Most adults should start with 0.5 to 1 mg of melatonin, taken 30 minutes to two hours before bedtime. That’s far less than what most supplements on store shelves contain, but lower doses are consistently more effective for the majority of people. Higher doses, like the 5 mg and 10 mg tablets widely sold in the U.S., often work no better and can actually make sleep worse.
Why Less Melatonin Works Better
Melatonin isn’t a sedative. It’s a hormone your brain already produces each evening to signal that it’s time to wind down. Supplemental melatonin works by reinforcing that signal, nudging your internal clock toward sleep. It does this by acting on a small cluster of nerve cells in the brain that control your circadian rhythm. Those cells have receptors specifically tuned to melatonin, and when the hormone binds to them, it shifts the timing of your sleep-wake cycle.
The problem with high doses is that they flood those receptors far beyond what your body naturally produces. Research shows that exposure to unnaturally high levels of melatonin can desensitize the very receptors it’s supposed to activate. In practical terms, taking too much can paradoxically make it harder to fall asleep or stay asleep. A systematic review of studies in older adults found that doses above 6 mg provided no significant sleep improvement compared to a placebo. The European Food Safety Authority recommends 0.3 to 1 mg as the range needed for a meaningful effect on how quickly you fall asleep.
Recommended Doses by Age
For healthy adults with short-term insomnia, a 2 mg slow-release tablet taken one to two hours before bed is a standard clinical dose. For ongoing sleep difficulties, the same 2 mg dose taken 30 minutes to one hour before bed is typical. If you haven’t tried melatonin before, starting at 0.5 to 1 mg lets you gauge your response before increasing.
For children, the American Academy of Pediatrics recommends starting at the lowest possible dose: 0.5 mg or 1 mg, taken 30 to 90 minutes before bedtime. Many children respond well at this level. Even children with ADHD or other conditions that affect sleep rarely need more than 3 to 6 mg. There are no formal pediatric dosing guidelines based on age or weight, so the approach is to start low and only increase if the initial dose has no effect after a week or two.
Older adults should be especially cautious. The body clears melatonin more slowly with age, so a standard dose produces higher blood levels that last longer. Starting at 0.3 to 1 mg is reasonable for anyone over 65. If you’re in this age group and taking more than 5 or 6 mg without noticeable benefit, lowering the dose may actually improve your results.
Doses for Jet Lag
Jet lag requires a slightly different approach because the goal isn’t just falling asleep on a given night. You’re trying to reset your circadian clock to a new time zone. The CDC notes that 0.5 to 1 mg is often sufficient to produce a circadian shift. Their recommended range is 0.3 to 3 mg. Take your first dose at your normal bedtime once you arrive at your destination.
Doses above 5 mg for jet lag are specifically not recommended. Higher amounts take longer to clear your system, which means excess melatonin can linger into daytime hours and send conflicting signals to your internal clock, potentially making jet lag worse rather than better.
What Happens if You Take Too Much
Melatonin has a wide safety margin, and there’s no established lethal dose in humans. But taking more than you need commonly causes headaches, dizziness, nausea, and grogginess the next day. Less common side effects include vivid dreams or nightmares, irritability, stomach cramps, short-term feelings of depression, and mood swings. Some people experience reduced alertness during the day, which defeats the purpose of taking it for better sleep.
These side effects are dose-dependent. If you’re experiencing any of them, the first thing to try is cutting your dose in half rather than stopping entirely.
The Label Accuracy Problem
One complication with melatonin dosing is that you may not be getting what the bottle says. A study highlighted by the American Academy of Sleep Medicine found that more than 71% of melatonin supplements contained an amount that was off by more than 10% from the labeled dose. The actual melatonin content ranged from 83% less to 478% more than what was printed on the label. Even different batches of the same product varied by as much as 465%.
This means a bottle labeled “1 mg” might contain anywhere from 0.17 mg to nearly 5 mg per tablet. If melatonin seems to work inconsistently for you, or if you experience side effects from a dose that previously felt fine, label inaccuracy could be the reason. Choosing products that carry a third-party testing seal (like USP or NSF) improves the odds that what’s on the label matches what’s inside.
Timing Matters as Much as Dose
Taking melatonin at the right time is just as important as taking the right amount. For general insomnia, 30 minutes to two hours before your intended bedtime is the target window. Slow-release tablets, which dissolve gradually to mimic the way your body naturally releases melatonin throughout the night, work best when taken closer to bedtime. Standard (immediate-release) tablets, which deliver the full dose at once, can be taken a bit earlier in that window since they’re primarily helping you fall asleep rather than stay asleep.
Taking melatonin too early in the evening or too late at night reduces its effectiveness. If you take it and then stay up for several more hours under bright lights, you’re working against the signal it’s trying to send. Dimming lights and avoiding screens in the hour after you take it makes a noticeable difference in how well it works.