Melatonin for Jet Lag: When to Take It, How Much, and How to Beat Jet Lag Before a Race

Melatonin for jet lag is one of the better supported uses of this hormone. A Cochrane review found that melatonin taken close to your target bedtime at the destination reduced jet lag in nine of ten trials of flights crossing five or more time zones ¹. Doses between 0.5 and 5 mg worked similarly. Timing matters more than dose, and light exposure matters at least as much as the pill.

This guide explains why jet lag happens, when to take melatonin depending on the direction you fly, how to use light and exercise, and a simple travel plan for races and training camps.

What jet lag is

Jet lag is a mismatch between your body clock and local time. Your internal clock, the circadian system, runs on roughly 24 hours and is reset mainly by light. When you fly across several time zones, the clock stays on home time for days. You feel sleepy at the wrong time, wake at 3 a.m., lose appetite and perform worse. For a primer on the clock itself, read circadian rhythm.

Two separate problems often get lumped together:

• Travel fatigue: tiredness from the trip itself, including long sitting, dry cabin air, dehydration and broken sleep. It fades after a good night's sleep.
• Jet lag: circadian misalignment that can last several days until your clock catches up ⁶.

Jet lag mostly affects trips across five or more time zones and is worse flying east than west ¹.

What the evidence says about melatonin for jet lag

The Cochrane review

The classic evidence comes from a Cochrane systematic review of ten randomized trials in airline passengers, airline staff and military personnel ¹. Key findings:

• Nine of ten trials found that melatonin taken close to the target bedtime at the destination (10 p.m. to midnight) reduced jet lag after flights crossing five or more time zones.
• Daily doses from 0.5 to 5 mg were similarly effective. People fell asleep faster and slept better with 5 mg than with 0.5 mg.
• Doses above 5 mg appeared no more effective.
• A 2 mg slow-release product worked relatively poorly, which suggests a short, high peak works better than a slow release.
• The number needed to treat was 2, and the benefit was likely greater the more time zones were crossed and smaller for westward flights.
• Taking melatonin at the wrong time, early in the day, can cause sleepiness and delay adaptation.

This review is from 2002 and many of its trials are old. Later analyses broadly agree.

A newer meta-analysis

A 2021 systematic review of foods and supplements marketed for air travel symptoms found that melatonin was one of the few ingredients with supporting evidence ². Pooled data showed less self-reported jet lag after both eastbound flights (standardized mean difference -0.76) and westbound flights (-0.66).

Evidence in athletes

Sports teams travel constantly, but research on athletes is thin. A systematic review in the British Journal of Sports Medicine found only 12 athlete-specific jet lag studies and rated the evidence for managing jet lag in athletes as low quality ⁵. It found no studies at all on managing travel fatigue. An expert consensus statement in Sports Medicine followed with practical "travel toolboxes" for before, during and after flights, while noting that the weak evidence limits how strong its recommendations can be ⁶.

When to take melatonin for jet lag

Melatonin works in two ways. It has a mild sleep-promoting effect for a few hours, and it shifts the body clock. The direction of the shift depends on when you take it.

A lab study measured this "phase response curve" for 0.5 mg and 3 mg doses ⁴. The biggest advances (moving your clock earlier) came when melatonin was taken in the afternoon or early evening, about 2 to 4 hours before your natural melatonin rise. Delays (moving the clock later) came from doses taken soon after waking, though that effect was less clear.

Flying east

You need to move your clock earlier. Practical approach based on the evidence:

1. At the destination, take melatonin around your target local bedtime for the first few nights ¹.
2. Avoid taking it in the morning or early in the day ¹.
3. If you want to start shifting before you leave, a small dose a few hours before your usual bedtime at home pushes the clock earlier ⁴. Only do this if you can tolerate some evening drowsiness.

Flying west

You need to move your clock later, which the body does more easily. Melatonin helps less here ¹, though the 2021 meta-analysis still found a benefit ². If you wake at 3 or 4 a.m., a dose at local bedtime can help you fall asleep and stay asleep. Many travelers going west manage with light and staying up until local bedtime.

What dose?

For jet lag, the studied range is 0.5 to 5 mg ¹. Start low. If you fall asleep easily but your clock does not shift, adjust the timing before you raise the dose. For the general dose-response research, including the 2024 meta-analysis showing benefits rising up to about 4 mg per day for sleep onset and total sleep ³, see melatonin dosage.

How to beat jet lag without pills: light, sleep and exercise

Light is the strongest clock signal. A review of non-drug jet lag interventions found most studies disappointing, but the authors argued this was largely because the studies scheduled light poorly and ignored darkness ⁷. Good plans control both.

• Flying east: get bright outdoor light in the morning at your destination and dim your evenings.
• Flying west: get light in the late afternoon and evening, and keep early mornings dim.
• Sleep: go to bed at local time from day one. Keep naps short and early. Use the nap calculator to time them.
• Exercise: a study of moderate treadmill exercise found that sessions at 7 a.m. or between 1 and 4 p.m. advanced the body clock, while sessions between 7 and 10 p.m. delayed it ⁸. Schedule easy sessions to push your clock in the direction you need.
• Caffeine: use it to stay alert in the local morning, and stop early enough to sleep. The caffeine cutoff calculator helps.

