Jet lag tips for before, during and after a long-haul flight

Jet lag is a timing problem, not simply a tiredness problem. A long-haul flight can carry a traveler across half the planet in a day. It cannot move the internal clock that tells the body when to sleep, eat and wake. A passenger can step off a plane in Tokyo while their body still keeps New York hours.

That gap between the body clock and local time is what jet lag is. The U.S. Centers for Disease Control and Prevention says it can occur when a trip crosses two or more time zones. The body's circadian rhythm does not reset on arrival. It shifts gradually. Until it catches up, the traveler is effectively living on two schedules at once.

The symptoms reflect that mismatch. Sleep comes at the wrong hours or not at all. Daytime brings heavy fatigue, slower thinking and trouble concentrating. Some travelers also deal with an upset stomach or changes in appetite.

For business travelers, those effects can land when they matter most. The first day or two of a trip often carries the meetings, presentations and negotiations the trip was booked for. Leisure travelers face a different cost. Every groggy afternoon is a slice of limited vacation time spent recovering rather than exploring.

Learning how to beat jet lag is less about willpower than about giving the body clock the right signals at the right time. Light and sleep timing are the main levers for shifting that clock. Melatonin, meal timing and caffeine can also help, each in a different way. Some of those signals work against the traveler if used at the wrong hour.

The 10 jet lag tips below are a selection of practical steps, not a complete or ranked list. They follow the shape of a trip. Some start several days before departure, with changes to bedtime and wake time at home. Others apply on board, from setting a watch to destination time to deciding what to drink. The rest cover the first day on the ground, when choices about naps, daylight and bedtime shape how quickly travelers recover from jet lag.

Direction matters too. Eastbound and westbound flights ask the body to make different adjustments, and several tips change with the direction of travel. Short trips raise a separate question: whether adjusting is worth the effort at all.

Illustration: Quartz

Moving your bedtime and wake time by about an hour a day for a few days before departure gives your body clock a head start on the new time zone. Shift later before a westbound trip and earlier before an eastbound one.

A plane can cross several time zones in a matter of hours. The body clock moves far more slowly. Starting the adjustment at home means part of that gap is already closed when the wheels touch down.

The direction of the shift depends on where you are going. Before a trip west, such as London to Los Angeles, go to bed an hour later each night and wake an hour later each morning. Before a trip east, such as New York to Paris, do the reverse. Go to bed an hour earlier and set the alarm an hour earlier. The return journey flips the direction again. A traveler heading home from Paris to New York would shift later in the days before that flight.

A worked example shows the scale. Paris runs six hours ahead of New York for most of the year. The U.S. and Europe change their clocks on different dates. For a few weeks each spring and autumn, the gap narrows to five hours. On the usual six-hour gap, three days of hour-a-day shifting moves a traveler's schedule three hours toward Paris time. That covers half the difference before boarding. The remaining hours are left to close after arrival.

The alarm clock does much of the work. An alarm fixes your wake time precisely, while falling asleep on command is harder. Set the alarm first and let bedtime follow. Dinner can move along with the rest of the schedule, earlier or later by about the same amount each evening.

Home lighting should match the new routine. Dim the lights as the adjusted bedtime approaches, and open the curtains soon after the adjusted wake-up time.

This approach has limits. An hour-a-day shift needs several free days before departure. It can also clash with work, school or family routines at home. A partial shift still counts. Even one or two nights of moving bedtime in the right direction leaves fewer hours to make up after landing.

Illustration: Quartz

Light is the strongest cue your body clock responds to. After an eastbound flight, seek bright light in the morning to move your clock earlier. After a westbound flight, seek light in the evening to move it later.

The clock itself sits deep in the brain. A small cluster of nerve cells called the suprachiasmatic nucleus, located in the hypothalamus, runs the body on a roughly daily cycle. It receives signals about light from the eyes. It uses those signals to keep sleep, alertness and other daily rhythms in step with the outside world. After a long flight, light at the destination becomes the main signal that tells the clock what time it is locally.

Eastbound travel means local morning arrives before your body expects it. Exposure to light early in the local day helps shift the clock earlier, toward the new schedule. A walk outside after breakfast provides that cue. So does a seat beside a bright window during the first half of the day.

