Supplements
Melatonin: Take Less, and Take It Earlier
The dose response data peaks around 4 milligrams and the jet lag evidence is genuinely strong. Most men take double what the research used, at the wrong time of night, for the one job melatonin is worst at.
Melatonin is the most popular sleep supplement in America and one of the most misunderstood. Walk into any pharmacy and you will find gummies dosed at 5 or 10 milligrams, sitting on a shelf marked sleep aid, right next to the antihistamines. That placement tells you what most people think melatonin is. They think it is a mild sedative.
It is not. Melatonin is a timing signal. Your brain releases it when it gets dark to tell the rest of your body that night has started. Understanding that one distinction changes how you use it, and it explains almost everything about where melatonin shines and where it disappoints.
The good news is that when you use it for the job it is actually built for, the evidence is genuinely strong. This is education, not medical advice.
What melatonin actually does
Deep in your brain sits a cluster of cells that acts as your master clock. As evening light fades, that clock signals your pineal gland to start releasing melatonin. Levels climb for hours, peak in the middle of the night, and fall before you wake. Researchers can measure the moment the rise begins, and they call it the dim light melatonin onset. It is the cleanest marker we have of where your internal clock is actually set.
Melatonin does not knock you out the way a sedative does. It tells your body what time it is. When you swallow a tablet, you are adding an artificial dusk signal on top of your own. That is why the hour you take it matters as much as the number on the bottle, and often more.
The job it is genuinely good at
Jet lag is where melatonin earns its keep. A Cochrane review pooled ten randomized trials in air travelers, airline staff, and military personnel. Nine of the ten found that melatonin taken close to the target bedtime at the destination, roughly 10pm to midnight local time, reduced jet lag after flights crossing five or more time zones. The number needed to treat came out to 2, which is a strong result for anything, let alone a supplement. The benefit was larger the more time zones you crossed and larger flying east than west (Herxheimer, 2002).
Two details from that review are worth memorizing. Doses between 0.5 and 5 milligrams worked about equally well, and doses above 5 milligrams were no better. And if you take it at the wrong time, early in your day, it can make you sleepy and actually slow your adjustment to local time. The timing is not a detail. It is the whole mechanism.
That review is from 2002, so it is old. It also remains the most thorough synthesis of the jet lag question anyone has done.
Shifting a body clock that runs late
The second real use is for men whose internal clock is simply set later than their life allows. You are wide awake at 1am and useless at 7am, every week, no matter how tired you are.
Melatonin can move that clock, and which direction it moves depends entirely on when you take it. Researchers mapped this out as a phase response curve. Taken in the hours before your natural melatonin rise, in the early evening, it shifts your clock earlier. Taken in the morning, it shifts your clock later. Small, physiological doses are enough to produce a measurable shift within a day when the timing is right (Lewy, 1997).
This is the part that gets lost. A man taking 10 milligrams at midnight because he cannot sleep is not moving his clock earlier. He is dosing at a point on the curve where there is little advance to be had, and he is taking eight times what the research needed.
What it does for ordinary bad sleep
Here is the honest part. If your problem is not travel and not a shifted clock, but just trouble falling asleep, melatonin does something real and small.
A meta-analysis of 17 studies covering 284 subjects found melatonin cut the time to fall asleep by 4.0 minutes, increased sleep efficiency by 2.2 percent, and added 12.8 minutes of total sleep (Brzezinski, 2005). Those are real, statistically significant numbers. They are also not what the packaging implies.
For chronic insomnia specifically, the American Academy of Sleep Medicine looked at the evidence for every common sleep drug and suggested clinicians not use melatonin for sleep onset or sleep maintenance insomnia. That recommendation was graded weak, which reflects thin evidence rather than proof of failure, and the same guideline graded most prescription sleep drugs weak too (Sateia, 2017). For long running insomnia, cognitive behavioral therapy for insomnia is the treatment with the best record, and it is worth asking your doctor about before you spend another year on gummies.
