A handful of melatonin pills

How Much Is Too Much Melatonin? Here’s What Experts Say.

Melatonin is natural, but taking too much of the supplement may lead to adverse side effects. Here’s how to find the sweet spot.

Fast Facts

  • More people are taking melatonin—and taking higher doses of the supplement—than in the past. But how much melatonin is too much? The answer may surprise you.
  • Melatonin may help your body prepare for sleep, but it is important to speak with a health care provider if you’re having trouble sleeping for more than a month. 
  • Researchers are still looking at the safety of long-term melatonin use. Some studies suggest that long-term melatonin use may affect reproductive hormones.

For many people, getting good sleep was a challenge before Covid. Then the pandemic arrived, upending routines and ushering in new waves of anxiety, stress, even grief—and more reasons to keep us up at night. A review found that around 40% of adults (1) experienced sleep problems during the early months of the pandemic, giving rise to the term “coronasomnia” to describe our sleep struggles. Because those hours of being wide awake in the darkness aren’t always pleasant, more people have turned to melatonin to get more rest. But that might leave you wondering: Is it safe to take the supplement nightly? And how much melatonin is too much?

More People Are Using Melatonin For Sleep

Our collective use of the supplement has been steadily growing for the past two decades, according to a recent study (2) published in the Journal of the American Medical Association.

And not only are more of us taking melatonin, we’re taking more of it. According to the study, since 2006, the number of people using more than 5 mg per day—typically the maximum recommended dosage—has risen. By 2018 people were taking more than twice the amount they did 10 years earlier. And that is raising a lot of safety red flags. 

Though melatonin is considered safe for most people, here’s what sleep specialists want you to know before popping this popular sleep aid.

Could Low T Be Messing With Your Sleep?

Poor sleep is a symptom of low testosterone. Test your T levels today.

Melatonin Is A Hormone, Not A Sleeping Pill

Melatonin is a hormone that’s naturally produced, mainly by the brain’s pineal gland, to help regulate your 24-hour sleep wake cycle. 

“Levels rise in the evening, prompting physiological changes like lowered body temperature and respiration rate, signaling the body to prepare for sleep,” says Jenna Gress Smith, Ph.D., founder of Arizona Sleep & Health in Phoenix, AZ, and sleep scientist at Crescent Health. “Over-the-counter supplements are thought to work in a similar way, helping the systems in your body align in the evening in preparation for rest. By supplementing, you’re adding to that signal to help put your body in a quieter state.”

Melatonin doesn’t work like prescription sleeping pills, Gress Smith says. “It’s not sedating, so it won’t override or silence the parts of the brain that keep your mind buzzing, or treat any other factors that can cause insomnia, such as stress or a mental health disorder.”

And unlike prescription sleep aids, you need to take a dose an hour or two before bed to see any effect (many people take it right before bed or in the middle of the night, expecting it to knock them out. It won’t.)

Related: Here’s Exactly How Much Deep Sleep You Need, According To Sleep Experts

How Effective Is Melatonin?

Melatonin can be very effective—in the right situations. The supplement works best when your internal clock has been thrown out of whack. “Melatonin tends to be more effective in elderly individuals, for jet lag, shift work, or for those with circadian rhythm disorders where it’s recommended by a sleep medicine physician,” says Gress Smith.

When it comes to folks just looking to lengthen their nightly rest, studies report underwhelming results.

“Reviews that have looked across studies (3) found that melatonin increased sleep efficiency by about 2 percent.” Translation: You may fall asleep about 4 minutes faster, and sleep around 13 minutes longer—not a lot to write home about.

Related: How to Fall Asleep in 10 Seconds

How Much Melatonin Is Too Much?

If you’ve ever shopped for melatonin, you may have found that many of the brands lining pharmacy shelves tend to start at 3 mg and are readily available in doses up to 10 mg. “Ten milligrams is much more than your body needs, plus those larger amounts haven’t been studied,” says Gress Smith. 

Though there are no standardized dosages for adults, many sleep experts suggest starting with a low dose of .1 to 5 mg and seeing how your body responds.

A word of warning: The U.S. Food and Drug Administration (FDA) does not regulate dietary supplements as drugs, which includes melatonin. So there are no standardized drug quality controls around the safety, quality, or accuracy of listed ingredients. According to a 2017 study, the actual content of melatonin in marketed supplements ranged from 83% up to 478% higher (4) than the label indicated. Which means you can inadvertently end up taking an inappropriate, possibly dangerous, amount. 

Can You Overdose On Melatonin?

