Most experts consider melatonin safe for short-term use, generally a few weeks to a couple of months. Beyond that, the picture gets murkier. There’s limited research on what happens when you take it for years, and one large recent study raised serious concerns about prolonged use. The right duration depends on why you’re taking it.
Short-Term Use: What the Evidence Supports
The strongest evidence behind melatonin is for brief, targeted use. For jet lag, the CDC recommends doses of 0.5 to 1 mg taken 90 minutes before bedtime, timed to your travel direction. You’d typically use it for a few days to a week while your internal clock adjusts. For general sleep trouble, most clinical trials have tested melatonin over three to eight weeks, and that’s the window where we have the clearest safety data.
In studies of adults over 55 with insomnia, a slow-release 2 mg dose taken nightly for three weeks helped people fall asleep about 15 minutes faster than a placebo. When researchers extended those trials to 26 weeks, the benefit held steady and side effects were comparable to a sugar pill. After stopping, participants in one trial showed no withdrawal effects during a two-week monitoring period. So for a defined stretch of poor sleep, a few weeks of melatonin is well-supported.
Why Long-Term Use Deserves Caution
Taking melatonin for months or years is increasingly common, but the safety data hasn’t kept pace. A large study published in Circulation tracked over 65,000 people who took melatonin for at least a year and compared them with matched controls. Over five years, those using melatonin long-term had an 89% higher rate of developing heart failure, roughly triple the rate of heart failure-related hospitalizations, and double the rate of death from any cause compared to non-users.
This was an observational study, not a controlled experiment, so it can’t prove melatonin caused those outcomes. People who take melatonin every night for years may have underlying health issues, chronic stress, or sleep disorders that independently raise cardiovascular risk. Still, the size of the study and the strength of the association make it hard to dismiss. Until more research clarifies the relationship, treating melatonin as a long-term nightly habit carries uncertain risk.
It Won’t Shut Down Your Natural Supply
One common worry you can set aside: taking melatonin doesn’t appear to suppress your body’s ability to make its own. Several studies have confirmed that supplemental melatonin doesn’t reduce your natural production. This is different from some other hormones, where external supplementation can cause the body to dial back its own output. With melatonin, your pineal gland keeps doing its job regardless of what you swallow before bed.
Melatonin in Children
For kids, the guidance is more conservative. The American Academy of Pediatrics frames melatonin as a short-term tool to help children sleep while parents work on building better bedtime routines. There’s limited data on what long-term use does in developing bodies, and because melatonin is sold as a supplement rather than a regulated medication, dosing consistency between brands can vary. If your child has been on melatonin for more than a few weeks, it’s worth revisiting whether the underlying sleep habits have improved enough to try stopping.
How to Stop Taking It
Melatonin doesn’t create physical dependence, so you won’t experience withdrawal symptoms if you stop abruptly. That said, sleep psychologists often recommend a gradual approach simply because it’s less anxiety-inducing. One common method is to lower your dose by a small amount every two weeks. Another is to skip melatonin on selected nights, gradually increasing the number of supplement-free nights. Once you’re down to a very low dose, you reduce how many nights per week you take it before stopping entirely.
The pace doesn’t matter much physiologically. Pick a rate that feels comfortable. If you stop cold turkey and sleep fine, there’s no reason to taper. If the idea of stopping all at once makes you anxious about sleeping, a gradual reduction gives you a chance to build confidence that you can sleep without it.
Dose Matters More Than You Think
Many people take far more melatonin than they need. Your body responds to very small amounts. The CDC notes that 0.5 to 1 mg is often enough to shift your sleep-wake cycle, and doses above 5 mg can actually backfire by leaving excess melatonin circulating at the wrong time of day as your body breaks it down. Oral melatonin has a half-life of 40 to 60 minutes, meaning half of it is cleared from your system within an hour. It stays active in your body for roughly five hours total.
If you’re taking 5 or 10 mg nightly, trying a lower dose before deciding melatonin “doesn’t work” is worth the experiment. A smaller dose more closely mimics what your brain produces naturally and is less likely to leave you groggy the next morning. Guidelines suggest doses up to 10 mg are safe for adults, but effective and safe are two different targets.
A Practical Timeline
If you’re using melatonin for jet lag, plan on three to five days. For a rough patch of insomnia triggered by stress, a schedule change, or a new environment, two to four weeks is reasonable. If you’ve been taking it nightly for months and sleeping well, that’s a good sign your sleep system may be ready to work on its own, and it’s worth testing a taper. If you’ve taken it for more than a few months without improvement, melatonin probably isn’t solving the actual problem, and a conversation with a sleep specialist would be more productive than continuing indefinitely.