How do I get over jet lag faster?

It’s 3:40am, the room is dark and a little too warm, and the city outside has gone silent. You’re completely awake, and already working out how many hours are left before the meeting, or the tour, or the morning everyone will expect you to be yourself. The hotel, or the house, is asleep around you.

At 3am here it may be early evening at home, or the middle of the morning, depending on which way you flew. Your body’s still keeping those hours. The heavy, scratchy-eyed tiredness from a short night, dry cabin air and a cramped seat is travel fatigue, and it belongs to the flight and the hours just after it. Jet lagjet lag The tiredness and broken sleep that come from crossing time zones faster than your body clock can adjust to the new local time. is what stays on in the days after you cross three or more time zones, because the body clockbody clock The timekeeper in your brain that runs on a cycle of about a day, setting when you feel sleepy and when you feel alert. Daylight, especially in the morning, keeps it in step with the clock on the wall. that times your sleep is still set to the place you left¹²1 Roach & Sargent, 20192 Morgenthaler et al., 2007. It moves toward local time a little each day³3 Arendt, 2018, and it’s already begun.

Almost every system in the body keeps its own daily rhythm, so jet lag reaches well beyond sleep, into heavy eyes by day, trouble concentrating, a shorter temper and an unsettled gut. Your appetite and the clocks in your gut and liver keep their own time. They catch up at different speeds from the clock that times your sleep, so for a few days they’re out of step with each other as well as with the clock on the wall³⁵3 Arendt, 20185 Wehrens et al., 2017. Hunger can go missing at local mealtimes. The toilet can call at hours that make no sense, and you may wake at night to pass urinenocturia Waking from sleep once or more in the night to pass urine. It’s common in both men and women, and becomes more common with age..

At the center of it is the body’s coldest, sleepiest hour, the low point in core temperature that usually comes in the early hours before waking. Nobody can feel where theirs is, but your usual sleep tells you roughly when it comes. For someone who normally sleeps from 11pm to 7am, it falls at about 4am home time. It moves an hour earlier or later for every hour earlier or later you usually sleep. Sleepiness and slips of attention are at their worst in the two or three hours either side of it¹⁴1 Roach & Sargent, 20194 Eastman & Burgess, 2009, so wherever that stretch falls in your new day is when you’ll feel foggiest. After flying from Los Angeles to London, eight hours east, that hour comes around midday local time. The late morning and early afternoon are when your eyes close mid-conversation, and bedtime comes while your body’s still in its afternoon. Going the other way, London to Los Angeles, it comes at about 8pm, and you fade through the evening and wake far too early¹.

After an overnight flight, please arrange a ride from the airport if you can. For the first few days, keep any drives away from the hours when your eyes close on their own: after a big trip east, that’s the late morning and early afternoon¹1 Roach & Sargent, 2019. A US study looked at everyday drivers in crashes, rather than travelers. Those who’d slept under four hours in the day before were about fifteen times as likely to have caused their crash as those who’d slept seven to nine. A recent change in sleep schedule was linked to causing crashes too⁶6 Tefft, 2018. A long flight tends to bring both at once: a short night and a schedule turned around.

The first night often goes better than you feared, and then the second or third comes apart. On that first night sheer lack of sleep pulls you under, whatever the clock says. That debt can largely be made up within a day. What it leaves behind is the clock, which moves far more slowly. The symptoms are worst while its low point still falls in your waking day⁴4 Eastman & Burgess, 2009. In one worked example of a trip nine hours west, from San Francisco to Beijing, the night predicted to be hardest for staying asleep was the second⁴.

For some people it runs longer still. In one small study, people flew seven hours east, took a dummy pill and had their sleep recorded night after night. Falling asleep grew harder from about the fourth night and stayed that way through the eighth. By day they were still dropping off in under ten minutes on nap tests for all ten days they were followed⁷7 Sack et al., 2007. If your fourth night is harder than your first, it was the same for the people in that study.

