Can Melatonin Help Against Jet Lag

Melatonin is one of the most popular remedies for jet lag, and one of the few with solid research behind it. It does not cure jet lag, but taken at the right time it can help the body clock shift to a new time zone a little faster. Taken at the wrong time, it can make things worse. This guide summarizes what the research and the CDC’s travel health guidance say about melatonin for travelers, and what to check before trying it.

What melatonin does in the body

Melatonin is a hormone made mainly by the pineal gland, a small gland deep in the brain. Its production follows the light-dark cycle: levels stay low during the day, rise in the evening as light fades, peak in the middle of the night and fall toward morning. Bright light, especially daylight, suppresses it. Melatonin acts as a signal of “biological night” to the body’s master clock in the hypothalamus and to the many clocks in other organs.

After a long flight across time zones, melatonin is still released on home time. A traveler from Chicago in Rome may feel wide awake at local bedtime and sleepy in mid-afternoon, because the internal clock has not caught up. For the full picture of symptoms and causes, see our main article on jet lag.

What the research shows

The best-known summary of the evidence is a Cochrane systematic review published in 2002, which pooled controlled trials with travelers, airline crews and military personnel. Its main findings:

Melatonin taken close to the target bedtime at the destination reduced jet lag after flights crossing five or more time zones.
The benefit was clearest for eastward flights, which are harder for the body clock.
Doses between 0.5 and 5 mg worked about equally well for shifting the clock; 5 mg helped people fall asleep slightly faster.
Doses above 5 mg brought no extra benefit.

The CDC’s Yellow Book, the U.S. reference for travel medicine, notes that 0.5 to 1 mg is often enough to shift the body clock and advises against high doses above 5 mg. The American Academy of Sleep Medicine also lists melatonin as an option for jet lag.

Why timing matters more than dose

Melatonin has two effects. It makes people a bit drowsy for a few hours, and it nudges the body clock earlier or later depending on when it is taken. The clock-shifting effect is what helps with jet lag, and it depends entirely on timing:

Taken in the evening, before the body’s own melatonin rises, it moves the clock earlier. That is what eastbound travelers need.
Taken in the early morning by body-clock time, it moves the clock later, which can help some westbound travelers.
Taken in the middle of the biological night, when the body’s own levels are already high, it does little.
Taken at the wrong time of day, it can cause daytime sleepiness and slow down adaptation.

According to the CDC, the body adjusts by about one hour per day after eastward travel and about one and a half hours per day after westward travel without help. Melatonin and well-timed light can speed this up.

Eastward and westward travel

Flying east

Eastbound travelers, for example from the United States to Europe, need to fall asleep earlier than their body wants. The CDC describes taking melatonin about 90 minutes before the desired local bedtime at the destination, for several nights after arrival. Morning daylight at the destination helps in the same direction, while bright light in the late evening works against it.

Flying west

Westbound travelers, for example from the East Coast to Hawaii or Asia via the Pacific, need to stay up later, which most people find easier. Evening daylight helps. Melatonin plays a smaller role here; some travelers use it in the second half of the night if they wake too early, but this is a question to discuss with a doctor.

Example: New York to London

London is five hours ahead of New York. An overnight flight leaves New York in the evening and lands in London in the morning, when the traveler’s body still thinks it is the middle of the night.

Before departure: go to bed and get up an hour earlier for two or three days, if the schedule allows.
On the plane: set the watch to London time, skip alcohol, drink water and try to sleep for the first part of the flight.
Arrival day: get outside in daylight, especially late morning and afternoon. Keep any nap short, under 30 minutes.
Evening: if using melatonin after talking to a doctor or pharmacist, the timing described in the CDC guidance is about 90 minutes before a normal London bedtime.
Following days: keep a fixed local schedule for meals and sleep until symptoms fade, usually within a few days.

Product quality: what is in the bottle

In the United States melatonin is sold as a dietary supplement, not as a drug. The FDA does not check supplements for dose accuracy before they are sold. Testing has repeatedly found large differences between label and contents. A study published in JAMA in 2023 analyzed 25 melatonin gummy products and found that most did not match their labels, with some containing far more melatonin than stated. Products with a USP Verified mark have been independently tested for content and purity.

Side effects and who should be careful

Short-term use is generally well tolerated in healthy adults. Reported side effects include:

drowsiness and slower reactions
headache and dizziness
nausea
vivid dreams

Because of the drowsiness, no one should drive or operate machinery for several hours after a dose. Medical advice is especially important for:

people taking blood thinners such as warfarin, seizure medicines, diabetes medicines, blood pressure medicines or drugs that suppress the immune system
pregnant or breastfeeding women, for whom safety data are lacking
people with epilepsy, depression or autoimmune conditions
children: the CDC reported a more than fivefold rise in pediatric melatonin ingestions reported to poison centers between 2012 and 2021, so gummies belong out of children’s reach

Alcohol and melatonin together increase sleepiness and should not be combined, especially on a flight.

Other tools that work with melatonin

Light: the strongest signal for the body clock. Seek or avoid daylight according to the direction of travel.
Caffeine: useful in the morning at the destination, but its effect lasts about five hours, so avoid it from early afternoon.
Sleep medicines: prescription sleep aids can help sleep for a night or two but do not shift the body clock. They need a doctor’s prescription and are best avoided on the plane.
Meals: eating on local time supports the clocks in the digestive system.

Please note: this article is general information, not medical advice. Ask a doctor or pharmacist before taking melatonin or any other remedy, especially when taking other medicines.

Frequently Asked Questions

Does melatonin really help with jet lag?

For many adults, yes. Controlled studies show it reduces jet lag after flights crossing five or more time zones, especially eastward, when taken near the target bedtime at the destination.

Is more melatonin better?

No. Studies found doses between 0.5 and 5 mg similarly effective, and the CDC advises against high doses above 5 mg.

Can I take melatonin on the plane?

Only if it is bedtime at the destination and you can sleep afterward. Taken at the wrong time, it may delay adjustment. Avoid combining it with alcohol.