Most adults get good results from 0.5 to 5 mg of melatonin per night, with 2 mg being a common starting dose for general sleep problems. The maximum prescribed dose in clinical settings is 10 mg, but higher isn’t necessarily better, and many people respond well to doses under 1 mg.
Standard Adult Doses
For short-term insomnia, a typical starting point is 2 mg of slow-release melatonin taken one to two hours before bedtime. If that’s not enough, the dose can be gradually increased. The NHS lists a maximum of 10 mg per night for longer-term sleep issues, but most people never need that much. For jet lag, 0.5 to 3 mg is the usual range, with an upper limit of 6 mg.
The CDC notes that doses above 5 mg for jet lag are actually counterproductive. As melatonin is metabolized, excess amounts can linger in your system at the wrong time of day, working against the sleep-wake shift you’re trying to create. This points to a broader principle: melatonin works as a timing signal, not a sedative. Taking more doesn’t knock you out harder. It just raises blood levels beyond what your receptors can use.
Why Less Often Works Better
Your body naturally produces melatonin in small amounts, roughly 0.1 to 0.3 mg worth of circulating hormone at night. Even a 0.5 mg supplement already pushes blood levels well above that baseline. Research from the European Food Safety Authority suggests that doses as low as 0.3 to 1 mg are enough to reduce the time it takes to fall asleep.
There’s also a biological reason to keep the dose modest. Studies have shown that sustained exposure to very high levels can desensitize your melatonin receptors, essentially making them less responsive over time. This means that regularly taking large doses could gradually reduce the supplement’s effectiveness and, paradoxically, make sleep worse.
Doses for Older Adults
Natural melatonin production declines with age, which is one reason sleep often gets harder in your 60s and beyond. Supplementing can help, but the effective range is still lower than many people assume. A systematic review of studies in older adults found that doses between 0.5 and 6 mg improved sleep compared to placebo. Doses above 6 mg showed no additional benefit.
Starting at 0.5 to 1 mg is a reasonable approach for older adults, especially since this age group is more likely to take other medications that could interact with melatonin (more on that below).
Doses for Children
There are no official standardized dosing guidelines for children, which is part of what makes this tricky for parents. The American Academy of Pediatrics recommends starting at the lowest possible dose, typically 0.5 to 1 mg, taken 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.
Long-term use in children raises some unique concerns. A systematic review published in The Lancet found very low-certainty evidence that prolonged melatonin use (beyond seven years) might delay puberty, possibly by disrupting the natural decline in melatonin levels that normally occurs as children approach adolescence. Studies lasting two to four years showed little to no effect on pubertal development, but the data is limited. For children, melatonin is generally best used as a short-term tool rather than an indefinite nightly habit.
What Happens If You Take Too Much
Melatonin has a wide safety margin compared to prescription sleep medications. It’s very difficult to cause serious harm from a single large dose. CDC data on over 260,000 pediatric melatonin ingestion cases (many involving children who got into a bottle unsupervised) found that about 68% resulted in only minor effects like drowsiness or stomach upset. Roughly 30% showed no effects at all. Serious outcomes occurred in just 1.2% of cases.
The most common symptoms of taking too much include:
- Drowsiness and grogginess that extends into the next day
- Headaches
- Nausea or stomach discomfort
- Dizziness
Nervous system effects (excessive sleepiness, confusion) accounted for about 81% of reported symptoms in those pediatric cases, with gastrointestinal symptoms making up another 10%. Cardiovascular effects like changes in heart rate were rare, occurring in about 2.5% of cases.
Your Supplement May Not Contain What It Says
One complication worth knowing about: melatonin supplements in the U.S. are largely unregulated, and what’s on the label often doesn’t match what’s in the pill. A study analyzing 31 melatonin supplements found that more than 71% contained amounts outside a 10% margin of the labeled dose. The actual melatonin content ranged from 83% less to 478% more than what the label claimed. Even different batches of the same product varied by as much as 465%.
This means if you’re taking a “5 mg” tablet, you could be getting anywhere from less than 1 mg to over 25 mg without knowing it. If you’ve noticed inconsistent results from melatonin, the product itself may be the problem. Choosing brands with third-party testing (look for USP or NSF certification on the label) helps reduce this risk.
Timing Matters as Much as Dose
When you take melatonin affects how well it works. For general insomnia, take it 30 minutes to two hours before your target bedtime. Taking it too early or too late can shift your internal clock in the wrong direction.
For jet lag, timing depends on which direction you traveled. If you flew east, take melatonin about 90 minutes before your new bedtime to push your body clock earlier. If you flew west, taking it in the morning (by your old time zone’s clock) helps push your clock later. Taking melatonin when your body is already producing it at peak levels, roughly between midnight and 5 a.m., is less effective because you’re adding to a signal that’s already strong.
Medications That Interact With Melatonin
Melatonin isn’t risk-free for everyone. It can increase bleeding risk when combined with blood thinners or anti-clotting supplements like fish oil. It may reduce the effectiveness of seizure medications, particularly in children with neurological conditions. It can also interact with blood pressure drugs, potentially amplifying their effect.
People with autoimmune diseases are generally advised to avoid melatonin entirely, since it stimulates immune activity and could worsen conditions where the immune system is already overactive.