Flying east asks your body clock to move earlier, and flying west asks it to move later. Left to itself, the human clock runs a little longer than a day, about 24.2 hours on average. So it drifts later easily and resists being pulled earlier, which is why recovery after eastward flights takes longer¹⁴1 Roach & Sargent, 20194 Eastman & Burgess, 2009. Early measurements in travelers found the clock moving about ninety-two minutes later each day after flying west, and about fifty-seven minutes earlier each day after flying east³⁴3 Arendt, 2018.

That’s where the old rule of a day per time zone comes from, and as an average it’s about right. People vary a good deal around it, and the clock is usually quicker at the start than near the end³⁴. Perhaps a third of travelers don’t get jet lag at all³.

After a long trip east, especially eight time zones or more, the clock often goes the long way round instead. In one study, eight people flew eleven time zones east, and seven of them adjusted by moving later. Why would a clock travel nearly all the way round the world rather than take the short way back? A likely reason is the same tendency that makes east hard in the first place: a clock that drifts later easily and resists being pulled earlier may find it easier to keep sliding later than to be dragged back. In another small group flying eight zones east, one person’s clock hadn’t shifted at all after five days³⁴. These are only a handful of people, but they show how a long trip east can linger.

Light is what moves the body clock, and which way it moves depends on when the light reaches you. Light in the twelve hours or so before your body’s coldest hour pushes the clock later. Light in the twelve hours or so after it pulls the clock earlier. That’s why the same bright morning can move you toward home time after one trip and further from it after another. The effect is strongest in the three to six hours either side of that hour, and those are the hours worth planning around. Brighter, longer and bluer light makes them count for more. Through the middle of your body’s day you can live as you like, since bright light then has little effect¹⁴1 Roach & Sargent, 20194 Eastman & Burgess, 2009.

Daylight outdoors is far brighter than any room, so when you want light, being outside without sunglasses gives you the most of it. When you want to keep it away, you could stay indoors with the lights low, or wear wraparound sunglasses that let little through. Either way, those hours pass without pushing the clock the wrong way¹⁴.

You may already have tried staying up until local bedtime. It lines your sleep up with the new night, and the sleep you’ve lost helps pull you under, at least on the first night⁴. The clock itself moves more slowly, with light doing most of the steering. You can hold out until 11pm and still wake at 3am while your coldest hour is still in the local day¹⁴. So it helps to ask each day where that hour falls now. You could start from where it falls at home (about 4am, if you usually sleep 11pm to 7am) and work out what time that is where you are. From there it travels toward the local night by something like an hour a day¹³3 Arendt, 2018. As the hour moves, the windows on either side of it move too, so the light you were keeping out yesterday morning may be the light you want today.

For a stay of two days or less, the US guideline on jet lag suggests keeping your home sleep hours²2 Morgenthaler et al., 2007 rather than switching to local ones. The study behind that advice followed people on a two-day layover after flying nine hours west. Those who kept home hours were less sleepy and had less jet lag. They did face a longer stretch awake around the flight home, 37.5 hours against 30.6, and a third of them preferred living on local time so they could fit in with meals and evenings³⁷3 Arendt, 20187 Sack et al., 2007. It’s the guideline’s lowest grade of advice, based on that one study. That leaves it a choice to make around what the trip is for: the morning meeting your home clock can manage, or the dinner you came to share.

It’s easy to lie down for a quick nap in the afternoon and wake three hours later into a second wakeful night. A nap can still get you through the worst of the afternoon, and kept to about an hour it doesn’t eat into the night ahead¹⁴1 Roach & Sargent, 20194 Eastman & Burgess, 2009. If you can, it fits best in a stretch when you’d be keeping out of the light anyway. There’s more on timing in Are naps good for you?

Caffeine can take the edge off the daytime sleepiness, and the guideline lists it as an option, though it may cost you some of the night. In two small trials after a seven-hour flight east, slow-release caffeine made people measurably less sleepy by day, but they took longer to fall asleep and woke more often at night²⁷2 Morgenthaler et al., 20077 Sack et al., 2007. It reaches the clock as well: in one laboratory study, a single evening dose pushed it about three hours later³3 Arendt, 2018. Ordinary coffee hasn’t been studied in a controlled way⁷ for jet lag. If you reach for a cup, you could keep it to the earlier part of your new day, with how long caffeine stays in your system in mind.

