplements, opt for dim and warm lighting at nighttime, avoid screens before bed if they're overstimulating to you, and do your best to get a dose of natural sunlight shortly after you wake up, as well as throughout the day.
(Light pollution is harming our health.)
If taking a supplement makes sense for your situation because you travel a lot or work the night shift, know that the U.S. Food and Drug Administration doesn't regulate melatonin in the same way it rigorously regulates drugs, which opens the door for flashy marketing claims that aren't scientifically up to snuff, according to Pieter Cohen, an associate professor of medicine who researches the safety of supplements at Harvard Medical School. That's why he recommends looking for a product that's been independently tested by a third-party lab, like USP or NSF.
The good news is, melatonin supplements don't pose the same risk for physical dependency like sleep medications do, Tal says. So you could try melatonin without experiencing physical withdrawal symptoms or rebound insomnia when you stop taking it.
But there's a flipside to be aware of: Experts agree that you can become psychologically dependent on having a gummy each night (or doing any pre-sleep ritual, for that matter). Many sleep problems are rooted in anxiety about falling and staying asleep, Tal explains. So when you take something that promises to ease that process—whether it be melatonin or another 'natural' sleep aid—you give yourself the mental greenlight to relax and doze off, creating a positive association between that behavior and snoozing away.
This powerful placebo effect is not necessarily harmful unless it's potentially masking a bigger problem. If you have undiagnosed sleep apnea, for example, you could be delaying a more effective treatment plan if you head for the supplement aisle before your doctor's office, Neubauer says. The same goes for insomnia: The gold-standard treatment is cognitive behavioral therapy for insomnia, not medication or supplements, Wyatt notes.
'Melatonin is not a panacea for all sleep problems, and it could even backfire depending on what your actual sleep problem is,' Wu says. 'So let's slow down from the quick fixes and figure out what the issue is in the first place. That's where a sleep professional can be really helpful.'