Jet lag is not tiredness. That’s the thing most advice gets wrong.
It’s a mismatch between your body clock and local time. Your circadian rhythm is still running on the old timezone, telling you to sleep, eat and release hormones on a schedule that no longer matches the world outside.
Which is why sleeping on the plane doesn’t fix it, and why most of the tips you’ll read make no difference at all. Here’s what actually helps.
Why Direction Matters More Than Distance
Flying west is easier than flying east, reliably, and it’s not psychological.
The human body clock runs slightly longer than 24 hours, closer to 24.2 on average. Stretching your day is easier than compressing it, so going west, where the day gets longer, works with your body. Going east asks you to fall asleep before your body is ready.
Rough rule: recovery takes about a day per timezone crossed going east, and roughly half that going west.
So London to New York is unpleasant for a day or two. New York to London is properly rough for four or five.
What Actually Works: Light
Light is the single most powerful tool you have, and almost nobody uses it deliberately.
Your body clock resets primarily through light hitting your eyes. Get the timing right and you can shift several hours faster. Get it wrong and you can make it worse.
Flying east, you want morning light at your destination and to avoid bright light in the evening. Flying west, the opposite: get evening light, avoid bright morning light for the first day or two.
Outdoor light is many times stronger than indoor lighting, so this means actually going outside rather than sitting by a window.
The counterintuitive bit: for very large shifts of more than about eight hours, the timing flips, because you’re better off shifting the other way round the clock. Apps exist that calculate this properly.
▶ Watch This Before You Go
What Actually Works: Adjusting Before You Go
Shifting your sleep by an hour a day for two or three days before departure genuinely reduces the hit.
Going east, go to bed and get up an hour earlier each day. Going west, an hour later.
Nobody with a job and a family does this properly, and that’s fine. Even one day of partial adjustment helps a bit.
The related move that costs nothing: set your watch and phone to destination time when you board, and start thinking in that timezone immediately.
What Actually Works: Melatonin, Used Correctly
Melatonin has decent evidence behind it for jet lag, particularly eastward travel, and it’s the one supplement worth considering.
The key points people get wrong: low doses work as well as high ones, around 0.5 to 3mg, and taking more does not help. Timing matters more than dose. It’s a clock-shifting signal, not a sleeping pill.
Generally you take it in the early evening of your destination timezone for a few days after arriving east.
It’s over the counter in the US and prescription-only in much of Europe including the UK. Talk to a pharmacist or doctor, particularly if you take other medication.
What Actually Works: Meal Timing
Your digestive system has its own clock, and eating on local time helps pull it into line.
Eat at destination meal times as soon as you arrive, even if you’re not hungry, and avoid eating at three in the morning when your old timezone says lunch.
The evidence on elaborate fasting protocols is weaker than the internet suggests. Simply eating on local time is the useful part.
The Myths
Drinking lots of water cures jet lag. It doesn’t. Cabin air is dry and hydration makes you more comfortable, which is worth doing, but dehydration is not what jet lag is.
Sleeping the whole flight fixes it. It doesn’t, unless that sleep happens to line up with night at your destination. Sleeping at the wrong time can set you back.
Alcohol helps you sleep through it. It makes you drowsy and then fragments your sleep, and at altitude it hits harder. It’s the single worst thing you can do on a long flight.
Sleeping pills fix jet lag. They produce unconsciousness, not a shifted body clock. You wake up in the same mismatch, plus grogginess.
Compression socks, special diets and grounding mats. Socks are genuinely good for circulation on long flights. None of these touch your circadian rhythm :/
The First Day, Practically
Whatever time you land, get outside. Even a walk around the block does more than an hour of lying in a dark hotel room.
If you land in the morning and you’re wrecked, a nap is allowed. Twenty to thirty minutes, before 3pm local, with an alarm. Any longer and you’ll wreck that night’s sleep.
Push through to a normal local bedtime, ideally 9 or 10pm rather than 6pm. That first night is what sets the pattern.
Caffeine is fine in the morning and a mistake after about 2pm local time on the first couple of days.
Short Trips: Don’t Bother Adjusting
If you’re going for three days or fewer across a big time difference, trying to adjust is often the wrong call.
You’ll spend the whole trip half-shifted and then have to shift back. For a short business trip, staying on home time and scheduling around it can work better.
That’s a genuine strategy, not laziness, and it’s what a lot of frequent flyers do.
Common Questions
How long does jet lag last? Roughly a day per timezone travelling east, and about half that travelling west, though it varies a lot between people.
Is east or west worse? East, clearly. Your body clock naturally runs slightly long, so lengthening a day is easier than shortening one.
Does melatonin work? For eastward travel, yes, with reasonable evidence. Low dose, correct timing, and check availability and interactions where you live.
Should I nap when I arrive? A short one, under 30 minutes and before mid afternoon, is fine. Anything longer usually makes the first night worse.
Does drinking water prevent jet lag? No. It makes the flight more comfortable, which is worth doing, but it has no effect on your body clock.
