How much melatonin should you take?

For sleep onset in healthy adults, the research consistently says yes. The Brzezinski 2005 meta-analysis found no dose-response benefit above 0.3–1mg. Higher doses (3–10mg) extend the residual blood level into the next morning, which can cause next-day grogginess. Use the smallest effective dose.

Melatonin's role is to time your wind-down, not to knock you out. Peak blood levels happen ~1 hour after taking it. If you take it 2 hours before bed, the signal arrives during your wind-down — which is where it does the most useful work (cueing the rest of your circadian system to shift toward sleep). Taking it at bedtime is fine but you may not feel a clear effect for 30–60 minutes.

Mixed evidence. Short-term use (under 13 weeks) appears safe in adults per most trials. Long-term safety is less studied. The conservative approach: use it as needed for specific situations (jet lag, shift change, occasional insomnia) rather than a nightly habit. Talk to your doctor if you find yourself needing it nightly for more than a month.

Talk to a pediatrician first. The AAP position: melatonin can be useful for some specific pediatric sleep disorders (autism, ADHD-related sleep issues) but should always be MD-supervised, used short-term, and only after behavioural strategies have been tried. Tiny doses (0.3–1mg) are typical; over-the-counter chewables at 3mg+ are often dosed too high.

Regular melatonin peaks at 1 hour and clears in 4–5 hours — good for sleep onset, less useful for staying asleep. Sustained-release (often called 'extended-release' or by the brand Circadin in Europe) releases over 6–8 hours — better for mid-night waking. The downside: harder to find in the US (Circadin is prescription-only here), and some sustained-release tablets are imprecisely formulated.

Yes — several. The big ones: blood thinners (warfarin), blood pressure medications, antidepressants (especially fluvoxamine which dramatically raises melatonin levels), seizure medications, and immunosuppressants. If you take any prescription medication, talk to your pharmacist before adding melatonin.

Probably not directly. Melatonin times the circadian system — it doesn't sedate you or quiet anxiety. For anxiety-driven insomnia, the evidence-based first lines are CBT-i (cognitive behavioural therapy for insomnia), specific anxiety treatment, or short-term prescription medication. Melatonin can help with the circadian shift component if there is one, but it's not the right tool for the underlying anxiety.