Most adults should start with 0.5 to 2 mg of melatonin taken one to two hours before bedtime. That’s far less than the 5 or 10 mg gummies lining store shelves, and research consistently shows that lower doses work just as well, if not better, than higher ones. The reason comes down to how melatonin actually works in your body and what happens when you flood it with more than it needs.
Why Lower Doses Work Better
Your brain naturally produces melatonin in tiny amounts as darkness falls, signaling your body that it’s time to wind down. The goal of a supplement is to mimic that natural signal, not overwhelm it. The European Food Safety Authority recommends 0.3 to 1 mg as sufficient to reduce the time it takes to fall asleep, and that range aligns closely with what your body produces on its own.
Taking too much can actually backfire. When melatonin floods your receptors at levels far beyond what your brain would produce naturally, those receptors can become desensitized over time. The result is that high doses may gradually stop working or even worsen your insomnia. A systematic review of studies in older adults found that doses between 0.5 and 6 mg improved sleep compared to placebo, but doses above 6 mg showed no additional benefit at all.
Recommended Doses by Situation
The right amount depends on why you’re taking it.
General insomnia (short-term): Start with 2 mg of a slow-release tablet, taken one to two hours before bed. This is the standard starting dose recommended by the NHS for adults with temporary sleep trouble.
Ongoing insomnia: Begin with 2 mg taken 30 minutes to one hour before bedtime. If that’s not enough after a period of use, the dose can be gradually increased. The upper limit for prescription melatonin in the UK is 10 mg per night, though most people never need that much.
Jet lag: A 3 mg standard (not slow-release) tablet works for most people, with a maximum of 6 mg if needed. Take it at your target bedtime in the new time zone.
Delayed sleep phase (your body clock runs late): This one requires a different approach entirely. Cleveland Clinic recommends starting at just 0.5 to 1 mg, and the timing shifts dramatically. Instead of taking it at bedtime, you take it four hours before your desired sleep time. The goal here isn’t sedation; it’s resetting your internal clock.
Timing Matters as Much as Dose
A common mistake is popping melatonin right before climbing into bed. For general sleep problems, you need to take it 30 minutes to two hours ahead of when you want to fall asleep, depending on whether you’re using a slow-release or standard formula. Slow-release tablets are designed to dissolve gradually, so they work best taken a bit earlier. Standard tablets hit your system faster and can be taken closer to bedtime.
For circadian rhythm issues like delayed sleep phase, that window stretches to four hours before your target bedtime. Taking it too late won’t shift your body clock at all; it’ll just make you groggy at the wrong time.
Doses for Children
There are no official dosing guidelines for children, which is part of why pediatricians urge caution. The American Academy of Pediatrics recommends starting at the lowest possible dose, typically 0.5 to 1 mg, given 30 to 90 minutes before bedtime. Most children who benefit from melatonin, including those with ADHD, don’t need more than 3 to 6 mg.
Short-term use appears relatively safe in children, with morning grogginess and occasional increased nighttime urination being the most common side effects. However, less is known about long-term use, and there are open questions about whether sustained melatonin supplementation could affect growth and development during puberty. The AAP encourages parents to work closely with a pediatrician rather than dosing independently.
Adjustments for Older Adults
Natural melatonin production declines with age, which is one reason sleep often becomes more fragmented in older adults. That might seem like a reason to take more, but the opposite is true. Because the body clears melatonin more slowly with age, lower doses (0.5 to 1 mg) produce blood levels closer to what younger adults experience naturally. Starting low also reduces the risk of next-day drowsiness and the receptor desensitization that can make insomnia worse over time.
Shift Work: Limited Evidence
If you work nights and sleep during the day, melatonin’s role is less clear-cut. There is no strong evidence that taking melatonin before daytime sleep reliably helps night-shift workers. Some studies using higher doses (5 to 6 mg) found that daytime sleep lasted 26 to 56 minutes longer, but other studies found no benefit at all. One study of night-shift nurses found that 0.5 mg helped fewer than a third of participants adjust to a daytime sleep schedule.
A 3 mg dose taken before an afternoon sleep may help shift your body clock earlier, which could make it easier to fall asleep. But this strategy hasn’t been well-tested in real-world shift workers, so results are unpredictable.
Who Should Avoid Melatonin
Melatonin is widely available over the counter in the U.S. and sold as a supplement, which gives it a reputation as harmless. For most healthy adults using it short-term, the risks are genuinely low. But certain groups should be more careful. People who are pregnant or breastfeeding should avoid it, since melatonin crosses to the fetus and transfers through breast milk. Anyone taking other medications should check for interactions, particularly with blood thinners, blood pressure drugs, and diabetes medications. And if you’re about to drive or operate machinery, be aware that even doses under 0.5 mg can cause enough drowsiness to impair reaction time in some people.
The Label Problem
One practical issue worth knowing: because melatonin is sold as a dietary supplement in the U.S., it isn’t regulated with the same precision as prescription drugs. Independent testing has repeatedly found that the actual melatonin content in supplements can vary widely from what’s printed on the label, sometimes containing significantly more or less than advertised. This makes starting with a low labeled dose even more important, since the true amount you’re getting may already be higher than expected. Choosing products with third-party testing (look for USP or NSF certification on the label) can help narrow that gap.