The short answer: timed melatonin and timed light exposure are the only jet lag remedies with strong evidence behind them. Low dose melatonin at your destination bedtime helps you fall asleep on local time, and bright light at the right hour shifts your body clock in the right direction. Everything else helps less, or helps only in specific cases.
Jet lag is not tiredness from a long flight. It is a mismatch between your internal body clock and the local time where you landed. Your clock runs slightly longer than 24 hours, about 24.18 hours on average, which is why it is easier to stay up later than to fall asleep earlier, and why flying east hurts more than flying west. The CDC puts average adjustment at about 1 hour per day after flying east and about 1.5 hours per day after flying west. A six hour eastward jump takes roughly six days to resolve if you do nothing to speed it along.
This article is general health information, not medical advice. Talk to your doctor before taking any supplement, especially if you take medication, are pregnant, or have a health condition. Melatonin can interact with some medicines, and supplement contents are not regulated the way medicines are.
Supplements: what the evidence says
Melatonin: the one with real evidence
Melatonin is the only jet lag supplement with strong trial evidence. A 2002 Cochrane review pooled ten randomized trials and found that melatonin taken close to the destination bedtime reduced jet lag in 8 of the 10 trials. The reviewers called it remarkably effective, estimating that only about two travelers need to take it for one to benefit. The American Academy of Sleep Medicine lists timed melatonin as a standard treatment for jet lag disorder, its strongest recommendation tier.
Timing matters more than dose. Melatonin signals to your body clock where night falls; it is not a sleeping pill. Taken at the wrong time of day it can push your clock in the wrong direction and leave you groggy at the wrong hour. Take it at bedtime in the destination time zone, starting on the night you arrive and continuing for the first few nights.
Dose matters less than the bottle suggests. In the Cochrane trials, doses from 0.5 mg to 5 mg worked similarly well. The CDC says 0.5 to 1 mg is often enough, and recommends against doses above 5 mg, because excess melatonin can still be circulating at the wrong point in your cycle the next day. Fast-release tablets beat slow-release versions.
Two warnings. Melatonin is not regulated by the FDA in the United States, so the amount in the tablet can vary from the label. Buy from a reputable brand and keep the dose low. And the evidence is not unanimous: two of the ten Cochrane trials found no benefit, and the UK’s NHS does not recommend melatonin for jet lag. In the UK it is prescription only, so sort it out before you travel.
Caffeine: a timing tool, not a cure
Caffeine does not reset your body clock. It keeps you awake during the local day, which matters, because staying awake until local bedtime builds the sleep pressure that helps you fall asleep that night. Used well it is one of the most useful tools you have. Used late it works against you.
The CDC suggests 200 mg of caffeine every four hours during daylight hours at your destination, roughly two cups of brewed coffee, stopping six hours before bedtime. Caffeine has a half-life of about five hours, so an afternoon coffee is still half present at bedtime.
There is a second reason to respect the cutoff. A 2015 study in Science Translational Medicine gave five volunteers a double espresso’s worth of caffeine three hours before their usual bedtime, under controlled laboratory conditions. It delayed their circadian melatonin rhythm by about 40 minutes, nearly half the shift from three hours of bright evening light. The study was small, but it shows caffeine is not just a stimulant. In the evening it pushes your clock later, the opposite of what eastbound travelers need. The rule: caffeine in the local morning and early afternoon, none in the evening.
Magnesium: weak evidence, modest effect at best
Magnesium is marketed heavily as a sleep aid, and the evidence does not match the marketing. A 2021 systematic review pooled three small randomized trials in 151 older adults with insomnia. People taking magnesium fell asleep about 17 minutes faster than those on placebo, and total sleep time rose by about 16 minutes, a difference that was not statistically significant. All three trials were rated at moderate to high risk of bias, and the evidence was graded low to very low quality. A broader 2026 review of twelve trials agreed: magnesium may help some self-reported sleep outcomes in some adults, but the findings are inconsistent, and the evidence does not support it as a routine insomnia treatment.
No trial has tested magnesium specifically for jet lag. If you already take it and sleep well on it, there is no reason to stop for a trip. But there is no evidence it shifts your body clock or shortens jet lag.
Vitamin D: worth checking, not a quick fix
Low vitamin D is consistently linked to poor sleep in observational studies, and a 2022 meta-analysis of three randomized trials found that supplementation improved sleep quality scores in people who were deficient. But no trial has tested vitamin D for jet lag, and correcting a deficiency takes weeks, so starting it the night before a flight will do nothing for that trip. The honest takeaway is longer term: if you fly often and sleep poorly, ask your doctor to check your vitamin D level. Fixing a real deficiency may improve your sleep generally. It will not reset your clock after a long haul flight.
Electrolytes and hydration: drink water, skip the hype
Cabin air is dry, and dehydration worsens fatigue, headaches, and the general misery of jet lag. The CDC notes that alcohol and caffeine both cause dehydration, which can further worsen jet lag. The NHS advice is simpler: drink plenty of water. Electrolyte drinks are not harmful, but there is no evidence they specifically reduce jet lag, and plain water does the main job. The bigger wins are avoiding alcohol in flight, which fragments your sleep even though it helps you fall asleep faster, and keeping caffeine to the morning at your destination.
