How to Beat Jet Lag.

If you do one thing about jet lag, make it this. Light is the strongest signal your body uses to set its clock, far stronger than meal times, exercise, or sheer willpower. It is 3am and you are awake. Not drifting, not dozing. Awake the way you are at ten in the morning after coffee. The room is dark, the street outside is silent, and your body has decided, with total confidence, that it is the middle of the afternoon and there are things to be getting on with.

You lie there and do the math. It is early evening back home. Of course you are awake. Your body is not broken. It is doing exactly what it always does at this hour. The only problem is that this hour is happening in the wrong place.

Most jet lag advice is wishful thinking dressed as science. Drink water, it says, as though dehydration were the issue. This is the plain version: what jet lag is, why flying east wrecks you more than flying west, and the short list of things that help, kept separate from the long list of things that mostly do not.

What jet lag is

Your body runs on an internal clock, set to roughly a 24-hour cycle, that controls when you feel alert and when you feel like sleeping. It takes its main cue from light. Cross several time zones in a few hours and that clock stays set to where you started, while the sun outside follows a completely different schedule.

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Several has a number on it: three. Under three zones you are tired rather than jet lagged, and a north to south flight of the same eleven hours does not cause it at all, because nothing about the clock has moved. What that flight gives you is travel fatigue, which feels similar on the day and is gone by the next one.

It is more than feeling sleepy at the wrong time. Jet lag shows up as a flat, foggy head that will not sharpen, hunger that arrives at strange hours, a short fuse, and a digestive system running on a schedule of its own. The tiredness is the headline. The rest is the part that takes the edge off the first couple of days.

Your body clock does not care that the plane has landed. It is still keeping office hours in the city you left, brewing the coffee and opening the blinds at what it firmly believes is the correct time, paying no attention at all to the actual sky outside the window.

That day per zone is the middle of a range rather than a rule. A day to a day and a half per zone is the usual estimate, and it stretches at both ends: eastbound is slower than westbound, and travelers over sixty tend to take longer again, because the melatonin rhythm that does the resetting gets weaker and less regular with age. Seven zones east at the slow end of that is closer to a week than to a long weekend, which is the number to plan the first half of a trip around.

Why going east hurts more than going west

Not all jet lag is equal. The direction you fly changes how hard the adjustment is, and the difference is not small. Left to itself your body clock drifts later by up to an hour and a half a day, and earlier by only about an hour, so the same gap closes roughly a day sooner flying west. Around three quarters of people say east is the worse of the two.

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Flying west, you stay up later and sleep in, which your body finds fairly agreeable. Flying east, you have to fall asleep and wake earlier than your body wants, which it resists. A long haul east to the islands of Palawan lands you somewhere your body insists it is the middle of the night while everyone around you is ordering lunch.

Picture a seven-hour shift east, which is what a flight from Europe to the Philippines is. You land in the afternoon, wrecked, push through to a local bedtime, and sleep hard for four hours before snapping awake at 2am. The next night you make it to 3am, then 4, then finally a more or less normal night somewhere around the end of the first week. Go west instead. The same gap tends to sort itself a day or two faster with much less drama.

Check your own shift before you use any of this, because the number changes the advice. From the American east coast the same trip is twelve or thirteen hours, and past roughly twelve the sensible move flips: the body closes the gap faster going later rather than earlier, so you follow the westward protocol on an eastward flight.

You can cross ten time zones in a single day. Your body clock moves about one zone per day, and it never agreed to the flight.

I once fell asleep at six in the evening in Tokyo, certain I had finally beaten it, and woke at one in the morning fully rested and ready to begin my day. Alone, in the dark, with strong and detailed opinions about breakfast.

Light is the one lever that works

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The whole thing turns on timing. Morning light shifts your clock earlier, which is what you want flying east. Evening light shifts it later, which is what you want flying west. Get the timing wrong and you can deepen the jet lag instead of fixing it, which is why blindly chasing sunlight at any hour is not the move.

Going east versus going west, in practice

Flying east, get out into morning light and go easy on bright light late in the evening, including the long scroll in a dark room that is somehow always lit by a phone. Flying west, do the opposite: seek light in the late afternoon and early evening, and ease off the very early morning sun.

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Outdoor daylight is what counts here. Put numbers on it and the argument makes itself. A well-lit office is 300 to 500 lux. An overcast sky is around 1,000. Direct sun is 32,000 to 100,000. So stepping outside on a gray morning gives you two or three times the light of the brightest room you have access to, and stepping into sunshine gives you up to two hundred times it.

A walk does far more than sitting by a window, and no lamp is going to close that gap. Twenty to thirty minutes outside at the right end of the day is worth more than any amount of squinting at a desk lamp and hoping.

There is something grand about being awake for a sunrise you did not set an alarm for, in a city that is still half asleep. It would be grander if your body had not chosen 4am to arrange it, and if you were not going to pay for the whole performance with a slow collapse in a museum at three in the afternoon.

What mostly does not work

A lot of jet lag advice survives because it sounds responsible, not because it does much.

