Melatonin is one of the most-used sleep supplements in the US, and most people take it without a second thought. But "it's natural" isn't the same as "it's proven safe forever." Here's what the research says about short-term side effects, long-term nightly use, and the headlines you may have seen.
Written by Vita Globe Editorial Team | Reviewed against NIH (NCCIH) guidance, AASM clinical guidelines and peer-reviewed research
Is melatonin bad for you?
For most healthy adults, short-term melatonin use appears to be low-risk. A systematic review of clinical trials found side effects were few and generally mild to moderate, with daytime sleepiness, headache and dizziness the most common[2]. The bigger unknown is long-term, nightly use: the NIH notes there isn't enough information yet to have a clear picture of melatonin's overall safety, especially at doses higher than the body makes[1].
Caveat: Most trials lasted weeks, not years, so "safe long-term" hasn't been proven either way.
Sources: NCCIH · Besag et al., CNS Drugs 2019 · Verified 2026-09-27
In this article
What is melatonin, and why do people take it?
Melatonin is a hormone your brain releases in the evening, as it gets dark. It acts less like a sleeping pill and more like a signal: it tells your internal clock that night has started. Supplements deliver the same molecule, usually in doses well above what the body makes on its own[1].
Use has grown fast. Using national survey data, researchers found melatonin use among US adults rose from 0.4% in 1999–2000 to 2.1% in 2017–2018, and use of more than 5mg a day also increased. The same authors noted that data on long-term and high-dose use are scarce[4].
So the honest starting point is this: melatonin is widely used, and widely considered gentle, but the research hasn't fully caught up with how people actually take it, which is often nightly, for months or years. For a primer on how it works, see our guide to melatonin dose, timing and what it actually does.
What are the common side effects?
A 2019 systematic review pulled together adverse events reported across randomized trials of melatonin for sleep problems. The most frequent were daytime sleepiness, headache, dizziness and feeling cold. The authors found no life-threatening side effects, and most issues resolved on their own or when melatonin was stopped[2].
The NIH lists a similar picture for adults: headache, dizziness, nausea and sleepiness[1]. In practice, the one people notice most is next-day grogginess, which is often a sign that the dose or timing isn't right for you. We cover that in how long melatonin lasts.
One more practical risk: what's in the bottle. A 2023 analysis of melatonin gummies sold in the US found 22 of 25 products were inaccurately labeled, and some contained up to about 3.5 times the stated amount[6][1]. Since supplements aren't approved by the FDA before sale, choosing a brand that uses independent testing matters.
Is it safe to take melatonin every night long-term?
This is where the evidence thins out. In the 2019 review, most trials followed people for four weeks or less, and the authors said the lack of long-term trials limits conclusions about continuous use over extended periods[2].
The longer studies that do exist are mildly reassuring. In a six-month randomized trial of a 2mg prolonged-release prescription melatonin in adults with insomnia, side effects were mostly mild, with no clinically relevant safety differences versus placebo and no withdrawal effects after stopping[7]. But that's one formulation, at a low dose, in one population, and it isn't the same as years of nightly gummies.
Sleep specialists are also cautious about melatonin as a fix for chronic insomnia. The American Academy of Sleep Medicine (AASM) suggests clinicians not use melatonin to treat sleep-onset or sleep-maintenance insomnia in adults, a weak recommendation based on limited benefit in the evidence[3]. If you need melatonin most nights to sleep, that's worth a conversation with a clinician, not just a bigger bottle.
What about the heart-failure headline?
In November 2025, researchers presented an abstract at the American Heart Association's Scientific Sessions. Using electronic health records, they compared adults with insomnia who had at least a year of recorded melatonin use with matched non-users, and reported a higher rate of heart failure among the melatonin group over five years[5].
It's worth taking seriously, and worth reading carefully:
- It was an observational study, so it shows an association, not cause and effect. The authors said so themselves.
- It was a meeting abstract, which had not been through full peer review as a journal paper.
- Melatonin use was identified from medical records, so over-the-counter use in countries like the US may have been missed, and people needing long-term sleep help may differ in health in ways the data couldn't capture.
