Melatonin: Uses, Benefits, Dosage & Safety

Last updated: June 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy

Quick summary

Melatonin is the body's sleep-timing hormone, sold as a supplement mainly for jet lag and trouble falling asleep. It works best as a low-dose timing signal, not a knockout sedative — and supplement products are notorious for inaccurate dosing.

What is Melatonin?

Melatonin is a hormone the brain's pineal gland releases as darkness falls, signalling to the body that it is time to sleep. As a supplement it is one of the most popular sleep aids, used for jet lag, shift work, delayed sleep timing and difficulty falling asleep. A crucial point most marketing skips: melatonin is a circadian timing signal, not a sedative — it shifts when you feel sleepy rather than knocking you out, so timing and a low dose matter more than a big dose.

What Melatonin is commonly used for

Melatonin is used in supplements as nutritional support, not as a treatment for any medical condition.

How Melatonin works

Taken at the right time, melatonin nudges the body's internal clock, helping shift the sleep-wake cycle earlier and signalling that it is night. This is why it is most useful for jet lag and delayed sleep timing rather than as a general sedative. Because it works as a signal, very small doses are often as effective as large ones, and large doses can leave people groggy the next day or even disrupt timing.

What the evidence says

Here's an honest snapshot of what published research suggests about Melatonin — including where the evidence is limited.

The NIH's complementary-health agency notes melatonin can help with jet lag and some sleep-timing problems, with more limited evidence for general insomnia. (NIH NCCIH)
Analyses suggest melatonin modestly shortens the time to fall asleep, with low doses often as effective as high ones. (PubMed research)
Independent testing has repeatedly found the actual melatonin content of supplements varies widely from the label, sometimes by large margins. (PubMed research)

Typical dosage used in studies

Studies often use low doses of about 0.5-3 mg taken a short time before the desired bedtime; for jet lag, timing relative to the destination's night matters more than dose. More is not better. This is research information, not a recommendation.

Side effects and safety

Short-term melatonin is generally well tolerated; the most common effects are next-day grogginess, headache, dizziness and vivid dreams, often reduced by lowering the dose. Long-term safety, especially in children, is less established.

Medication interactions and who should avoid Melatonin

Medication & safety check

Melatonin can add to the effect of sedatives and may interact with blood thinners, blood-pressure medicines, diabetes medication and immunosuppressants, so people on these should check with a doctor. Avoid driving after taking it, use in children only with medical advice, and treat pregnancy and autoimmune conditions with caution due to limited data.

This is general information, not personal medical advice. If you take any medication, confirm it's safe to combine with Melatonin with your doctor or pharmacist first.

Sources & further reading

The evidence summary above is drawn from these sources. For general, authoritative background you can also consult:

Frequently asked questions

What is melatonin best for?

Jet lag and difficulty falling asleep tied to sleep timing. It's a timing signal, not a sedative, so it's less reliable for staying-asleep problems.

Is more melatonin better?

No — low doses (around 0.5-3 mg) are often as effective as high ones, and large doses can cause next-day grogginess. Timing matters more than dose.

Is melatonin safe long term?

Short-term use is well tolerated; long-term safety, especially in children, is less established, so use it under medical advice for ongoing problems.

Why do products vary so much?

Independent testing has found the actual melatonin content often differs significantly from the label, so a reputable, tested brand matters.

Can I take it with my medications?

Check first — it can add to sedatives and interact with blood thinners, blood-pressure, diabetes and immune medicines.