The short answer
Jet lag happens when your body clock is out of step with the time at your destination after a long flight. It usually improves within a few days. To recover faster, switch to local time quickly, get daylight during the day and avoid napping. Melatonin reduced jet lag in most trials, though the NHS doesn't recommend it because it judges the evidence too limited.
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Why does jet lag happen?
Your body clock runs on a roughly 24-hour cycle and is reset each day, mainly by light. It shifts only gradually, so after crossing several time zones it’s still set to home time. You feel sleepy in the afternoon, wide awake at night and hungry at odd hours. Jet lag can also cause poor concentration, indigestion, constipation, feeling sick and low mood.
How can you reduce it?
Before you travel
- Get plenty of rest beforehand.
- For a big time difference, start shifting your bedtime and waking time towards the destination time zone a few days ahead, by an hour or so a day.
During the flight
- Drink plenty of water and go easy on caffeine and alcohol, which can make jet lag worse.
- Sleep if it’s night at your destination, using an eye mask and earplugs.
- Stretch and walk around the cabin.
After you arrive
- Switch to local time straight away for meals and sleep.
- Get outside in daylight during the day.
- Avoid napping, or keep naps short, and set an alarm so you don’t oversleep in the morning.
Does light timing matter?
Yes. Light in the morning moves the body clock earlier, and light in the evening moves it later. After flying east, morning daylight helps. After flying west, afternoon and evening daylight helps. For very large time differences the best time for light shifts over the first few days, which is what jet lag apps calculate.
What about short trips?
For a trip of 2 or 3 days, the NHS suggests you could keep to home time for eating and sleeping rather than adjusting and then readjusting when you get back.
What about melatonin and sleeping pills?
The NHS doesn’t recommend melatonin for jet lag, saying there isn’t enough evidence, and it’s prescription only in the UK. However, a 2002 Cochrane review found that in 9 of 10 trials, melatonin taken close to the target bedtime at the destination reduced jet lag after flights crossing five or more time zones. See our guide to melatonin.
The NHS says sleeping tablets may help if you can’t sleep, but they can be addictive, so should only be used for a short time and if symptoms are severe.
Keep reading
- When to see a GP about sleep problems
The signs that a sleep problem needs a doctor, what to take to your appointment, what a GP can offer, and when to get urgent help.
- Insomnia: causes, self-help and treatment in the UK
What insomnia is, why it becomes long-term, what you can do yourself, and what the NHS offers, from CBT for insomnia to short courses of sleeping pills.
- CBT for insomnia: how it works and how to get it on the NHS
What CBT for insomnia involves, including sleep restriction and stimulus control, how well it works in trials, and how to get it through the NHS or an app.
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Common questions
Is jet lag worse flying east or west?
Usually east. Flying east means you need to fall asleep earlier than your body clock wants, and most people's clocks find it easier to run later than earlier. Flying west, you stay up later, which is easier.
How long does jet lag last?
The NHS says it usually improves within a few days as your body adjusts. The more time zones you cross, the longer it tends to take.
Can I take melatonin for jet lag?
Melatonin is prescription only in the UK, and the NHS doesn't recommend it for jet lag. A Cochrane review found it reduced jet lag in 9 of 10 trials when taken near bedtime at the destination. Some travellers obtain it on private prescription. Don't take it with alcohol, and don't combine it with sleeping pills.
Should I stay awake on the plane?
Try to sleep if it's night-time at your destination and stay awake if it's daytime there. An eye mask and earplugs help.
References
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.