The fair takeaway: it doesn't prove melatonin harms the heart, but it's another reason not to treat nightly, open-ended use as automatically risk-free.
Who should skip melatonin or check with a doctor first?
The NIH advises medical supervision for people with epilepsy and people taking blood thinners, and notes there's been little research on safety during pregnancy or breastfeeding[1]. Check with a clinician first if you:
- Are pregnant, trying to conceive or breastfeeding (see melatonin and pregnancy)
- Take blood thinners, seizure medication or other prescription drugs
- Have ongoing insomnia, loud snoring or daytime exhaustion, which can point to a sleep disorder that melatonin won't fix
- Are thinking of giving melatonin to a child
The honest summary
- Short-term melatonin use is generally well tolerated; side effects are usually mild[2].
- Long-term nightly safety hasn't been well studied, and one 2025 observational abstract raised questions it can't yet answer[5].
- More isn't better. Use the lowest dose that works, for occasional sleeplessness, and talk to a clinician if you rely on it most nights.
Our option
Vita Globe Melatonin 5mg Gummies – 50ct
Our standard adult option: 5mg of melatonin per two-gummy serving in a blueberry-flavored, vegan gummy, made for occasional sleeplessness rather than open-ended nightly use. Every Vita Globe product is tested by an independent third-party lab.*
Frequently asked questions
Is it bad to take melatonin every night?
It isn't known to be harmful for most adults, but it also hasn't been well studied over years[2]. Melatonin supplements are generally meant for occasional use. If you need it nightly, ask a clinician whether something else is behind your sleep trouble.
Is melatonin addictive?
Melatonin isn't considered habit-forming, and a six-month trial found no withdrawal effects after stopping[7]. More in does melatonin stop working?
Does taking melatonin stop your body from making its own?
This is a common worry, but we couldn't find good human evidence that typical supplement use shuts down your own production. What is clear is that long-term data are limited overall[1].
Can melatonin cause weird dreams?
Vivid dreams and nightmares are reported by some users, but they were uncommon in clinical trials[2].
Is melatonin safer than prescription sleeping pills?
They're different tools with different evidence. Melatonin has a mild side-effect profile in short-term studies, but the AASM doesn't recommend it for chronic insomnia[3]. The right choice depends on your situation, so talk to your doctor.
Sources
- National Center for Complementary and Integrative Health (NIH). Melatonin: What You Need To Know. Updated May 2024. nccih.nih.gov
- Besag FMC, Vasey MJ, Lao KSJ, Wong ICK. Adverse events associated with melatonin for the treatment of primary or secondary sleep disorders: a systematic review. CNS Drugs. 2019;33(12):1167–1186. doi:10.1007/s40263-019-00680-w
- Sateia MJ, Buysse DJ, Krystal AD, et al. Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2017;13(2):307–349. doi:10.5664/jcsm.6470
- Li J, Somers VK, Xu H, Lopez-Jimenez F, Covassin N. Trends in use of melatonin supplements among US adults, 1999–2018. JAMA. 2022;327(5):483–485. doi:10.1001/jama.2021.23652
- Nnadi E, Masara M, Offor R, et al. Abstract 4371606: Effect of long-term melatonin supplementation on incidence of heart failure in patients with insomnia. Circulation. 2025;152(Suppl 3):4371606. (Conference abstract; not a peer-reviewed full paper.) doi:10.1161/circ.152.suppl_3.4371606
- Cohen PA, Avula B, Wang YH, Katragunta K, Khan I. Quantity of melatonin and CBD in melatonin gummies sold in the US. JAMA. 2023;329(16):1401–1402. doi:10.1001/jama.2023.2296
- Wade AG, Ford I, Crawford G, et al. Nightly treatment of primary insomnia with prolonged release melatonin for 6 months: a randomized placebo controlled trial on age and endogenous melatonin as predictors of efficacy and safety. BMC Med. 2010;8:51. doi:10.1186/1741-7015-8-51
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