Meals are a weaker time signal than light, and they speak mostly to the clocks in the gut and liver. You could eat at ordinary local times, which is likely to help those clocks fall in line, though there are no large trials³3 Arendt, 2018. In a laboratory study, ten young men had their meals moved five hours later. Over thirteen days the daily rhythm of their blood sugar shifted by about 5.7 hours, while the master clock stayed where it was⁵5 Wehrens et al., 2017.

The “feast and fast” anti-jet-lag diet grew from this idea, and it gives you something to do on a trip where so much is out of your hands. Its only field test, in 186 soldiers flying nine hours west, reported fewer symptoms⁷7 Sack et al., 2007. But the soldiers chose for themselves whether to follow it, no one was clearly checking and the symptoms were their own reports. Fewer of them chose it on the way home⁷, and the diet remains unproven.

Perhaps you took melatoninmelatonin A hormone your brain releases as darkness falls, telling the rest of your body that night has come. It's also sold as a tablet. from an airport pharmacy at whatever hour seemed sensible, and couldn’t tell whether it did anything. Melatonin does help when it’s taken at the right time. Researchers gathered ten trials in people flying across five or more time zones, and nine of them found it reduced jet lag. About one in every two people who took it benefited¹⁰10 Herxheimer & Petrie, 2002, probably more so the more zones they crossed, and less going west. The reviewers recommend it particularly for trips of five or more zones east¹⁰.

So why might your packet have seemed to do nothing? Melatonin is the body’s own signal that night has come, and taken as a supplement it can nudge the clock along. It makes people sleepy mainly when it’s taken during the body’s daytime¹³1 Roach & Sargent, 20193 Arendt, 2018. Taken at the wrong time, early in the day, it can cause sleepiness and slow your adjustment to local time¹⁰. The hour you took it may well be why it did so little. Timed well, it earns the American Academy of Sleep Medicine’s “Standard”, its strongest grade for jet lag²2 Morgenthaler et al., 2007.

For most adults, occasional short-term use for jet lag appears safe. If you have epilepsy or take warfarin, please ask a doctor first, because case reports suggest it may cause harm¹⁰ in both. In the US it’s sold as a supplement and isn’t regulated by the FDA as a drug². Is it okay to take melatonin every night? covers how much to take and when.

If you can spare a few evenings before flying east, shifting a little at home lets the clock start moving before you leave. In a laboratory test, twenty-six young adults moved their bedtime and waking earlier for three days, with bright light each morning, some by an hour a day and some by two. An hour a day turned out to be enough. Those people’s clocks moved nearly an hour and a half earlier. The two-hour group’s moved little further, because their faster plan outran the clock and left them struggling to fall asleep by the third night¹¹11 Eastman et al., 2005. Nobody flew anywhere, so it hasn’t been tried on a real trip, though the guideline lists it as an option that may lessen jet lag²2 Morgenthaler et al., 2007. The researchers who designed it think even one or two days are likely to help, the main cost being the evenings you miss with family and friends¹⁴1 Roach & Sargent, 20194 Eastman & Burgess, 2009. Going west, the same idea runs the other way, with bed and waking thirty to sixty minutes later each day and light in the evening, though no studies have tested it for westward trips¹⁴⁷7 Sack et al., 2007.

The flight you choose may matter too. In one case series of eighty-five people flying ten time zones east, those who arrived around midday had fewer jet lag symptoms than those who arrived in the morning, perhaps because of when they first met daylight⁷.

You’re likely to feel better well before the clock is all the way home. Once your body’s coldest hour slips inside the hours you sleep in the new place, sleep tends to come longer and better, and the daytime fog lifts a good deal. Full adjustment takes several more days¹1 Roach & Sargent, 2019. Each day you spend in the right light and the right dark brings that hour a little closer to your night. Tonight, or whatever’s left of it, the dark room is already doing its part.