There have been no reported deaths from taking too much of the sleep aid, and most people won’t have any life-threatening complications if they take too much, says Gress Smith. But you can experience some unpleasant side effects, including headaches, dizziness, nausea, or daytime drowsiness. Less common are mild anxiety, stomach cramps, disorientation, and short-term depression.

What Are The Long-term Effects Of Taking Melatonin?

Currently there’s not enough information to fully determine the safety of long-term use. Some of the concern around taking the supplement for extended periods has centered around its potential to affect reproductive hormones in both men (5) and women (6) though studies have returned conflicting results. 

While the exact mechanism of action is still unclear, “melatonin and reproductive hormones do interact,” says Gress Smith. In one study, long-term melatonin use was associated with decreased semen quality (7), while another study (8) seemed to suggest the opposite.

Although melatonin isn’t addictive like some prescription sleep aids, some experts say it can create a psychological dependence. Most agree that it’s not meant as a long-term solution to sleep problems despite the fact that plenty of people have been using it that way.

Too much melatonin can cause side effects like headaches, dizziness, nausea, and drowsiness.

When Should I Talk With a Doctor About Sleep Problems?

There are many different reasons people experience sleep disorders, and “there’s no one-size-fits-all cure for all of them,” says Gress-Smith. 

“Medical conditions such as anxiety or other mood disorders, sleep apnea, and asthma can disrupt sleep, and so can certain medications, or lifestyle choices like alcohol consumption.” 

“If you’ve been having trouble sleeping for a month or more it’s a good idea to speak with your doctor to rule out any underlying health issues that require medical intervention or treatment.” Be sure to mention if you’re taking any prescription medications such as blood thinners, blood pressure medication, anti-seizure or diabetes medications, immunosuppressants, or medication to treat obsessive-compulsive disorder, since melatonin can interact with these drugs.

Alcohol interferes with the effectiveness and potency of many medications and supplements, and melatonin is no exception. That evening cocktail or nightcap can either weaken or strengthen its effects.

Many people assume that because melatonin is “natural” that means it’s risk-free, says Gress Smith. “Hormones, even in small amounts, can affect your body in powerful ways, and we’re still learning about what those risks may or may not be.

The Bottom Line

    Studies are still being done on the safety of long-term melatonin use. Some research suggests that long-term melatonin use may affect reproductive hormones.Taking too much melatonin can cause unpleasant side effects. If you’re struggling with sleep for more than a month, see your doctor.
1. Jahrami H, BaHammam AS, Bragazzi NL, Saif Z, Faris M, Vitiello MV. Sleep problems during the COVID-19 pandemic by population: a systematic review and meta-analysis. J Clin Sleep Med. 2021 Feb 1;17(2):299-313. doi: 10.5664/jcsm.8930. PMID: 33108269; PMCID: PMC7853219.
2. Li J, Somers VK, Xu H, Lopez-Jimenez F, Covassin N. Trends in Use of Melatonin Supplements Among US Adults, 1999-2018JAMA. 2022;327(5):483–485. doi:10.1001/jama.2021.23652
3. Amnon Brzezinski, Mark G. Vangel, Richard J. Wurtman, Gillian Norrie, Irina Zhdanova, Abraham Ben-Shushan, Ian Ford, Effects of exogenous melatonin on sleep: a meta-analysis, Sleep Medicine Reviews, Volume 9, Issue 1, 2005, Pages 41-50, ISSN 1087-0792, https://doi.org/10.1016/j.smrv.2004.06.004.
4. Erland LA, Saxena PK. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. J Clin Sleep Med. 2017 Feb 15;13(2):275-281. doi: 10.5664/jcsm.6462. PMID: 27855744; PMCID: PMC5263083.
5. Chunjin Li, Xu Zhou, Melatonin and male reproduction, Clinica Chimica Acta, Volume 446, 2015, Pages 175-180, ISSN 0009-8981, https://doi.org/10.1016/j.cca.2015.04.029.
6. Olcese, James M, Melatonin and Female Reproduction: An Expanding Universe, Frontiers in Endocrinology, Volume 11, 2020, https://doi.org/10.3389
7. Luboshitzky R, Shen-Orr Z, Nave R, Lavi S, Lavie P. Melatonin administration alters semen quality in healthy men. J Androl. 2002 Jul-Aug;23(4):572-8. PMID: 12065466.
8. Chunjin Li, Xu Zhou, Melatonin and male reproduction, Clinica Chimica Acta, Volume 446, 2015, Pages 175-180, ISSN 0009-8981, https://doi.org/10.1016/j.cca.2015.04.029.