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The classic advice to start shifting your sleep three days before you fly assumes a life in which you control your own evenings. Most people begin a trip already slightly broken, having stayed up the night before packing the things they meant to pack a week earlier. It belongs in this section for that reason rather than because it does not work. It can work. The catch is the arithmetic.

Your clock moves roughly half an hour to three quarters of an hour a day when you push it deliberately, so a seven-hour shift is not a three-day project, it is a week of going to bed at times that make your own evenings unusable. Do it if the trip is long enough to earn it. Skip it if you are going for ten days, and put the same effort into the arrival day instead.

There is also the plan to simply stay awake for a full 24 hours and crash into the new schedule by force. It can work, but treat it as a gamble rather than a plan.

• Drinking extra water. Worth doing for comfort on a dry plane, but dehydration is not what causes jet lag.
• Strict jet lag diets that dictate exactly what to eat on which hour. Hard to follow, thin on evidence.
• Powering through on caffeine until you crash. It moves the crash, it does not cancel it.
• Sleeping pills that knock you out on the flight but leave the underlying clock exactly where it was.

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Melatonin, and what it does

Melatonin is the one supplement with evidence behind it, and even then it is a nudge, not a switch. It is the hormone your body releases as it gets dark to signal that sleep is on the way. Taken at the right time, a small dose can help shift your clock in the direction you want.

That last one on the list deserves names rather than a shrug, because this is the only page on this site recommending a hormone. Skip it, or ask first, if you have liver or kidney problems, or if you have an autoimmune condition, since melatonin can nudge the immune system in the wrong direction.

Do not give it to a child without a pediatrician saying so. And treat it as a short-term tool for the first nights of a trip rather than something you keep taking, because the long-term picture is not established.

If you try it, the common approach is a low dose, often well under what the large bottles suggest, taken close to your target local bedtime rather than whenever you happen to remember. Low means the doses actually studied run from 0.5 mg to 3 mg, and the two strongest sources disagree about which end of that works better, so the answer is the range rather than a number. Higher is not better. And because rules and reactions differ, a quick check with a pharmacist or doctor before the trip is the sensible move, especially if you take other medication.

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Before you fly and on the plane

Some of the work happens before you leave, and most of it is about setting up the arrival rather than surviving the flight itself.

Be realistic about sleep on the plane. A few hours folded into a seat is not a night's sleep, and chasing it with wine or a pill tends to leave you groggier on the other side, not fresher. Aim for rest rather than a perfect eight hours, and treat whatever you get as a bonus instead of the plan the whole trip depends on.

If you have any choice in it, the arrival time matters. Landing in the local evening lets you go more or less straight to bed and wake on the local clock. When you are comparing long-haul fares, it is worth weighing arrival time alongside price, not just chasing the cheapest possible departure.

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Sort the small frictions before you land, too. Having your data set up in advance working the moment you step off the plane means you are not solving connectivity problems with a brain running on almost no sleep.

The arrival day that decides the trip

The first day sets the tone. Handle it well and the trip starts on the local clock. Handle it badly and you spend three days chasing your own tail across time zones.

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The core moves are simple. Get outside into daylight as soon as you reasonably can. Eat your meals on local time even when you are not hungry, because food is a weaker clock cue but still a cue. Stay awake until a sensible local bedtime. Move your body a little. None of it is dramatic. All of it points your clock in the same direction at once.

That first local night is the one to protect above all others. Get to bed at a reasonable local hour even if you are not fully tired, keep the room dark and cool, and when you wake at 3am, resist checking the time. Doing the math only wakes you up further and hands you something to worry about at the worst possible moment.

The first day is not for sightseeing. It is for telling your body, in the only language it trusts, that you live here now.

A short nap on arrival is a tool. A long one is a trapdoor. You lie down for what you promise yourself is twenty minutes, and your body, sensing weakness, renegotiates this up to three hours and declines to discuss the terms. Set an alarm, or do not lie down at all. Two rules make it safe.

Keep it under half an hour, and take it at least eight hours before the local bedtime you are aiming for. Napping at four in the afternoon when you plan to sleep at ten is not a nap, it is the first third of the night, and you will pay for it at two in the morning.

Your judgment on arrival day is poor, which is worth knowing in advance. It is exactly when tired travelers accept the airport taxi at triple the rate or tap yes on a bad exchange screen. A little of the money admin is the kind of thing best decided before you land, not while foggy and looking for the exit.

Keep the first day light on purpose. No tight schedule, nothing booked that you would lose money missing if you sleep through it. A loose first day is not wasted. It is the price of a trip that works from day two onward.

It passes

The thing worth remembering at 3am, staring at a dark ceiling with your body convinced it is lunchtime, is that this is temporary. The clock resets. It usually takes about as many days as the time zones you crossed, sometimes fewer if you played the light well.

You will not beat jet lag so much as outlast it, with a few good moves that shorten the wait. And somewhere around the third morning, you wake at a normal hour, hungry at the right time, and realize you forgot to dread it. By then, the trip has already started.