Is Melatonin Safe? All About the Popular Sleep Supplement

By Julia Reedy, MNSP, October 6, 2022

sleep circadian rhythm melatonin

Melatonin is naturally produced in the brain as a part of our sleep/wake cycle. And in recent years, researchers have realized that melatonin in supplement form has similar effects. But are melatonin supplements safe? What is the most effective and safe form to take? In general, melatonin is quite safe, though experts recommend being conservative with the dosage and the number of nights in a row that you use it. Here's a breakdown of common questions about melatonin supplements.

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What is melatonin?

Melatonin is a naturally occurring hormone that is produced in the brain to encourage sleepiness and maintain your natural wake/sleep system. It in itself doesn’t make you fall asleep, but it does have secondary effects like decreasing alertness and reducing your core body temperature. In other words, it works in tandem with other aspects of your body’s natural circadian rhythm to encourage sleep (and wakefulness in the morning).

Melatonin is actually produced in response to darkness, and light causes this production to stop. This is why sleep experts are so wary of nighttime screen use—the bright (and blue) lights emitted by our devices can interrupt natural melatonin release (and other circadian rhythm responses) to impair sleep. The image below illustrates some of the changes our bodies go through during our natural sleep/wake cycle.

And though melatonin is naturally produced by the body, research shows that supplemental sources of the hormone can actually enter our system and act much like the form our brains produce. The following sections discuss the research behind these supplements and how to best use them to improve sleep.


Do melatonin supplements really work for sleep?

There is substantial evidence that melatonin supplements do in fact increase the time spent asleep, minimize sleep onset latency (the time it takes to fall asleep), and sleep efficiency. In fact, they can even be a safe alternative to prescription sleep aids. In a randomized controlled trial, adults with high blood pressure traded their beta-blockers (a kind of prescription sleep aid) for melatonin supplements.[1] After 3 weeks, 2.5mg of nightly melatonin supplementation significantly increased total sleep time by 36 minutes and reduced sleep onset latency by 14 minutes compared to placebo. There was no significant measured tolerance to the supplement or disturbance in sleep during withdrawal, suggesting melatonin supplementation is a healthy and safe alternative to beta-blockers.[1]


Is melatonin safe for kids?

Multiple studies have found that melatonin supplements are also generally safe in children. In a randomized controlled crossover trial, children and adolescents age 1-18 years old with diagnosed atopic dermatitis (AD) were given nightly 3mg melatonin supplements.[2] After 4 weeks, sleep-onset latency shortened by 21 minutes and AD symptoms were significantly improved compared to placebo. No withdrawal symptoms or adverse effects were identified.[2]

In a separate study, parents of children with diagnosed Autism Spectrum Disorder and sleep disturbances were educated about melatonin’s effects on sleep and dosage to implement melatonin use in their children's sleep habits.[3] At follow-up visits (every 2-6 months for 1.4-1.8 years), 25% of parents reported complete erasure of sleep problems, and 60% reported improved sleep in their children with melatonin use. Only 13% of parents reported continued major concern of sleep, and parents of only 1 child reported worsening of sleep problems. Only 3 children had adverse effects after starting melatonin, which included morning sleepiness, “fogginess,” and increased involuntary urination during sleep.[3] 

Studies like these suggest that melatonin supplementation is a generally safe option for sleep improvement in children and adolescents. Beneficial effects on sleep disturbances in kids can even be found in low-dose supplements of 3mg or less nightly. 


Are there any negative effects of melatonin?

Melatonin supplements are generally safe to take, but there are some exceptions. All supplements, including melatonin, have the potential to interact with medications in an unsafe way. There is also limited evidence of melatonin’s effects in elderly dementia patients and women who are pregnant or breastfeeding, and therefore the US National Center for Complementary and Integrative Health (a part of the National Institutes of Health) does not advise that these groups take melatonin supplements.[4] For the rest of the population, melatonin’s side effects are quite limited and mild—including drowsiness, headache, dizziness, agitation, and increased bedwetting in children.[5] 

Ideal melatonin supplement

Is melatonin safe to take every night?

Multiple human studies have concluded that nightly short-term use of melatonin is safe, even in extreme doses, but experts generally recommend limiting nightly melatonin use to a two-month stretch. At that point, the need for melatonin should be re-assessed. However, a comprehensive review of available data in humans and animals found that no study reported serious adverse effects, and clinical studies even indicate that long-term administration only induces mild adverse effects comparable to placebo.[6]


What’s the ideal dose and form of melatonin?

In general, it’s best to take a low dose (1-3mg) instant release melatonin supplement to support sleep. Ideal dosages will vary for people, but it’s best to start low and increase as needed. Excessively high doses can result in daytime sleepiness—a mild side effect, but one that is easily avoidable. One systematic review of older adults (aged 55 and above) evaluated 16 studies conducted from 1980 to 2013, 9 of which were randomized controlled trials.[7] Though dosages (all oral) ranged from 0.5mg/day to 50mg/day, the researchers concluded that the lowest immediate-release doses were best at mimicking the natural effects of endogenous melatonin and circadian rhythm without threatening any physiological side effects.

Finding a reputable brand is critical for ensuring the safety and efficacy of melatonin supplements. Like other supplements, melatonin products are not closely regulated by a governing body, often resulting in discrepancies between the labels and contents of supplement bottles. In fact, one study in the Journal of Clinical Sleep Medicine found that, of 31 tested melatonin supplements, 22 (70%) had melatonin levels that were more than 10% different from what was listed on their labels. In fact, some contained over 450% of the melatonin content they claimed to have.[10] Make sure you do your research before choosing a supplement brand, and always consult with your doctor before updating your regimen.


When should you take melatonin?

Timing is also important for reaping the greatest effects from your melatonin supplement—The American Academy of Sleep Medicine found that taking melatonin supplements any time between 1.5-6 hours before bedtime can be effective.[8] Our natural melatonin levels peak about two hours before bedtime (or at least what the body thinks of bedtime), so plan to take your supplement around then.[9]


A summary of melatonin supplements' safety:

  • Melatonin is a naturally occurring hormone that works with our circadian rhythm to help us fall asleep.
  • Melatonin supplements have been found effective for increasing time spent asleep and decreasing the time taken to fall asleep in both adults and children.
  • Side effects of melatonin use are usually very mild and include drowsiness, nausea, dizziness, agitation, and bedwetting in children.
  • It’s best to start conservatively with melatonin use. Take a low dose (1-3mg) about two hours before bedtime for no longer than two months consecutively. After this period, reassess whether melatonin is still necessary.
  • For more tips on improving your night's sleep without changing your bedtime, check out our blog on the topic.




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Julia Reedy, MNSP
      • Julia is a Written Content Strategist & Editor at InsideTracker. She loves to use her experience in cutting-edge nutrition research and writing to spin complex health and nutrition topics into clear, approachable info everyone can relate to. As an inquisitive food shopper, she's constantly reading ingredient lists—and leaving shelves of backward products in her wake.














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