Race travel plan for athletes

The "one day per time zone" figure is a common rule of thumb. No trial has tested it as a threshold. Arriving earlier is better when the budget allows. If you are traveling for a training block, protect sleep in the first days and remember that adaptation happens during recovery (see supercompensation).

Safety, side effects and rules by country

Short-term melatonin use appears safe for most healthy adults ¹. A systematic review of 37 randomized trials found that the most common side effects were daytime sleepiness, headache, dizziness and feeling cold, and most resolved on their own or when melatonin was stopped ⁹.

Be careful if:

• You take warfarin or other blood thinners, or have epilepsy. Case reports raised concerns ¹, and the US National Center for Complementary and Integrative Health advises medical supervision for these groups ¹⁰.
• You are pregnant or breastfeeding. Safety research is lacking ¹⁰.
• You plan to drive or compete within hours of a dose. Daytime sleepiness is the most common side effect ⁹.

Rules differ by country. In the United States, melatonin is sold as a dietary supplement, while several other countries treat it as a prescription drug ¹⁰. In the UK, melatonin has been licensed as a medicine for the short-term treatment of jet lag ⁹. Within the EU, food supplement limits vary by member state, and some countries allow only low doses. Check your country's current rules and your destination's rules before you pack melatonin, and ask a pharmacist.

If you are a tested athlete, melatonin itself is not known to be a banned substance, but supplements can be contaminated. Use a product with third-party certification such as Informed Sport or NSF Certified for Sport, or a licensed medicine where available.

Common mistakes

• Taking melatonin at the wrong time of day. A morning dose after an eastward flight can make you drowsy and slow your adjustment ¹.
• Relying on the pill and ignoring light. Light timing is the main clock signal.
• Using slow-release products for jet lag. Immediate release looked better in the Cochrane review ¹.
• Long naps on arrival. They feel good and make the first night worse.
• Trying melatonin for the first time on race week. Test it on a training trip or at home.

The bottom line

Melatonin for jet lag has reasonably good evidence, especially for eastward flights across five or more time zones ¹². Take 0.5 to 5 mg near your target bedtime at the destination, never in the morning, and pair it with well-timed light and exercise. For athletes, the evidence base is weaker ⁵, so use melatonin as one part of a broader travel plan.

Frequently asked questions

How long before bed should I take melatonin for jet lag?

Most jet lag trials gave melatonin close to the target bedtime at the destination, roughly between 10 p.m. and midnight local time. A short, immediate-release dose taken about 30 minutes before you want to sleep fits that evidence. If you want to shift your clock earlier before an eastward trip, a lab study found the largest shifts when melatonin was taken in the afternoon or early evening, a few hours before your usual bedtime.

How many days should I take melatonin for jet lag?

Use it for the first few nights after arrival and stop once you sleep well at local time. Most people need only a short course. If you still need it after a week, the problem is more likely light exposure, schedule or another sleep issue. Occasional short-term use is what the safety evidence covers best.

Does melatonin work for westward jet lag?

It helps less than for eastward travel, according to the Cochrane review, though a 2021 meta-analysis still found less self-reported jet lag after westbound flights. Flying west lengthens your day, which the body clock handles more easily. Staying up until local bedtime and getting light in the late afternoon and evening often does most of the work. Melatonin at bedtime can help if you wake very early.

What is the fastest way to get over jet lag?

Switch to local time right away. Get bright light at the right time of day for your direction of travel, keep naps short, eat meals at local times and use caffeine only in the local morning. Add melatonin at local bedtime for flights across five or more time zones, especially eastward. Easy exercise at the right time of day can also nudge your body clock.

Can athletes take melatonin before competing?

Melatonin is not known to be a prohibited substance, but supplements can be contaminated with banned ingredients, so choose a third-party certified product or a licensed medicine. Avoid taking it within hours of training or competition, because daytime sleepiness is its most common side effect. Try it during a normal training trip first. Check local rules, because melatonin is prescription only in some countries.

Sources

1. Herxheimer A, Petrie KJ (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews.
2. Chan V et al. (2021). Efficacy of Functional Foods, Beverages, and Supplements Claiming to Alleviate Air Travel Symptoms: Systematic Review and Meta-Analysis. Nutrients.
3. Cruz-Sanabria F et al. (2024). Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. Journal of Pineal Research.
4. Burgess HJ et al. (2010). Human phase response curves to three days of daily melatonin: 0.5 mg versus 3.0 mg. Journal of Clinical Endocrinology and Metabolism.
5. Janse van Rensburg DCC et al. (2020). How to manage travel fatigue and jet lag in athletes? A systematic review of interventions. British Journal of Sports Medicine.
6. Janse van Rensburg DC et al. (2021). Managing Travel Fatigue and Jet Lag in Athletes: A Review and Consensus Statement. Sports Medicine.
7. Bin YS et al. (2019). What works for jetlag? A systematic review of non-pharmacological interventions. Sleep Medicine Reviews.
8. Youngstedt SD et al. (2019). Human circadian phase-response curves for exercise. Journal of Physiology.
9. Besag FMC et al. (2019). Adverse Events Associated with Melatonin for the Treatment of Primary or Secondary Sleep Disorders: A Systematic Review. CNS Drugs.
10. National Center for Complementary and Integrative Health (NCCIH) (2022). Melatonin: What You Need To Know. NIH NCCIH.