Experiment guides → Supplements → Melatonin
Does melatonin actually help you sleep?
Quick answer: a little, on average. A meta-analysis of 19 randomized trials found melatonin shortened time-to-sleep by about 7 minutes, added about 8 minutes of sleep, and modestly improved sleep quality. That's real but small — melatonin is a signal that tells your body clock it's night, not a sedative that knocks you out. It does its best work when the clock is the problem (a delayed sleep phase, jet lag, shift work), and low doses taken well before bed tend to shift the clock as well as or better than large doses at bedtime. If you already take it, the question worth answering is whether it's doing anything for you — and that takes five nights off, then fourteen on.
"I will take my usual melatonin at the same time, 1 hour before bed, for 14 nights — after 5 nights without."
What the research says
The pooled effect: minutes, not hours. Ferracioli-Oda and colleagues pooled 19 placebo-controlled trials (1,683 participants) in primary sleep disorders. Melatonin reduced sleep onset latency by 7.06 minutes and increased total sleep time by 8.25 minutes, with a modest improvement in sleep quality. Effects were larger with longer treatment and higher doses, but never large in absolute terms (Ferracioli-Oda et al., 2013).
Who benefits depends on why sleep is poor. A 2022 meta-analysis of 23 randomized trials found melatonin improved sleep quality scores overall, with the clearest gains in people whose poor sleep came with respiratory disease, metabolic disorders or primary sleep disorders — and no significant benefit in psychiatric or neurodegenerative conditions. The cause of your bad sleep predicts whether melatonin will touch it (Fatemeh et al., 2022).
For a delayed clock, timing beats dose. In a randomized trial of 116 people with delayed sleep-wake phase disorder, 0.5 mg of melatonin taken one hour before the desired bedtime, combined with a fixed sleep schedule, advanced sleep onset by about 34 minutes and improved sleep quality versus placebo plus the same schedule. A small dose, placed early, moved the clock (Sletten et al., 2018).
What this evidence doesn't say
Trial doses, timing and formulations vary widely, which is one reason the pooled effect is small and noisy. The strongest results are in people with clock disorders; there's little evidence melatonin helps ordinary difficulty sleeping caused by stress, caffeine or an irregular schedule. Availability also varies: melatonin is over the counter in the US but a prescription medicine in much of Europe, including Denmark — this page describes research, not a recommendation to obtain it.
Run it as an experiment
- Five baseline nights without it. If you've been taking melatonin nightly, the only way to know what it does is to see your sleep without it. Rate sleep quality, restedness and time-to-sleep each morning.
- Fix the dose and move the timing earlier. Keep your usual dose (if it's above 3 mg and you wake groggy, that's worth its own note). Take it 60 minutes before your target bedtime, not at lights-out, and wake at the same time every day — melatonin shifts a clock only if the clock is held still.
- Make the pact. "I will take my usual melatonin at the same time, 1 hour before bed, for 14 nights." No caffeine after early afternoon, and dim light in the last hour — bright evening light cancels the signal.
- Morning check-ins. The three ratings, plus grogginess on waking (yes/no). Grogginess is the most common sign the dose is higher than it needs to be.
- Compare against the five nights off. If sleep onset is clearly earlier or mornings clearly better, it's earning its place — retest after a week off to be sure. If the blocks look alike, you have good evidence you can stop.
What to expect
If melatonin is doing something for you, the difference is usually a slightly earlier drift into sleep rather than a heavier night, and it grows over the two weeks as the clock moves. If you feel nothing either way, that matches the literature for people whose problem isn't circadian. Morning grogginess, vivid dreams or headaches are worth noting; they often mean the dose is too high.
Who should skip this
Don't start melatonin for an experiment if you're pregnant or breastfeeding, take anticoagulants, immunosuppressants or epilepsy medication, or have an autoimmune condition — talk to your doctor. Where melatonin is prescription-only, this test is for people whose doctor has already prescribed it; don't change a prescribed dose without asking.
Frequently asked questions
How much melatonin should you take?
Less than most products contain. Trials that shifted the body clock used 0.5 mg; the pooled sleep effect was similar across doses, and higher doses mostly add next-day grogginess. If you're on 5–10 mg, that's a reasonable thing to discuss with whoever prescribes or sells it.
When should you take melatonin for sleep?
About an hour before your intended bedtime, not when you're already in bed. Your own melatonin rises a couple of hours before habitual sleep; a dose at lights-out arrives after the signal it's meant to send. Bright light in the evening blunts it.
Is it safe to take melatonin every night?
Short-term use looks safe in trials up to several months, with mild side effects (headache, drowsiness, vivid dreams). Long-term data are thin. The bigger question is whether it's doing anything — which is exactly what the five-nights-off test answers.
Related experiments
Sources
- Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One. 2013;8(5):e63773. PubMed 23691095
- Fatemeh G, Sajjad M, Niloufar R, et al. Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials. J Neurol. 2022;269(1):205–216. PubMed 33417003
- Sletten TL, Magee M, Murray JM, et al. Efficacy of melatonin with behavioural sleep-wake scheduling for delayed sleep-wake phase disorder: a double-blind, randomised clinical trial. PLoS Med. 2018;15(6):e1002587. PubMed 29912983
Track this experiment in N of 1
A few baseline nights, then the change — and your own mornings deliver the result. No streaks, no guilt. Your first experiment is free.
Downloadon the App StoreThis page is general information about published research, not medical advice. Melatonin is a prescription medicine in many countries and interacts with several drug classes; follow your doctor's guidance and never change a prescribed dose for an experiment.