The dose almost nobody gets right
A 2024 dose response meta-analysis pulled together 26 randomized controlled trials published between 1987 and 2020, covering 1,689 observations in both insomnia patients and healthy volunteers. It modeled dose and timing separately, which is exactly the question that matters.
Two findings came out of it. On dose, the benefit for falling asleep faster and sleeping longer climbed and then flattened, peaking around 4 milligrams a day. On timing, the gap between taking the dose and the intended sleep episode was a significant predictor of how fast people fell asleep. The authors concluded that taking it about 3 hours before your target bedtime at around 4 milligrams likely beats the 2 milligrams 30 minutes before bed that most people default to (Cruz-Sanabria, 2024).
Put that next to the Cochrane finding that nothing above 5 milligrams helped more, and the practical range is clear. Somewhere between half a milligram and 5 milligrams covers it. The 10 milligram gummy is not buying you a stronger effect. It is buying you a longer tail of melatonin in your blood the next morning, which is where next day grogginess tends to come from.
Taking it earlier than you think feels wrong. It is the single easiest change to make, and it is the one with the most evidence behind it.
The bottle is a real problem
Melatonin is sold as a dietary supplement in the United States, which means nobody is checking the dose before it reaches you. Researchers bought 31 commercial melatonin products and measured what was actually in them.
Melatonin content ranged from 83 percent below the label claim to 478 percent above it. More than 71 percent of the products missed their own label by more than 10 percent. Lot to lot variation within a single product ran as high as 465 percent, so the bottle you buy next month may not match the one on your nightstand. And serotonin, a related compound that is a controlled substance, turned up in 8 of the 31 products (Erland, 2017).
That study is from 2017 and the market has grown a lot since. It is still the reason to buy from a brand that pays for third party testing and prints the certificate. If you are going to argue about half milligram differences, you need to know the number on the label means something.
Safety and the hard stops
Short term use looks well tolerated in the trials. The Cochrane review concluded that occasional short term use appears to be safe and that the incidence of side effects is low. The same review flagged case reports suggesting that people with epilepsy and people taking warfarin may come to harm from melatonin, and called for those interactions to be studied properly (Herxheimer, 2002).
So treat those as hard stops. If you take warfarin or any blood thinner, or you have a seizure disorder, do not start melatonin on your own. Talk to your prescriber. The same goes if you are on blood pressure medication, a sedative, or anything for mood, since the interaction data is thinner than anyone would like.
Nobody has run the long trials that would tell us what taking melatonin every night for a decade does. Absence of evidence is not evidence of harm, but it is a reason to treat nightly indefinite use as an open question rather than a settled one.
How to actually use it
For jet lag crossing five or more time zones, especially flying east: take 0.5 to 5 milligrams at your target bedtime at the destination, between about 10pm and midnight local time, starting the night you arrive. Do not take it during your daytime.
For a clock that runs late: a small dose in the early evening, several hours before you currently fall asleep, is the timing the phase response work points to. Pair it with bright light in the morning and dim light at night, which are the stronger levers anyway. This is worth planning with a doctor rather than guessing.
For occasional trouble falling asleep: start at 0.5 to 1 milligram, taken 2 to 3 hours before you want to be asleep rather than as you get into bed. If that does nothing, more is unlikely to fix it, and the problem is probably not a melatonin problem.
Buy third party tested. Skip the 10 milligram gummies. And if bad sleep has been going on for months, get it looked at, because chronic insomnia and sleep apnea both have real treatments and neither one responds to a supplement.
The verdict
Melatonin is a good tool used for the wrong job by most of the people who buy it. As a clock setter for travel and for a body clock that runs late, it has evidence that most of the supplement aisle would envy, and it is one of the few sleep aids that can say that alongside the randomized trials behind ashwagandha for stress and sleep. As a nightly sedative for chronic insomnia, it does something small and it is not the front line treatment.
The two changes worth making are boring and free. Take less, and take it earlier. Most men are doing the opposite.
That is the verdict.
