Jet lag: symptoms, how long it lasts and how to treat it

Jet lag is a short-term sleep problem that happens when you travel quickly across time zones. Patient.info explains that the body has a natural 24-hour rhythm (the circadian rhythm), and jet lag results from a temporary mismatch between your internal clock and the sleep and wake schedule at your destination. This can make it hard to fall asleep or make you sleepy when you are trying to stay awake.

Patient.info says it does not need a flight to happen: shift work or a series of late nights can have the same effect. It only affects people travelling quickly, because if you travel more slowly, by boat or car, the body clock can adjust gradually.

The NHS lists the main symptoms below. It adds that jet lag can also sometimes cause indigestion, feeling sick (nausea), constipation, changes in appetite and mild anxiety.

Patient.info lists a wider set, including feeling light-headed or "spaced out", jitteriness, irritability, low mood, poorer coordination, and worse sports performance. It says that changes in cabin pressure can cause dehydration and bloating, which may add to symptoms.

• Difficulty sleeping at bedtime and waking up in the morning (NHS).

• Tiredness and exhaustion (NHS).

• Difficulty staying awake during the day (NHS).

• Poor sleep quality (NHS).

• Concentration and memory problems (NHS).

• Indigestion, nausea, constipation, changes in appetite and mild anxiety (NHS).

The NHS says jet lag usually improves within a few days as your body adjusts to the new time zone. Patient.info is more specific: the body clock can adjust by 1 to 2 hours a day without much difficulty, but adjusting by more than 3 hours takes time, roughly a day for each hour of adjustment. Three hours is borderline, as some people will notice it and others will not.

Patient.info also says people vary. There is a small subgroup of people whose adjustment is very slow to begin, and who may do better starting preparation 4 to 5 days before travel instead of 2 to 3. If you are not recovering and symptoms are causing problems, see a doctor.

The NHS says medicines are not usually needed for jet lag, which often improves after a few days as your body clock adjusts. It says sleeping tablets may be helpful if you are having problems sleeping, but they can be addictive so should only be used for a short time and if symptoms are severe.

On melatonin, the NHS jet lag page says melatonin tablets are not recommended on the NHS for jet lag because there is not enough evidence to show they work. The NHS melatonin page says melatonin can be taken as a short-term treatment for jet lag in adults, that there is some evidence it makes symptoms less severe and may reduce recovery time by a day to a day and a half, and that melatonin for jet lag may not be available on NHS prescription. The usual dose it gives is one 3 mg tablet at your normal bedtime at your destination, not earlier than 8pm and not later than 4am, for up to 5 nights in a row.

The NHS also says melatonin supplements are not authorised for sale in the UK and are prescription-only, and that ordering melatonin online is not recommended. Speak to a pharmacist or doctor before taking melatonin or sleeping tablets, especially if you drink alcohol or take other medicines that make you sleepy.

The NHS says jet lag cannot be prevented, but there are things you can do to reduce its effects. Patient.info says it is possible to avoid jet lag but it needs commitment and advance planning, shifting your sleep period 2 to 3 days before travel (4 to 5 if you are a slow adjuster).

• Before you travel: get plenty of rest, and you could start going to bed and getting up earlier or later than usual, more like the time zone you are travelling to (NHS).

• During the flight: drink plenty of water, keep active by stretching and walking around the cabin, try to sleep if it is night time at your destination, and use an eye mask and earplugs if they help (NHS).

• During the flight: do not drink too much caffeine or alcohol, as they can make jet lag worse (NHS).

• After you arrive: change your sleep schedule to the new time zone as quickly as possible and set an alarm to avoid oversleeping (NHS).

• After you arrive: go outside during the day, because natural light helps your body clock adjust (NHS).

• After you arrive: do not sleep during the day, only at night (NHS).

• Short trips of 2 to 3 days: you could try not changing your eating and sleeping times to the new time zone (NHS).

Patient.info says some of the symptoms of jet lag, such as poor concentration or feeling spaced out, may cause problems performing complex or potentially dangerous tasks such as driving or operating machinery, and that you should not drive if you feel you are not functioning normally. It also notes that jet lag may cloud business travellers' thinking for several days.

Patient.info says people who travel frequently, particularly airline pilots and crew, are most likely to have problems, and most people who fly very long distances will be affected, particularly if they cannot sleep on the flight. It says people differ in how quickly they adjust.

The sources reviewed for this guide do not give separate advice for children or for pregnancy. If you are pregnant, have a medical condition or take regular medicines, check with your GP or pharmacist before using sleeping tablets or melatonin.

Patient.info says to see your doctor if you are not recovering from jet lag and your symptoms are causing problems, such as sleep disturbance, disrupted appetite or altered mood including anxiety and depression. A doctor can assess your symptoms and suggest how to manage them.