Westbound travel creates the opposite problem. Local evening comes later than your body expects, and drowsiness can set in by late afternoon. Light during the late afternoon and evening helps shift the clock later. Staying outdoors before dinner, rather than retreating to a dim hotel room, puts that light to work.

The timing cuts both ways. Bright light at the wrong point in the body's cycle can push the clock in the wrong direction and slow the adjustment. This concern matters mainly on trips that cross many time zones, for example eight or more. On those routes, hours that count as morning at the destination may still fall during the body's night.

When light arrives at an unhelpful time, limiting it is part of the strategy. Wearing sunglasses outdoors or staying inside for those hours reduces how much light reaches the eyes. Strong light can then be sought once the timing works with the body clock rather than against it.

Outdoor daylight is the strongest source available to most travelers. Even on an overcast day, it is much brighter than ordinary indoor lighting. Errands on foot, a table by a window or a walk during the helpful hours all add to the signal. Repeating that pattern each day gives the body clock a steady cue during the first days in a new time zone.

Illustration: Quartz

Flying east is usually harder on the body than flying west. The internal clock finds it easier to run later than to run earlier. Eastbound travel forces the clock forward, while westbound travel lets it drift back in a direction it already favors.

The reason lies in the length of the human internal day. A 1999 Harvard study led by Charles Czeisler, published in the journal Science, put the average human circadian period at about 24 hours and 11 minutes. Without outside time cues, most people's clocks would slowly slide later each day.

That small excess shapes how travel feels. A flight west lengthens the traveler's day. Someone flying from London to New York gains five hours during most of the year, and evening simply arrives later than the body expects. Staying awake a little longer works with the clock's natural tendency. The delay is relatively easy to absorb.

A flight east does the opposite. It shortens the day and asks the body to fall asleep and wake up earlier than it wants to. Going from New York to London means bedtime arrives five hours sooner by the body's reckoning. Many travelers lie awake at the local bedtime, then struggle to get up the next morning. Advancing the clock runs against its built-in drift, and the adjustment tends to take longer.

A popular rule of thumb holds that recovery takes about one day for each time zone crossed. It is an approximation, not a measured standard. Actual recovery varies with the person, the number of zones and the direction of travel.

The asymmetry is useful when planning an itinerary. On a round trip, the harder eastbound leg can go where there is time to recover. That might mean flying before a weekend rather than the night before a major meeting. Travelers $TRV heading east can also plan a lighter first full day at the destination. Those heading west can generally expect a smoother start, though crossing many time zones in either direction still disrupts sleep.

Illustration: Quartz

Melatonin can ease jet lag when you take it close to bedtime at your destination. A Cochrane review by Herxheimer and Petrie, first published in 2002, found it effective when taken that way. The review focused on travelers crossing five or more time zones.

Melatonin is a hormone the body makes on its own. The pineal gland, a small gland in the brain, releases it in the evening as darkness falls. Levels stay high through the night. That nightly rise is one of the signals that tells the body it is time to sleep.

After a long flight, the body keeps releasing melatonin on home time. The hormone can rise during the local daytime and stay low at the local bedtime. The traveler then feels sleepy when they need to be awake and alert when they want to sleep.

A supplement aims to supply that signal at the right hour. That makes timing central. The Cochrane review looked at melatonin taken near the target bedtime at the destination. In practice, that means taking it around the time you plan to go to bed in the new time zone, on the nights after you arrive.

The right dose is less settled. In the Cochrane review, doses of 0.5 mg and 5 mg were both effective. The higher dose helped people fall asleep faster. That result does not make one amount right for every traveler. No single dose should be treated as the answer.

Product quality is another variable. In the U.S., melatonin is sold as a dietary supplement rather than as a prescription drug. As a result, quality can vary from one product to the next. Rules differ in other countries. In the U.K., melatonin is available only on prescription.

Melatonin causes drowsiness. Avoid taking it before driving or other tasks that require full alertness.

Talk to a doctor before using it, especially if you take other medication, are pregnant or plan to give it to a child. A doctor can also judge whether it makes sense for a trip that crosses fewer time zones than the trips the Cochrane review focused on.

