How to Beat Jet Lag: Light, Timing, and What the Research Supports

The overnight flight lands at 7 a.m., eight time zones east of home. The sun is up, and walking out into it feels like the obvious cure. Your body clock, though, still thinks it is the middle of the night, and that bright morning light can push it the wrong way, further from local time.¹

How to beat jet lag comes down to timing: start moving your body clock toward the destination before you fly, then use light and darkness after you land to keep it moving the right way. That breaks into four steps, and the first is the best researched:

1. Shift your sleep toward the destination before you fly, an hour a day for two or three days
2. Seek and avoid light according to your body’s clock
3. Switch to local time as soon as you land
4. On trips of two days or less, consider staying on home time

A 2007 US guideline from the American Academy of Sleep Medicine (AASM) rates correctly timed melatonin as a standard treatment for jet lag, but shifting your sleep with morning light before an eastward flight only as an option, its lowest grade, based on a single lab study.²

Jet lag is a clock problem, and the clock moves about an hour a day

Jet lag happens because your internal body clock stays on home time after a fast flight across time zones and resets only gradually. The US Centers for Disease Control and Prevention (CDC), in its 2026 travel health guidance for clinicians, puts the average pace at about an hour a day after flying east and an hour and a half after flying west.³

The clock sets when you feel sleepy and alert, and its main time cue is the daily cycle of light and dark. It runs slightly longer than 24 hours, so it moves later more easily than earlier, which is partly why flights east are usually harder. The sleep lost on the flight is the quicker part to repay: Eastman and Burgess, body-clock researchers in Chicago, note in a 2009 review that one night’s lost sleep can largely be made up the next night, while the misalignment lingers.¹

Take a flight six time zones east. An 11 p.m. local bedtime feels like late afternoon to your body, so you lie awake, and the next day you fade by mid-morning, when your body is at its overnight low. At an hour a day, catching up takes most of a week. Weekend late nights create the same mismatch on a small scale: social jet lag, which quietly builds sleep debt.

Count the zones and the direction before you book: one or two zones may settle in a day or two, a long trip east in most of a week, so put demanding work later in the trip where you can.

Light before your body’s low point pushes the clock later; light after it pulls it earlier

Bright light shifts the body clock in opposite directions depending on when it reaches your eyes. In a 2003 lab study of 21 adults at Harvard Medical School in Boston, light given before the body’s overnight temperature low point delayed the clock, and the same light given after the low point advanced it. Researchers plot this as a phase-response curve: the size and direction of the shift for light at each point of the body’s day.⁴

Your low point usually falls a few hours before your normal wake-up time, the CDC notes, and bright morning light after it shifts the clock earlier while evening light shifts it later.³

1. Before the low point: in the evening and the early night, bright light pushes the clock later, which helps after flying west
2. After the low point: in the late night and the morning, bright light pulls the clock earlier, which helps after flying east
3. The low point: your body’s sleepiest time, usually a few hours before your normal wake-up time; right after a long flight it is still on home time

A schematic of the light phase-response curve described in lab studies, not measured values. Shaded half: night on your body clock.

The catch is that right after a long flight, your low point is still on home time. Go back to that 7 a.m. landing, and say you usually wake at 7 a.m. at home: your low point, a few hours earlier on home time, now falls around midday at your destination. So the bright light on the drive from the airport lands before it and nudges your clock later, the opposite of what you need. Eastman and Burgess call this wrong-way shift common after long flights east; their travel plans mark hours to stay indoors, or wear very dark sunglasses.¹

To find your own turning point, start from your usual wake time at home, go back a few hours, and add the time difference after flying east (subtract it after flying west). Light before that hour on local clocks pushes you later; light after it pulls you earlier.

Before, during and after the flight: how to beat jet lag

The steps run from best-studied to least tested; all are habits, not treatments.

1. Shift your sleep toward the destination before you fly

Moving bedtime and wake time an hour a day toward the destination for two or three days before a trip, earlier before flying east and later before flying west, may cut the time needed to adjust after landing, according to the CDC’s clinician guidance.³

The study

Limited evidence

Can three earlier nights move the clock before an eastward flight? A 2003 Chicago lab trial

Eastman and Burgess’s Chicago lab moved volunteers’ sleep 1 hour earlier each day for three days and gave them three and a half hours of continuous bright, intermittent bright or dim light after waking. Measured by the evening rise in their melatonin, their body clocks moved earlier by about 2 hours with continuous bright light, about 1.5 hours with bright light in half-hour bursts (not a significant difference) and about half an hour in ordinary dim room light. Side effects on sleep were small.⁵

The authors argue a shift of a couple of hours helps twice: there is less left to shift after landing, and more of the destination’s morning light falls after your low point, where it pulls the clock the right way. This was a lab measure in healthy volunteers, not jet lag after a real flight.⁵

Going faster did not clearly help. When the same team compared a later group moving sleep 2 hours a day with the 1-hour volunteers, the clock fell behind the schedule by the third day and people struggled to fall asleep, so the authors judged the faster pace no better, though that group reported slightly fewer symptoms. Both groups in that comparison were healthy adults in their 20s and 30s with no sleep disorders, so it tells us little about older travelers, shift workers or people with health conditions.⁶

1. 3 days beforeBed and alarm 1 hour earlier; daylight soon after waking
2. 2 days beforeAnother hour earlier; bright light after waking
3. Day beforeA third hour earlier; bright indoor light if it is still dark outside
4. ArrivalLocal time from the first day

With an 11 p.m. bedtime and a 7 a.m. alarm, that means waking at 4 a.m. by the eve of the flight, which is why Eastman and Burgess suggest a light box when you wake before sunrise; they also stress that even one or two days of shifting help.¹

