Medically reviewed by the VST Editorial Board. Last updated August 24, 2026. This article contains affiliate links.
Most people take melatonin for jet lag the way they take ibuprofen for a headache: swallow it when you feel bad. That is precisely the way to make jet lag last longer.
Melatonin works for jet lag, but as a clock-shifting signal rather than a sleeping pill, which means the timing of the dose matters more than the size of it. The Cochrane review of ten randomized trials found melatonin “remarkably effective” at preventing or reducing jet lag, and recommended it for adults crossing five or more time zones, particularly flying east (Herxheimer and Petrie, Cochrane Database of Systematic Reviews, 2002). The same review found doses between 0.5 mg and 5 mg similarly effective, and doses above 5 mg no better. Below is how to time it, what dose to buy, and the supplement-quality problem almost nobody mentions.
Key takeaways
- Doses from 0.5 mg to 5 mg work about equally well for jet lag; above 5 mg adds nothing (Cochrane, 2002).
- Taken at the wrong hour, melatonin causes daytime sleepiness and delays adjustment. Timing beats dose.
- Independent testing found melatonin content ranging from 83% below to 478% above the label, with serotonin in 26% of products (Erland and Saxena, Journal of Clinical Sleep Medicine, 2017).
How does melatonin actually help jet lag?
Melatonin is the hormone your brain releases in the evening to tell every clock in your body that night has started. Jet lag happens because that internal signal is still running on your departure city’s schedule while the sun outside is running on your arrival city’s.
A dose of melatonin taken in the evening of your destination fakes an early nightfall, which pulls your clock forward. That is why it helps most going east, where you need to advance your clock, and helps least going west, where you need to delay it. The human circadian period averages about 24.2 hours, slightly longer than a day, which is why stretching your day westward is naturally easier than compressing it eastward.
Say it plainly: melatonin is not sedation. If you feel nothing sleepy after taking it, that does not mean it failed. The clock shift happens whether or not you notice drowsiness.
What dose of melatonin should you take for jet lag?
Start at 0.5 mg to 3 mg. The Cochrane analysis found no advantage to going higher than 5 mg, and the practical argument for the low end is that a smaller dose is less likely to leave you groggy the next morning. The one nuance from that review: people fell asleep faster on 5 mg than on 0.5 mg, so if sleep onset is your specific problem rather than clock timing, the higher end of the range is defensible.
Most drugstore melatonin in the United States is sold at 5 mg or 10 mg, which is above the useful range for this purpose. You will often be cutting tablets. That is normal and it is not a sign you bought the wrong thing.
When exactly should you take it?
This is the whole game, and it is where most travelers get it backwards.
Flying east (New York to Paris, Los Angeles to London, US to Asia via Europe): take your dose at local bedtime on the night you arrive, and repeat for two to four nights. If you want to pre-adapt, take it in the early evening of your departure city for one to three days before you fly, moving it earlier by an hour each night.
Flying west (Europe to the US, US to Hawaii, US to South America on a westward routing): melatonin is less useful. Your task is to stay awake later, and morning light plus evening activity does most of the work. If you wake at 3 a.m. and cannot get back to sleep, a very small dose then is an option, but be aware you may be groggy after waking.
The rule that prevents the classic mistake: never take melatonin in the morning at your destination. The Cochrane authors flagged this specifically. A morning dose makes you sleepy during the day and delays adaptation, which is the opposite of the goal.
| Trip | Direction | Melatonin timing | Light strategy |
|---|---|---|---|
| New York to Paris | East, 6 zones | 0.5 to 3 mg at 22:00 Paris time, nights 1 to 4 | Morning light in Paris, sunglasses on the flight |
| London to New York | West, 5 zones | Usually unnecessary | Late afternoon light, stay up to local bedtime |
| Los Angeles to Tokyo | West across the date line, 16 hours ahead | Treat as west; anchor to local meals and light | Bright morning light delayed by a day |
| Miami to Santiago | North to south, 1 to 2 zones | Not needed | Fatigue is travel tiredness, not jet lag |
Why does the brand you buy matter more than usual?
