Melatonin has become one of the most popular sleep supplements in the US, with millions of people taking it nightly. But most people are taking doses far higher than research suggests are needed — and those higher doses may actually work less well and cause more side effects than smaller ones.
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Check interactions now →Melatonin is a hormone naturally produced by your pineal gland in response to darkness. It signals to your body that it's time to sleep — it doesn't knock you out like a sedative, it shifts your circadian rhythm. This is an important distinction: melatonin works best for falling asleep at the right time, not for staying asleep or treating insomnia rooted in anxiety or pain.
OTC melatonin in the US is typically sold in doses of 5mg or 10mg. But your body naturally produces melatonin in amounts measured in picograms per milliliter of blood — a tiny fraction of what's in most supplements. Research consistently shows that 0.5–1mg is often as effective as 5–10mg for sleep onset, with fewer side effects.
In fact, very high doses of melatonin can actually disrupt your circadian rhythm and leave you feeling groggy the next day — the opposite of what you want.
| Use Case | Recommended Dose | Timing |
|---|---|---|
| General sleep onset | 0.5–3mg | 30–60 minutes before bed |
| Jet lag prevention | 0.5–5mg | At destination bedtime for 2–5 days |
| Shift work sleep adjustment | 1–3mg | Before desired sleep time |
| Delayed sleep phase syndrome | 0.5–3mg | 5–6 hours before current sleep time |
| Children (under physician guidance only) | 0.5–1mg | 30 minutes before bed |
Melatonin is generally safe for short-term use in healthy adults. Possible side effects include:
People who should use melatonin with extra caution or under medical supervision:
Melatonin interacts with several medication classes:
Most research on melatonin safety focuses on short-term use (up to 3 months). Long-term safety data is more limited. Some concerns about long-term use:
Check melatonin against your other medications
Try MedCheck free →Short-term nightly use (weeks to a few months) is generally considered safe for healthy adults. For long-term use, it's worth discussing with a doctor, particularly to make sure the underlying sleep issue is addressed rather than just masked. Melatonin is not habit-forming in the way sedatives are.
Next-day grogginess is almost always a sign you're taking too high a dose. Try cutting your dose to 1–2mg. Taking it too late (less than 6 hours before you need to wake up) can also contribute to morning grogginess. The timing matters as much as the dose.
Melatonin is sometimes used short-term in children under physician guidance, particularly for kids with autism spectrum disorder or ADHD who have significant sleep difficulties. It should not be used casually for children without medical advice, as children's brains are still developing and the long-term effects of regular melatonin use in children are not well studied.