2. Seek and avoid light according to your body’s clock

For the first days after a long flight east, keep early-morning light dim and save outdoor time for later in the day; after a flight west, seek light in the late afternoon and evening. After the eight-zone flight above, that could mean dark glasses in the taxi, breakfast away from the window and a walk after lunch on the first day. Eastman and Burgess prefer outdoor light, far brighter than indoor lighting.¹

3. Switch to local time as soon as you land

The UK’s NHS advises moving your sleep to the new time zone as quickly as possible, setting an alarm so you don’t oversleep, going outside in daylight and sleeping only at night. On the flight, it suggests sleeping if it is night at your destination and not drinking too much caffeine or alcohol, which can make jet lag worse.⁷ The US CDC is less strict about naps: it advises against long daytime naps but says short ones may improve alertness.³ If you use caffeine to get through the first days, keep it early in your local day; how late caffeine keeps working in your body explains why.

4. On trips of two days or less, consider staying on home time

For a stay of two days or less, keeping your home sleep hours rather than adopting local ones may reduce sleepiness and jet lag, the 2007 AASM guideline says, rating this an option based on one study of a two-day layover after a westward flight. In that study, a third of the participants said they preferred switching to local hours.²

A plan for your next long flight

• Count the time zones and the direction before booking
• Two or three days before: move sleep an hour a day toward the destination
• Before flying east: bright light soon after waking. Before flying west: bright light in the evening
• On the plane: sleep if it is night at the destination; go easy on alcohol and caffeine
• After landing: seek or avoid light by your body clock, not local sunrise
• Sleep at local night; keep any daytime nap short
• Two days or less away: consider staying on home time

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Tested in the lab, unproven on real trips

The body-clock science behind these steps rests on consistent lab findings, but proof on real trips is thin. A systematic reviewsystematic review: A review that fixes its question and its rules for including studies in advance, then searches out every study that fits and weighs them together. Some systematic reviews pool the results into a meta-analysis; others describe what the studies found without combining the numbers.Full entry in the glossary of travel studies, published in 2019 by a University of Sydney team in Australia, found 13 studies with a comparison group that tested non-drug jet lag fixes on actual travelers, and most of them (9) found no significant change. The reviewers suggest the null results likely reflect poorly designed body-clock interventions and neglect of travel fatigue, and call for studies that schedule darkness as well as light.⁸

So feeling foggy on day three after a long flight east does not necessarily mean the plan failed: at about an hour a day, the clock may need more days, and nobody can yet say how many a plan saves.

Melatonin depends on timing, and the rules change at the border

Melatonin taken close to bedtime at the destination reduced jet lag in 8 of 10 trials in a 2002 Cochrane review, mainly after flights across five or more time zones.⁹ The UK’s NHS (2023) does not recommend it for jet lag, saying there is not enough evidence that it works.⁷

The review warns that melatonin taken at the wrong time, early in the day, can cause sleepiness and delay adjustment to local time, so a tablet swallowed on landing at 9 a.m. to sleep off the flight works against you. The review found doses between 0.5 and 5 mg similarly effective and higher doses no better; check with a doctor or pharmacist first. The evidence is dated: the trials ran in the 1980s and 1990s, many were reported too briefly to judge fully, the last search for new ones was in 2008, and one of the two review authors ran two of the trials.⁹

Myth

Melatonin works like a sleeping pill for jet lag, whenever you take it.

Fact

In the Cochrane review it helped when taken near local bedtime at the destination; taken early in the day, it can cause sleepiness and delay adjustment.

Its legal status depends on where you live. In the US, melatonin is a dietary supplement, regulated less strictly than a drug, and product tests have found labels that did not match the contents; in several other countries it is a prescription medicine. The US National Center for Complementary and Integrative Health (NCCIH, 2024) says people with epilepsy or on blood thinners need medical supervision, that it can linger in older people and cause daytime drowsiness, that safety in pregnancy and breastfeeding is not well studied, and that you should talk to a clinician first if you take other medicines or are thinking of giving it to a child.¹⁰

In Australia, the government-funded healthdirect service (2025) says adults over 55 can buy a slow-release form over the counter, everyone else needs a prescription, and it should not be taken before driving or operating machinery.¹¹ In the EU, under a 2012 European Commission regulation, a food containing at least 0.5 mg may carry an approved claim that it eases the feeling of jet lag when taken close to bedtime on the first day of travel and a few days after arrival.¹² In other countries, a local pharmacist can tell you what applies. For ongoing trouble sleeping at home, melatonin’s weak record for insomnia, and what works better, is a separate question.

Drowsy on arrival or sleepless weeks later: when to get help

Most jet lag fades as the body clock catches up, so the help below covers safety on arrival and sleep problems that outlast the trip. The tiers follow the UK’s NHS (2024); elsewhere, use your own health service.

• Now: do not get behind the wheel while sleepy, NHS guidance says. After a long-haul arrival, that can mean a taxi, public transport or a nap before you collect a hire car.¹³
• Soon: see a GP (family doctor) if trouble sleeping goes on for months after you are home, or makes daily life hard to manage, NHS advice says. Sleep problems that outlast the trip may belong to one of the common types and causes of insomnia.¹³
• Before your next trip: if you cross time zones often, or are thinking about melatonin or sleeping pills, raise it with a doctor, pharmacist or travel clinic.

The bottom line

Start early and steer by light. If your schedule allows, shift your sleep a few days before you fly, then time your light to your body’s low point and live on local time from the first day. The proof on real trips is thin, so treat these steps as a sensible plan that may not fully prevent jet lag.