Jet Lag: Symptoms, Causes and How to Recover

Jet Lag: Symptoms, Causes and How to Recover

What jet lag is, why it happens, the symptoms to expect and what helps you adjust to a new time zone.

What is jet lag?

Jet lag is a short-term sleep problem that happens when you fly across time zones faster than your body clock can adjust. Your internal clock (circadian rhythm) controls when you feel sleepy and alert, when you get hungry and even your digestion. After a long-haul flight it is still running on the time back home, so it no longer matches daylight and mealtimes at your destination.

Doctors class it as a circadian rhythm sleep disorder. It can start after crossing just 2 time zones, and it usually becomes noticeable after 3 or more. North to south flights, such as the UK to South Africa, don't cause jet lag, although the long journey can still leave you tired.

What causes jet lag?

Your body clock sits in a small area of the brain called the suprachiasmatic nucleus. It runs on a cycle of roughly 24 hours and is kept on time mainly by light hitting your eyes, and to a lesser extent by meals, activity and social routine. In the evening, as light fades, your brain releases the hormone melatonin, which signals that night is coming.

When you land in a new time zone, daylight, mealtimes and everyone around you are on local time, but your body clock is still on home time. It can only shift by about an hour or so a day, so for several days your body wants to sleep, eat and wake at the wrong times. That mismatch is jet lag.

What makes jet lag worse

• Crossing more time zones.
• Flying east, which shortens your day. See why jet lag is worse flying east.
• Arriving short of sleep, after a late night packing or an overnight flight with little sleep.
• Alcohol and caffeine on the flight or soon after arriving.
• Staying indoors after arrival, which deprives your body clock of daylight.
• Having had bad jet lag before: some people are simply more sensitive to it.

Symptoms of jet lag

Symptoms usually start within a day or two of arriving and are mainly about sleep:

• Trouble sleeping at night: struggling to fall asleep, or waking in the early hours and not getting back to sleep.
• Sleepiness during the day, often at the time it would be night back home.
• Tiredness and exhaustion that a single night's sleep doesn't fix.
• Poor concentration and memory, sometimes described as brain fog.
• Irritability and low mood.
• Stomach problems: indigestion, bloating, constipation or diarrhoea, and feeling hungry at odd times.
• Feeling generally unwell or headachy.

Jet lag or travel fatigue?

Any long journey can leave you tired, stiff and dehydrated. That's travel fatigue, and it usually clears after a good night's sleep. Jet lag lasts longer because the problem is your body clock, not just the journey. If you're still struggling to sleep at night and fighting sleep during the day several days after arriving, it's jet lag.

How long does jet lag last?

Usually a few days to a week. Your body clock adjusts by about 1 hour a day after flying east and about 1.5 hours a day after flying west, so the more time zones you cross, the longer it takes. Our guide how long does jet lag last? has recovery times for popular destinations and explains why some people take longer.

How to recover from jet lag

The aim is to move your body clock onto local time as quickly as possible. The most effective things you can do are:

• Switch to local time straight away: eat and sleep at local times from the day you land.
• Get daylight at the right time of day: it's the strongest signal to your body clock.
• Keep naps short: 20 to 30 minutes, and not late in the afternoon.
• Go easy on alcohol, and avoid caffeine in the evening.
• On short trips of 2 or 3 days, consider staying on home time instead.

Our guide how to get over jet lag explains each step in detail, including what to do when you can't sleep. To reduce jet lag before it starts, see how to prevent jet lag.

Jet lag in children and older adults

Children get jet lag too, though many adjust faster than adults. The same steps help: daylight, meals and bedtimes on local time, and short naps only. Melatonin for jet lag isn't licensed for under-18s, so don't give children melatonin unless a doctor has advised it.

Older adults may find jet lag takes longer to settle and may be more affected by broken sleep. Be cautious with any medicine that causes drowsiness, especially at night, because of the risk of falls.

Can medication help with jet lag?

Most jet lag gets better without medicine, and NHS advice is that medicines usually aren't needed. If jet lag badly affects you, or you travel often across many time zones, these options may help:

• Melatonin: in the UK, melatonin 3mg tablets are a prescription-only medicine, licensed for the short-term treatment of jet lag in adults. They're taken at bedtime after you arrive, for up to 5 days. The NHS doesn't recommend melatonin supplements for jet lag, but a Cochrane review found melatonin reduced jet lag in most trials of flights across 5 or more time zones. Our melatonin for jet lag guide explains the evidence and how it's used.
• Sleeping tablets: a doctor may prescribe a short course for severe sleeplessness, but they can cause next-day drowsiness and dependence. Sedating antihistamines bought from a pharmacy aren't recommended for jet lag.
• Caffeine: coffee or tea during the local day can help you stay alert. Avoid it later in the day.

Melatonin isn't sold over the counter in the UK: see can you buy melatonin over the counter?.

When to get medical help

• Call 999 if you have chest pain, sudden breathlessness or cough up blood during or after a flight. These can be signs of a blood clot in the lungs.
• Call NHS 111 or see a GP urgently if one calf or thigh becomes painful, swollen, warm or red after a long flight, which could be a deep vein thrombosis (DVT).
• See a GP if you get a fever after travelling to a country with malaria, even weeks later. See our malaria tablets page before you go.
• See a GP if you're very confused, or if poor sleep or exhaustion lasts more than 2 weeks after you get home.

Getting jet lag treatment

If you're an adult with a long-haul trip coming up, our prescribers can assess you online for licensed melatonin 3mg tablets. See our jet lag treatment page for who it's suitable for and how the service works. Prone to car or sea sickness? See our travel sickness tablets.

UK safety and reporting side effects

In the UK, melatonin is a prescription-only medicine. Melatonin 3mg tablets are licensed for the short-term treatment of jet lag in adults aged 18 and over, and they aren't licensed for jet lag in children. Before any medicine is supplied, a GPhC-registered pharmacist independent prescriber reviews your consultation, including your health and the other medicines you take. Always read the patient information leaflet in the pack.

Melatonin sold as a supplement abroad or on unregulated websites (as gummies, sprays or tablets) isn't a licensed medicine in the UK, and its strength and contents can vary. Only buy medicines from a registered UK pharmacy: you can check any online pharmacy on the GPhC register.

If you think you've had a side effect from a medicine, tell your pharmacist or doctor. You can also report it to the MHRA through the Yellow Card scheme, which helps keep medicines safe for everyone.

Jet lag is only one part of travel health. Before you go, check FCDO travel advice for your destination and TravelHealthPro for vaccines and malaria advice. Tiredness after a long-haul flight affects your reactions, so don't drive if you feel sleepy after you land.