Because in the United States melatonin is regulated as a dietary supplement, not a drug, and the testing that has been done is not reassuring. Erland and Saxena analyzed 31 commercial melatonin supplements and found actual melatonin content ranged from 83% below the label claim to 478% above it (Journal of Clinical Sleep Medicine, 2017). More than 71% of products missed their own label by more than 10%. Lot-to-lot variation inside a single product reached 465%. And 26% of the products contained serotonin, which does not belong in a sleep supplement bought off a shelf.
The practical response is not to avoid melatonin. It is to buy a product carrying a third-party verification mark such as USP Verified or NSF Certified for Sport, and to stay with the same lot for a trip rather than opening a new bottle on night three.
(Aside: this study is the reason I stopped recommending gummies for adults. Gummy formats had some of the widest deviations, and a chewable dosing format invites the exact behavior, taking another one, that the evidence says adds nothing.)
The other half of the sleep equation is temperature
Core temperature has to drop for sleep to start, and a hotel duvet in a warm room fights that. Cariloha makes bamboo sleepwear and bedding built around moisture wicking and cooling, which is the variable most travelers ignore while obsessing over supplements.
Affiliate link. We may earn a commission at no cost to you.
What works alongside melatonin?
Light is the stronger signal. Melatonin nudges the clock; light moves it. Get bright outdoor light in the morning at your destination when traveling east, and in the late afternoon when traveling west. Wear sunglasses at the times you want to avoid light, which is genuinely the most underused tool in the whole category.
Meal timing is the second lever. Eating on the destination schedule from the first day gives your peripheral clocks, particularly liver and gut, a reference point. It also reduces the digestive misery that shows up as travel constipation in the first 48 hours.
Caffeine helps you function, not adjust. Use it before noon local time, and understand it borrows from tonight.
Who should not take melatonin?
Talk to a clinician before using melatonin if you are pregnant or breastfeeding, if you take warfarin or another anticoagulant, if you take immunosuppressants, if you have epilepsy, or if you are giving it to a child. Melatonin also interacts with fluvoxamine, which sharply raises melatonin levels.
Do not drive within five hours of a dose. That is the practical safety rule that gets ignored on arrival mornings.
See a doctor if your sleep does not recover within roughly two weeks of arrival, if you are having jet lag symptoms without travel, or if you experience new daytime sleepiness severe enough to affect driving or work. Persistent symptoms point to a sleep disorder rather than jet lag. Our guide to how long jet lag lasts covers the normal timeline to compare against.
Frequently asked questions
Should I take melatonin on the plane?
Only if the flight overlaps night at your destination and you intend to sleep then. Taking it because the cabin lights dimmed is how people end up drugged into the wrong time zone.
How many nights should I keep taking it?
Two to four nights at the destination is typical for a five to eight zone shift. Longer use is not necessary for jet lag.
Is melatonin addictive?
No physical dependence has been demonstrated, and Cochrane described occasional short-term use as safe. Long daily use is a different question and worth raising with your clinician.
Does melatonin help with jet lag for short trips?
For trips under three days, many sleep specialists advise staying on home time instead of shifting at all. If you are not adapting, you do not need melatonin.
Extended release or immediate release?
Immediate release for jet lag. You are sending a timing signal, not maintaining blood levels all night.
The bottom line
Buy 0.5 mg to 3 mg immediate release from a third-party verified brand, take it at destination bedtime for the first three or four nights flying east, skip it flying west, and never touch it in the morning. Then go outside. The sunlight is doing more work than the capsule, and it is free.
Sources
- Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews. 2002. cochranelibrary.com
- Erland LAE, Saxena PK. Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine. 2017;13(2):275-281. pubmed.ncbi.nlm.nih.gov
- National Center for Complementary and Integrative Health. Melatonin: what you need to know. nccih.nih.gov
- UK Civil Aviation Authority. Physiology of flight, guidance for health professionals. caa.co.uk
This article is for general information and is not medical advice. See our medical disclaimer.
