Jet lag can't be fully prevented, but you can make it shorter and milder. What actually works: shift your sleep towards your destination's time before you leave, drink water and go easy on caffeine and alcohol on the plane, switch to local time as soon as you land, get outside in daylight and avoid sleeping during the day. The NHS says jet lag usually improves within a few days as your body adjusts. Below you'll find what to do before, during and after your flight, how to handle jet lag insomnia and what health bodies say about melatonin.
What Causes Jet Lag?
Your body runs on a roughly 24-hour internal clock called the circadian rhythm. It tells you when to sleep and when to wake, and cues such as sunrise and sunset keep it set (MedlinePlus). The master clock sits in your brain, in a group of nerve cells called the suprachiasmatic nucleus (SCN). It controls how much melatonin, the hormone that makes you sleepy, your body makes, based on how much light your eyes receive (NIGMS).
When you fly across several time zones, that clock stays on home time while the sun follows local time. The more time zones you cross, the worse jet lag can be, and flying east is usually harder to adjust to because you lose time (MedlinePlus).
Symptoms of jet lag
The NHS lists these as the main symptoms (NHS):
- difficulty sleeping at bedtime and waking up in the morning
- tiredness and exhaustion
- difficulty staying awake during the day
- poor sleep quality
- concentration and memory problems
Jet lag can also cause indigestion, nausea, constipation, changes in appetite and mild anxiety.
How Long Does Jet Lag Last?
The NHS says jet lag usually improves within a few days. The US National Heart, Lung, and Blood Institute (NHLBI) says your body adjusts to 1 to 1.5 time zones per day (NHLBI). So if you cross six time zones, expect around four to six days before you feel fully on local time. That's why it pays to arrive a few days early if you have an important event or meeting. If the trip itself leaves you drained, see how to deal with travel burnout, including signs, rest and recovery.
Before You Fly
Shift your sleep a few days ahead
Get plenty of rest before you travel. The NHS suggests going to bed and getting up earlier or later than usual, closer to the time zone you're travelling to (NHS). MedlinePlus gives the direction:
- Flying east: go to bed earlier for a couple of nights before you leave.
- Flying west: go to bed later for a couple of nights before you leave.
The NHLBI adds that you can start a few days before the trip and use bright light to help move your waking time earlier or later (NHLBI).
Plan your arrival
If you're travelling for an important event, get there early so your body can adjust first, and try not to make any important decisions on your first day (MedlinePlus). If you have a stopover, MedlinePlus suggests making yourself comfortable and getting some rest. Our guide to direct vs layover flights helps you choose.
Sort your phone at home
Arriving tired is the worst time to hunt for Wi-Fi or a phone shop. If you install an eSIM before you fly, it connects when you land, so you can message home, open maps and find your hotel straight away. Follow our eSIM installation guide and check your phone in the list of eSIM compatible devices.
During the Flight
The NHS advice for the flight itself is simple (NHS):
- Drink plenty of water.
- Keep active by stretching and regularly walking around the cabin.
- Sleep if it's night time at your destination, and use an eye mask and earplugs if they help.
- Don't drink too much caffeine or alcohol, because they can make jet lag worse.
MedlinePlus adds two tips: set your watch to the new time as you begin the trip, and avoid heavy meals on board. It also says not to sleep unless it matches bedtime at your destination. For more on staying well in the air, read our tips for staying healthy on long-haul flights, and check how airplane mode works before you board.
After You Arrive
Switch to local time straight away
The NHS recommends you change your sleep schedule to the new time zone as quickly as possible, set an alarm so you don't oversleep in the morning, and only sleep at night, not during the day (NHS). Staying awake until a normal local bedtime is hard on day one, but it's what resets your clock fastest.
Use daylight at the right time
Go outside during the day, because natural light helps your body clock adjust (NHS). Light is the strongest signal for resetting your sleep-wake cycle, and timing matters (NHLBI):
- After flying east: get bright light in the morning, which moves your sleep and wake times earlier.
- After flying west: get bright light in the late afternoon or early evening, which moves them later.
In the evening, keep the lights dim and cut down on light from screens. The NHLBI says artificial light can lower your melatonin levels and make it harder to fall asleep, and that light-blocking glasses, screen filters or apps can help.