Illustration: Quartz

Dry cabin air and in-flight alcohol do not cause jet lag, but both can make its symptoms feel worse. Drinking water steadily and keeping alcohol to a minimum on a long-haul flight helps travelers arrive without extra fatigue and headaches on top of a disrupted body clock.

Jet lag itself comes from a timing mismatch between the internal clock and local time. Fluids cannot fix that mismatch. Water can help prevent a separate problem that often travels alongside it.

Air inside an airliner cabin at cruising altitude is very dry. Cabin humidity on long flights is commonly cited as below 20 percent. That is far drier than the air in most homes and offices. Over a flight of 10 hours or more, it can leave skin, eyes and the inside of the nose feeling parched.

Mild dehydration brings its own tiredness and headaches. Those symptoms are easy to mistake for jet lag. They also add to it during the first day at the destination, when a traveler is already short on sleep.

Alcohol adds a second layer. A drink can make it easier to doze off. Later in the night, though, alcohol tends to fragment sleep, with more brief awakenings and less restful sleep overall. On a plane, engine noise, turbulence and cramped seats already break up sleep. Alcohol cuts into what little rest the cabin allows. It also increases urine output, which works against efforts to stay hydrated.

A few practical habits help. Carry an empty refillable bottle through airport security, where liquid limits apply, and fill it near the gate. Drink water at regular intervals through the flight rather than waiting to feel thirsty. Cabin crew will usually bring water on request between meal services.

Travelers $TRV who want a glass of wine with dinner can alternate each alcoholic drink with a glass of water. Skipping the nightcap before a planned sleep window keeps alcohol from disrupting the main stretch of rest on the flight. Contact lens wearers may find glasses more comfortable in the dry air. A small tube of moisturizer or lip balm can ease dry skin before landing.

Illustration: Quartz

Caffeine can ease jet lag when it is used during the destination's morning and early afternoon. Taken late in the local day, it can work against recovery. Treat coffee and tea as tools on local time, not on the schedule your body still keeps from home.

Caffeine works by blocking adenosine, a chemical that builds up in the brain during waking hours and adds to the pressure to sleep. That is why a cup of coffee can lift alertness on a groggy first morning abroad. The same effect explains why a late cup can keep a traveler awake at the hour the new time zone calls night.

How long the effect lasts depends on how quickly the body clears caffeine. Its half-life averages around five hours. That means roughly half of a dose is still circulating about five hours after drinking it. The figure varies widely from person to person, often falling somewhere between about three and seven hours. Genetics, pregnancy and some medications are among the factors that change how fast caffeine is processed.

That spread is why no single cutoff time suits every traveler. One approach is to stop caffeine several hours before the bedtime you plan to keep at the destination. People who know they are sensitive to caffeine, or who find that afternoon coffee disrupts their sleep at home, may want to stop earlier.

The same logic applies on the plane. A coffee served during what is evening at the destination can make it harder to rest during the hours you plan to sleep on board. Choosing water or a caffeine-free drink at that point keeps the timing consistent with the new schedule.

Coffee is not the only source to watch. Black and green tea, cola, energy drinks and chocolate all contain caffeine. Decaffeinated coffee still carries a small amount. A late dessert or an afternoon soft drink can add to the day's total without being obvious.

On arrival day, a morning coffee can help bridge the gap until the body clock catches up. Used on that schedule, caffeine props up daytime alertness without cutting into the first night's sleep in the new time zone.

Illustration: Quartz

Set your watch and phone to the destination's time zone as soon as you board. Then decide when to sleep and when to stay awake based on the destination's night, not the clock you left behind. This turns the flight into the first day of your new schedule instead of a gap between two.

The goal is to start nudging your body clock toward local time before the plane lands. A long-haul flight can cross many time zones, and the hours on board are some of the few you fully control. If you keep reading home time, every choice about rest stays tied to the place you are leaving. Changing the display removes that reference point and makes the destination's hour the one that counts.

Most smartphones update the time automatically once they connect to a network after landing. That does not help in the air, where airplane mode leaves the phone on its old setting. Switching off the automatic time setting and choosing the destination's time zone by hand puts the new hour in front of you during the flight. Adding the destination as a second clock does the same job. A wristwatch can be reset before takeoff.

