How much melatonin should you take?

Melatonin is a circadian-system signal, not a sedative. It tells your brain "darkness is here" — which only matters if you take it at the right time. For sleep onset, that means roughly 2 hours before your target bedtime so peak blood levels coincide with your wind-down. For mid-night waking, it's at bedtime in sustained-release form. For jet lag, it's at the destination's bedtime once you've arrived.

The over-the-counter market is the messy variable. A 2017 Erland & Saxena study found 26% of US brands varied more than 10% from their labeled dose, and 25% contained serotonin contamination. Buy from a pharmacy chain, USP-verified brand, or major manufacturer — Costco's Kirkland Signature, Nature Made, and Pure Encapsulations are well-regarded.

Two things this calculator won't do: replace a doctor's advice for chronic insomnia or pediatric use, and figure out if you actually need melatonin at all. The standard sleep-hygiene checklist (consistent bedtime, dark room, no screens 60 min before bed, caffeine cutoff) outperforms melatonin for most people. Try those first.

The suggestion starts low on purpose and pairs the amount with a time, because for melatonin the when is as important as the how much. If your goal is falling asleep, the window is the hour or two before bed; if your goal is shifting a body clock that runs late, the effective timing is earlier in the evening.

Start at the low end and only adjust if it genuinely does nothing. A bigger dose is not a free upgrade: in one trial, 3 mg kept blood melatonin raised into the daytime while 0.3 mg brought it to normal night-time levels, so if you wake up groggy, go lower rather than higher. Remember too that melatonin is sold as a supplement, so actual content per pill can differ from the label, another reason to anchor on timing rather than milligrams.

Your own melatonin rises about two hours before your natural sleep onset and acts as the internal cue for night. A supplement adds to that signal, and meta-analyses (Ferracioli-Oda and colleagues; Buscemi and colleagues) find it modestly shortens the time to fall asleep, on the order of several minutes, with a small improvement in overall sleep quality.

What those numbers mean in practice is that melatonin is not a hypnotic and should not be judged like one. Its real strength is circadian: it is genuinely effective for jet lag and delayed sleep phase, where the problem is a mistimed clock, and comparatively weak when the barrier is a racing mind or 3 am waking, which have different causes.

Use the lowest dose that works, at a consistent time, and treat it as a short-term nudge rather than a nightly crutch you never re-examine. It pairs best with light management, bright morning light and dim evenings, because light is the stronger circadian signal and melatonin reinforces it rather than replacing it.

Some situations call for a clinician first: children, pregnancy, and anyone on other medications, since melatonin can interact and the long-term data in those groups is thin. If nightly melatonin is the only thing standing between you and no sleep, that is a sign to look at the underlying schedule or seek an assessment, not to keep raising the dose.