Keep moving, but not late
Stick with your normal exercise routine while you're away, but avoid exercising late in the evening, because it can keep you awake (MedlinePlus). A walk outside in the morning gives you exercise and daylight at the same time. Feeling unsettled in a new place? See how to handle culture shock when traveling abroad.
Jet Lag Insomnia: What to Do When You Can't Sleep
Lying awake at 3am or fighting to stay awake in the afternoon are classic jet lag problems. The NHS lists jet lag as one of the common causes of insomnia, and its sleep advice helps here too (NHS):
- Get up at the same time every day, and don't sleep in after a bad night.
- Relax for at least an hour before bed, for example with a bath or a book.
- Make your room dark and quiet. Use curtains, an eye mask or earplugs if needed.
- Don't drink alcohol, tea or coffee in the 6 hours before bed.
- Don't eat a big meal late at night.
- Don't use your phone or watch TV right before bed, because the blue light makes you more awake.
- Don't nap during the day, and don't drive when you feel sleepy.
What about sleeping tablets?
The NHS says medicines are not usually needed for jet lag. Sleeping tablets may help if you have problems sleeping, but they can be addictive, so they're only for a short time and if symptoms are severe (NHS). Sleep aids you can buy at a pharmacy may help for 1 to 2 weeks but should not be taken for longer, and some can make you drowsy (NHS). Check with a doctor before you take anything.
Does Melatonin Help With Jet Lag?
Health bodies don't fully agree, so talk to a doctor or pharmacist before you try it.
- UK: the NHS says melatonin tablets are not recommended on the NHS for jet lag because there's not enough evidence that they work (NHS). In the UK, melatonin is only available with a prescription (NHS).
- US: the National Center for Complementary and Integrative Health (NCCIH) says research suggests melatonin supplements may help with jet lag, based on reviews of small studies of eastward and westward flights (NCCIH).
The NCCIH also notes that in the US melatonin is a dietary supplement, regulated less strictly than medicines, and that tests have found the amount in some products doesn't match the label. In several other countries it's prescription-only. People with epilepsy or taking blood thinners should only use it under medical supervision, and the NHS says melatonin can make you sleepy, so don't drive after taking it.
Short Trip? Stay on Home Time
If your trip is only 2 to 3 days, the NHS says you could try keeping your usual eating and sleeping times instead of switching, so you don't have to change your schedule again when you get back (NHS). On longer trips, switch to local time as soon as you can.
Land Connected, Not Stressed
When you're jet lagged, small tasks feel big. An eSIM installed at home connects to a local network when you land, so you can order a ride, check your hotel booking and tell family you've arrived without looking for Wi-Fi. Our tips on how to stay connected while travelling cover the other options.
Flying to the USA? These data-only plans work across the country:
Data-only plans for the USA · 10 GB, 20 GB or 50 GB · See all USA eSIMs · Compare them in our guide to the best eSIM for the USA
Flying to Europe? One plan covers many countries on the same trip:
Data-only plans for Europe · 10 GB, 20 GB or 50 GB · See all Europe eSIMs · Heading somewhere else? Find your destination
FAQs
Can you prevent jet lag completely?
No. The NHS says jet lag cannot be prevented, but shifting your sleep before you go, drinking water, limiting caffeine and alcohol and getting daylight at your destination can reduce its effects.
How long does jet lag last?
The NHS says it usually improves within a few days. The NHLBI says your body adjusts to 1 to 1.5 time zones per day.
Is jet lag worse flying east or west?
East is usually harder, according to MedlinePlus, because you lose time.
How do I overcome jet lag insomnia?
Get up at the same time every day, get daylight in the daytime, keep your room dark and quiet, avoid caffeine and alcohol in the 6 hours before bed and don't nap during the day. If it doesn't improve, speak to a doctor.
What if I can't stay awake during the day?
Go outside and keep moving, because daylight helps your body clock adjust. The NHS advises against sleeping during the day, so try to hold on until a normal local bedtime.
Should I take melatonin for jet lag?
Ask a doctor or pharmacist first. The NHS doesn't recommend it for jet lag because of a lack of evidence, while the US NCCIH says it may help. Rules on buying it differ by country.
Should I change my sleep on a short trip?
For trips of 2 to 3 days, the NHS says you could keep your home eating and sleeping times.