Non-supplement tips that actually move the clock
Light exposure: the strongest signal you control
Light is the most powerful cue for resetting your circadian clock. The rule depends on direction, and it reverses the instinct most travelers have.
Flying east, seek bright light in the destination morning and avoid bright light in the late evening. Morning light after your body’s low point, roughly two to four hours before your habitual wake time, pushes your clock earlier, which is what eastward travel needs. Evening light pushes it later and prolongs the jet lag. Flying west, do the opposite: avoid bright early morning light and seek light in the afternoon and evening.
Get outside on arrival day. Even an overcast sky delivers far more light than a hotel room. A walk outside in the morning after an eastbound flight is the single most effective free thing you can do.
Shift your sleep before you fly
You do not have to wait until landing to start adjusting. The CDC suggests shifting your sleep by one hour per day toward the destination time zone in the two to three days before the trip: one hour earlier each day before flying east, one hour later before flying west. Shift light and meals along with sleep. Going to bed an hour earlier while staring at bright screens until midnight will not move your clock.
Meal timing: eat on local time
Your gut has its own clock, and it responds to when you eat. The CDC advises timing your meals to the destination time zone, starting during the flight. If you land at 6 a.m. local time and your body thinks it is midnight, eat breakfast anyway. Your gut clock will start to follow.
You may have heard of the Argonne diet, a feast and fast protocol from Argonne National Laboratory in the 1980s. It was tested once, in a 2002 study of 186 National Guard personnel crossing nine time zones, and those who followed it reported jet lag less often. But the participants chose the diet themselves rather than being randomly assigned, which makes the results hard to trust, and no high quality trial has tested it since. A simpler 12 to 16 hour fast before your first meal at destination breakfast time is popular with frequent flyers, but the evidence is thin. Eating on local time is the part with solid support. Fasting is not suitable for everyone, including people with blood sugar problems.
Exercise timing: morning moves you earlier, evening moves you later
Exercise affects the body clock too, and the timing decides the direction. A 2019 study in the Journal of Physiology put 99 adults through one hour of moderate treadmill exercise at different times of day for three consecutive days. Morning exercise at 7 a.m. and afternoon exercise between 1 p.m. and 4 p.m. shifted the clock earlier. Evening exercise between 7 p.m. and 10 p.m. shifted it later. The shifts were comparable in size to bright light of the same duration.
For travelers the application is simple. After an eastbound flight, exercise in the morning at your destination. After a westbound flight, an evening workout helps delay your clock. A smaller 2016 study found that bright light and exercise together shifted the clock more than either alone, which is another reason to take that morning walk or run outside. Our airport gym finder lists gyms at and near all 19 airports we cover, with equipment and day pass prices where published.
In-flight sleep strategy
Sleep on the plane only when it is night at your destination. Sleeping through what should be local daytime just moves the problem to the hotel. Set your watch to destination time when you board. On an overnight eastbound flight, eat lightly, skip alcohol, and sleep through the middle portion of the flight. An eye mask and earplugs or noise cancelling headphones make a real difference. On a daytime westbound flight, stay awake, get up and move, and save your sleep for the destination night.
Naps on arrival: short or not at all
A short nap of 20 to 30 minutes can restore alertness without wrecking your first night. Longer naps reduce the sleep pressure you need to fall asleep at local bedtime, and the CDC warns they can interfere with nighttime sleep. The NHS goes further and advises against daytime sleep altogether after landing. The practical compromise: if you are falling asleep standing up, take a 20 minute nap, set an alarm, and get outside into daylight right after. If you land early and your hotel room is not ready, a day room near the airport beats an airport bench. Our airport day rooms guide lists hotels near each airport that sell day use.
Anchor sleep: the short-trip strategy
If your trip is only one or two days, the CDC’s advice is not to adapt at all. Stay on your home schedule for sleep, meals, and activity, and you avoid paying the adjustment cost twice.
This is where the anchor sleep concept helps. In a 1981 study, chronobiologists Minors and Waterhouse found that keeping just four hours of sleep at the same clock time every day stabilized volunteers’ circadian rhythms, even when the rest of their sleep moved around. Aircrew have used the idea ever since on short layovers: protect one fixed block of sleep on home time, and let the rest of the schedule flex around it. For a two day business trip, that means sleeping and eating on home time and not fighting your body to adapt to a zone you will leave in 48 hours. The evidence comes from small laboratory studies rather than large travel trials, so treat it as a well reasoned strategy rather than a proven cure.
Eastbound vs westbound: the plans side by side
Eastbound travel is harder because your clock has to advance, to fall asleep earlier and wake earlier, which fights its natural tendency to drift later. Westbound travel asks your clock to delay, which comes more naturally.
