Is it safe to take melatonin every night?

What everyone assumes about melatonin

Melatonin is sold everywhere from gas stations to pharmacies as the "natural" sleep aid, and by one measure that framing is accurate: it is a hormone your own brain makes in response to darkness. That has made it feel categorically safer than a prescription sleeping pill, something to take nightly with no more thought than a multivitamin. Millions of adults now take it that way, for months or years at a stretch, well beyond what it was ever tested for.

What melatonin is actually proven to help with

The evidence for melatonin is real, just narrower than the marketing. NCCIH, the NIH's own research center on supplements, backs it for jet lag, delayed sleep-wake phase disorder, some pediatric sleep disorders linked to autism or ADHD, and pre-surgery anxiety. It is part of the broader wave of sleep fixes we've tracked in our look at 2026's sleep trends. For general chronic insomnia, the center is blunt: "there's not enough strong evidence to recommend its use." The American Academy of Sleep Medicine agrees, which is a big part of why "does melatonin work" and "is melatonin safe long term" turn out to be two different questions.

The new finding that complicates nightly use

In November 2025, researchers presented a study at the American Heart Association's Scientific Sessions that put a number on the long-term question. They reviewed five years of health records for 130,828 adults with chronic insomnia, comparing 65,414 who had melatonin use recorded for 12 months or more against matched peers who did not. Long-term users had a 90% higher rate of heart failure diagnosis, 4.6% versus 2.7%, were 3.5 times more likely to be hospitalized for heart failure, and were nearly twice as likely to die of any cause during the study period. "Melatonin supplements may not be as harmless as commonly assumed," said lead author Ekenedilichukwu Nnadi, M.D. "If our study is confirmed, this could affect how doctors counsel patients about sleep aids."

Why this is a signal, not a verdict

The study has real limits, and the researchers say so themselves. It has not been peer reviewed. It is observational, meaning it can show melatonin use and heart failure moving together without proving one caused the other. It could not separate out Americans buying melatonin over the counter, since the database tracked prescriptions, and it could not fully account for depression, anxiety or other sleep medications that might explain part of the link. Marie-Pierre St-Onge, who chaired the American Heart Association's own 2025 statement on sleep and cardiometabolic health and was not involved in this study, still drew a practical line from it: melatonin "should not be taken chronically without a proper indication."

The part rarely mentioned on the label

Dosing adds another layer of risk that has nothing to do with the heart failure question. A widely cited 2023 analysis found 22 of 25 melatonin gummies on store shelves were mislabeled, some containing up to 347% of the stated dose. Because supplements are not regulated the way medications are, a "3 mg" gummy might deliver a very different amount, which matters more the longer and more regularly someone takes it. NCCIH recommends starting low, around 0.5 to 1 milligram, since doses above 5 milligrams do not appear to work better and mainly raise the odds of side effects like headache, dizziness or next-day grogginess. Special caution applies to people on blood thinners or with epilepsy, who NCCIH says should only use melatonin under medical supervision, and older adults, who can experience more prolonged next-morning drowsiness than younger users.

What to do instead of reaching for a nightly dose

If insomnia is the actual problem, the American College of Physicians recommends that "cognitive behavioral therapy for insomnia (CBT-I) should be the first-line treatment for adults with chronic insomnia," ahead of any medication, in part because CBT-I "is likely to have fewer harms" than drug therapy and its skills last well beyond the four to five weeks most sleep drugs are approved for. It takes more effort than a gummy, delivered through individual sessions, group therapy or even web-based modules, which is exactly why melatonin remains so popular even where the evidence for chronic use is thinnest.

Our take

Melatonin's short-term uses, jet lag, a shifted schedule, pre-surgery nerves, hold up fine. What does not hold up is the assumption that a nightly hormone supplement is risk free simply because it is sold next to the vitamins. The new heart failure data is preliminary and unproven, but it lands on top of a supplement industry with a known labeling problem and a research base that was never built for daily, years-long use. If you need help falling asleep most nights, that is worth a real conversation with a doctor about why, not a bigger bottle.

This is general information, not medical advice. Talk to a clinician before changing anything, especially if you are pregnant, nursing, or managing a condition.