Once the clock shows destination time, use it to plan what you do in the cabin. If it is nighttime where you are going, try to sleep, even if it is early evening at home. If it is daytime at the destination, stay awake by reading, working or walking the aisle. Do this even if the crew has dimmed the cabin for other passengers.

A few simple tools make sleeping on a plane easier. An eye mask blocks reading lights and seatback screens. Earplugs cut down engine noise and nearby conversation. Noise-canceling headphones reduce the steady low-frequency drone of the engines.

Seat choice can help as well. A window seat gives you a wall to lean against. It also keeps neighbors from waking you when they need to reach the aisle. An aisle seat suits travelers who plan to stay awake and get up often.

Some flights depart or land at hours that make a full night of sleep on board impossible. In that case, aim for a shorter rest during the destination's late-night hours. Even a partial sleep timed this way keeps the flight tied to the new schedule rather than the old one.

Illustration: Quartz

Eating breakfast, lunch and dinner on the destination's schedule is a low-risk habit that may help the body settle into a new time zone. The evidence is stronger in animals than in people. It works best as a support for other jet lag tips, not as a proven fix.

The body does not run on a single clock. A master clock in the brain sets the overall rhythm. Organs outside the brain, such as the liver and gut, also keep their own timing. Animal research shows that the timing of food can act as a cue for these peripheral clocks.

Human evidence is more limited. Researchers have not established how much eating on local time shortens jet lag for a typical traveler. That gap calls for modest expectations. Eating on a new schedule costs nothing and carries little risk for healthy adults. It also gives the day a structure that lines up with the people around you at the destination.

The practical work starts on the plane. Airline meal service follows the flight's own timetable, not the destination's. A dinner tray can arrive when it is already early morning where you are going. Travelers $TRV can decline a meal or eat only part of it. They can also save a packed snack for a time that matches local mealtimes. Bringing food from home makes it easier to wait without going hungry.

On arrival, aim for breakfast in the local morning, even if appetite is low. A light meal still marks the start of the day. Lunch and dinner can then follow at roughly the hours locals keep.

Hunger can show up at odd hours in the first days, while appetite still tracks home time. A small snack can bridge the gap until the next local mealtime. A large meal in the middle of the local night runs counter to the new schedule. Keeping the evening meal at a reasonable local hour leaves room for sleep that night.

People with diabetes or other conditions tied to meal timing should plan any changes with a doctor before the trip. Medication schedules may also need adjusting when crossing time zones.

Illustration: Quartz

For a stay of about two or three days, many travel guides advise keeping your body on home time instead of trying to adjust. This is common guidance rather than a measured threshold. It rests on a practical point: a short trip can end before the body clock catches up with local time.

Adjusting to a new time zone takes days, not hours. A traveler who spends the first two days shifting toward local hours may fly home just as that shift starts to take hold. The return flight then brings a second round of adjustment. One short trip can produce two separate stretches of disrupted sleep.

Staying on home time works best when the schedule allows some control. The idea is to treat the destination's clock as a calendar for appointments. Sleep and wake times stay close to what they would be at home.

Scheduling is the main tool. Put important meetings and client pitches in the hours that line up with your normal daytime alertness back home. London is five hours ahead of New York for most of the year. A New York-based traveler used to a 9 a.m. start would reach that point around 2 p.m. London time. For that traveler, London afternoons are a better slot for high-stakes work than early London mornings.

The same logic works in reverse. Hours that fall during your home night suit low-stakes tasks, or sleep if the itinerary permits it. Ask hosts whether a meeting can move before you book flights. Rearranging a calendar in advance is simpler than renegotiating it after you land.

This approach does not suit every trip. If the destination's working day falls mostly during your home night, staying on home time may mean missing the events you traveled for. A partial shift toward local hours is a reasonable compromise in that case.

A few practical tools support this approach. A hotel room with blackout curtains makes it easier to sleep at unusual local hours. A second clock on your phone set to home time shows when your body expects to be awake. That makes it simpler to slot tasks around your alert hours.