Flying east: shift sleep one hour earlier per day for two to three days before the trip. On the flight, sleep during destination nighttime and avoid bright evening light. On arrival, get bright morning light, exercise in the morning, and take caffeine in the morning only. Take low dose melatonin at destination bedtime for the first few nights. Stay up until local bedtime.
Flying west: shift sleep one hour later per day for two to three days before the trip. On the flight, stay awake during destination daytime and avoid bright early morning light. On arrival, seek light in the afternoon and evening. Exercise in the evening if you can. Caffeine in the afternoon is fine, but stop six hours before bed. Melatonin is less often needed westbound, but a low dose at bedtime can still help if you struggle to fall asleep.
A sample plan: day before, day of, arrival day
Day before (eastbound example, New York to London): go to bed and wake one hour earlier than usual. Eat dinner one hour earlier and keep lights dim in the evening. Pack your eye mask, earplugs, and melatonin in your carry-on, not your checked bag.
Day of travel: set your watch to London time when you board. Eat meals on destination time. Drink water through the flight and skip alcohol. Sleep during the middle of the overnight flight. Wake for breakfast service, which lands close to London morning. On landing, get outside into daylight. Walk, do not nap.
Arrival day: stay up until local bedtime. Caffeine in the morning only. Exercise in the morning, outside if possible. Eat dinner at a normal local time. Dim the lights an hour before bed. Take low dose melatonin at bedtime. Sleep in a dark, quiet room. If your hotel is noisy, our best airport sleep guide ranks the quietest airport hotels at each airport we cover.
Frequently asked questions
What is the best supplement for jet lag?
Melatonin, at low dose at your destination bedtime. It is the only supplement with strong trial evidence for jet lag, supported by a Cochrane review of ten randomized trials and a standard recommendation from the American Academy of Sleep Medicine. Timing matters more than dose.
How much melatonin should I take for jet lag?
The trials found doses from 0.5 mg to 5 mg similarly effective, and the CDC says 0.5 to 1 mg is often enough. Higher doses do not work better. Talk to your doctor before taking it, especially if you take other medication.
Does magnesium help with jet lag?
There is no trial of magnesium for jet lag. The general sleep evidence is weak: a 2021 meta-analysis found people fell asleep about 17 minutes faster, but the trials were small and low quality, and a 2026 review concluded the evidence does not support magnesium as a routine sleep treatment.
Should I take caffeine to beat jet lag?
Caffeine helps daytime alertness but does not reset your clock, and in the evening it can delay it. Use it in the local morning and early afternoon, and stop at least six hours before bedtime.
How long does jet lag last?
The CDC puts average adjustment at about 1 hour per day after flying east and 1.5 hours per day after flying west. A six hour eastward shift takes roughly six days to fully resolve without intervention. Timed light, melatonin, and pre-trip shifting shorten that.
Does fasting help with jet lag?
The evidence is thin. The Argonne feast and fast diet was tested once in military personnel who chose the diet themselves, not in a randomized trial, and no high quality trial has followed. Eating your meals on destination time is the part with solid support.
Jet lag is a circadian rhythm sleep disorder. For the clinical evidence behind melatonin and light therapy, and when jet lag needs a doctor, see Jet Lag: What Melatonin and Light Therapy Actually Do.
Want to go deeper on the mechanisms? Biohacking Jet Lag: Reset Your Body Clock With Timing covers the phase-response levers: light, melatonin, exercise, meals, and anchor sleep.
Sources
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- Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews, 2002. https://pubmed.ncbi.nlm.nih.gov/12076414/
- Morgenthaler TI, Lee-Chiong T, Alessi C, et al. Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders: An American Academy of Sleep Medicine Report. Sleep, 2007; 30(11): 1445-1459.
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- Burke TM, Markwald RR, McHill AW, et al. Effects of caffeine on the human circadian clock in vivo and in vitro. Science Translational Medicine, 2015; 7(305): 305ra146. https://pubmed.ncbi.nlm.nih.gov/26378246/
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- Youngstedt SD, et al. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise. Journal of Circadian Rhythms, 2016; 14(1): 2. https://doi.org/10.5334/jcr.137
- Minors DS, Waterhouse JM. Anchor sleep as a synchronizer of rhythms on abnormal routines. International Journal of Chronobiology, 1981; 7(3): 165-188. https://pubmed.ncbi.nlm.nih.gov/7239725/
- Reynolds NC, Montgomery R. Using the Argonne diet in jet lag prevention: deployment of troops across nine time zones. Military Medicine, 2002.
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a Systematic Review and Meta-Analysis. BMC Complementary Medicine and Therapies, 2021.
- Lopresti AL, et al. Magnesium supplementation for sleep and insomnia: a systematic review, 2026. (Reviewed via secondary summaries.)
- Mirzaei-Azandaryani Z, et al. The effect of vitamin D on sleep quality: a systematic review and meta-analysis, 2022.
- NHS. Jet lag. https://www.nhs.uk/conditions/jet-lag/
This article is general health information, not medical advice. Talk to your doctor before taking any supplement or changing medication. If sleep problems persist for weeks after travel, see your doctor.