This article is for general education and is not medical advice. Nothing here is intended to diagnose, treat, cure, or prevent any disease. Talk to your doctor before starting any supplement, especially if you take medication.
References
- Cruz-Sanabria F, Bruno S, Crippa A, et al. Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. J Pineal Res. 2024. https://pubmed.ncbi.nlm.nih.gov/38888087/
- Brzezinski A, Vangel MG, Wurtman RJ, et al. Effects of exogenous melatonin on sleep: a meta-analysis. Sleep Med Rev. 2005. https://pubmed.ncbi.nlm.nih.gov/15649737/
- Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002. https://pubmed.ncbi.nlm.nih.gov/12076414/
- Lewy AJ, Sack RL. Exogenous melatonin's phase-shifting effects on the endogenous melatonin profile in sighted humans: a brief review and critique of the literature. J Biol Rhythms. 1997. https://pubmed.ncbi.nlm.nih.gov/9406034/
- Erland LAE, Saxena PK. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. J Clin Sleep Med. 2017. https://pubmed.ncbi.nlm.nih.gov/27855744/
- Sateia MJ, Buysse DJ, Krystal AD, Neubauer DN, Heald JL. Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline. J Clin Sleep Med. 2017. https://pubmed.ncbi.nlm.nih.gov/27998379/
Common questions
How much melatonin should I take?
You should take less melatonin than the bottle suggests. A dose response meta-analysis of 26 randomized trials found the sleep benefit climbed and then flattened, peaking around 4 milligrams a day (Cruz-Sanabria, 2024). The Cochrane jet lag review found doses between 0.5 and 5 milligrams worked about equally well and that anything above 5 milligrams was no better (Herxheimer, 2002). That puts the useful range at roughly half a milligram to 5 milligrams. The 10 milligram gummies are not buying a stronger effect.
When should I take melatonin?
You should take melatonin earlier than most people do. In the dose response meta-analysis, the time between taking the dose and the intended sleep episode was a significant predictor of how quickly people fell asleep, and the authors suggested about 3 hours before target bedtime rather than the usual 30 minutes (Cruz-Sanabria, 2024). Melatonin is a timing signal rather than a sedative, so when you take it matters as much as how much.
Does melatonin actually help with insomnia?
Melatonin helps with insomnia a little. Pooling 17 studies in 284 subjects, melatonin cut time to fall asleep by 4.0 minutes, raised sleep efficiency by 2.2 percent, and added 12.8 minutes of total sleep (Brzezinski, 2005). Real, but small. For chronic insomnia the American Academy of Sleep Medicine suggested clinicians not use melatonin, a weak recommendation based on thin evidence (Sateia, 2017). If bad sleep has lasted months, ask your doctor about cognitive behavioral therapy for insomnia.
Does melatonin work for jet lag?
Jet lag is melatonin's strongest use. A Cochrane review of ten randomized trials found that nine of them showed reduced jet lag when melatonin was taken near target bedtime at the destination after crossing five or more time zones, with a number needed to treat of 2. The benefit was bigger flying east and bigger the more zones you crossed. Taking it at the wrong time of day can make you sleepy and slow your adjustment (Herxheimer, 2002).
Is the dose on the label accurate?
The dose on a melatonin label is often not accurate. Researchers analyzed 31 commercial melatonin products and found content ranging from 83 percent below the label claim to 478 percent above it, with more than 71 percent missing their own label by more than 10 percent. Lot to lot variation within one product reached 465 percent, and serotonin turned up in 8 of the 31 products (Erland, 2017). Buy from a brand that pays for third party testing and publishes the certificate.
Is melatonin safe to take every night?
Short term use looks well tolerated, and the Cochrane review concluded that occasional short term use appears safe with a low rate of side effects. That same review flagged case reports of possible harm in people with epilepsy and people taking warfarin (Herxheimer, 2002). Nobody has run the trials that would tell us what nightly use for years does. If you take a blood thinner, have a seizure disorder, or are on any regular medication, talk to your prescriber before starting.
