Jet lag

Jet lag is a feeling of tiredness and confusion after a long aircraft journey.

Information written and reviewed by Certified Doctors.

Contents

Introduction

Jet lag is a feeling of tiredness and confusion after a long aircraft journey. It's the result of your body finding it difficult to adjust to a new time zone. Jet lag can disturb your sleep pattern and make you feel drowsy and lethargic (lacking in energy). The more time zones you cross during a long-haul flight, the more severe jet lag can become.

Read more about the symptoms of jet lag.

What causes jet lag?

The world is divided into 24 different time zones.

Your body's natural 24-hour clock (circadian rhythm) is disrupted after crossing time zones. Your body clock controls your sleeping and waking pattern. It also affects your:

  • hunger
  • digestion
  • bowel habits
  • urine production
  • body temperature
  • blood pressure

Your body clock is set to your local time so that you feel hungry in the morning and sleepy in the evening. However, if you travel across time zones, your body clock can take a while to adjust to a new daily routine.

Read more about the causes of jet lag.

Treating jet lag

Jet lag can be a problem if you frequently fly long distances. However, it doesn't usually cause any serious or long-term health problems.

Most people find their symptoms pass after a few days without need for treatment. The advice below will help minimise the effects of jet lag.

When you arrive at your destination:

  • Establish a new routine. Eat and sleep at the correct times for your new time zone, not at the time you usually eat and sleep at home.
  • Avoid napping as soon as you arrive. Even if you are tired after a long flight, stay active until the correct time to sleep; this will help your body adjust more quickly.
  • Spend time outdoors. Natural light will help your body adjust to a new routine.

If you take medication at specific times of the day, such as oral contraceptives or insulin, speak to your doctor or pharmacist before travelling for advice.

Read more about treating jet lag.

Preventing jet lag

It is not possible to prevent jet lag but there are things you can do to reduce its effects.

Make sure you are well hydrated before flying, and drink plenty of fluid (but not alcohol) during the flight. Try to rest during the flight by taking short naps.

Read more about preventing jet lag.

Symptoms

The symptoms of jet lag can vary from person to person. The severity of your symptoms will usually depend on the distance travelled and the number of time zones crossed.

Most people only have jet lag symptoms after crossing at least three time zones. Some people may find they get mild symptoms after shorter journeys.

Sleep disturbance

A disturbed sleep pattern is one of the most common symptoms of jet lag.

You may find it difficult to sleep at the correct times. For example, you may be awake at night and sleep during the day.

Other symptoms

As well as disturbed sleep, other symptoms can include:

Symptoms will usually last for no more than a day or two, depending on how quickly your body is able to adjust to the new time zone.

Causes

Jet lag occurs when the body's normal daily routine is disrupted after crossing several different time zones.

Symptoms such as sleep disruption and tiredness are the result of your body finding it difficult to adjust to the time zone of your new location.

Circadian rhythm

Circadian rhythm is your body's natural 24-hour routine, which is controlled by "biological clocks" in your body. Jet lag occurs when your body's circadian rhythm is disrupted.

The biological clocks are found throughout your body and are made up of groups of cells that interact with each other. The cells are controlled by a "master clock" in your brain that keeps all the body clocks synchronised.

Your body is used to a regular routine of light and darkness at certain times of the day. However, when you travel to a new time zone this routine is disrupted.

Air travel makes it possible to cross several different time zones in just a few hours. Due to travelling so quickly, your body has to catch up and re-establish its circadian rhythm. It takes time for your body to adjust to new times of light, darkness and eating. It may also have to adjust to differences in temperature.

Oxygen levels

Oxygen levels in an aeroplane cabin are also thought to play a role in jet lag. The air pressure found in an aeroplane cabin is lower than normal, which means the amount of oxygen in your blood is reduced.

A reduced amount of oxygen can affect your physical and mental abilities. For example, it can make you feel lethargic (lacking in energy) and dehydrated (when the normal water content in your body is reduced).

If you have a health condition, such as heart disease, lung disease or anaemia (where red blood cells are unable to carry enough oxygen), you may be more severely affected by the reduction in oxygen inside the cabin.

East and west

Symptoms of jet lag are usually more severe when travelling east. This is because your body finds it easier to adapt to a longer day (you "gain time" travelling west) than a shorter one (you "lose time" travelling east).

Your body is able to adapt better when you travel west because you are extending your day, rather than shortening it when you travel east. Therefore, it's usually easier to delay sleep for a few hours than trying to force sleep when you're not ready to.

Increased risk

Other things that increase jet lag or increase the severity of your symptoms include:

  • dehydration (not drinking enough fluids)
  • lack of sleep
  • drinking alcohol
  • stress
  • being over the age of 60

Treatment

There are several things you can do to minimise the effects of jet lag.

When you arrive at your destination:

  • Establish a new routine and try to get used to it as soon as possible. Eat and sleep at the correct times for your new time zone, not when you usually eat and sleep at home.
  • Avoid napping as soon as you arrive at your destination. Even if you are tired after a long flight, try to stay active until the correct time to sleep; this will help your body adjust more quickly.
  • Spend time outdoors. Natural light will help your body adjust to a new routine.

If you take medication at specific times of the day, such as oral contraceptives or insulin, consult your doctor or pharmacist before travelling. They can advise you when to take your medication after you arrive at your destination.

Melatonin

Melatonin is a hormone that your body releases in the evening. It lets your brain know it is time for your body to sleep.

Your body clock is controlled by natural daylight and by the melatonin released in your body. Melatonin is produced when it gets dark to prepare your body for sleep. Your body stops producing the hormone when it gets light to help you wake up.

Some jet lag remedies contain melatonin to help you sleep at night when your body is finding it difficult to adjust to the new time zone.

However, there is currently not enough evidence to say whether melatonin supplements are effective. Some people find them helpful but they are not currently licensed to treat the prevention of jet lag.

There is also insufficient evidence regarding the possible side effects of melatonin for people taking the blood-thinning medicine warfarin, or those with epilepsy (a condition that causes repeated fits or seizures).

Speak to your doctor if you are thinking about taking a jet lag remedy that contains melatonin. They will be able to advise whether it is suitable for you.

Sleeping tablets

Some people find taking sleeping tablets can help relieve jet lag. However, they are not usually recommended because they can be very addictive if used for more than a few days.

Sleeping tablets can also cause side effects such as:

Prevention

Jet lag can't be prevented but you can take steps to reduce its effects.

Before travelling

Before you travel:

  • Change your sleep routine a few days before your departure. If you are travelling east, go to bed an hour earlier than your usual time; if you are travelling west, go to bed an hour later. Try to adapt your sleeping routine with your destination in mind.
  • Get enough sleep before you travel. Flying when you are tired can make jet lag worse.
  • Keep calm and relaxed. Airports can often be stressful places; keep calm to avoid getting stressed, as stress can make jet lag worse.
  • Check in online. This can help reduce stress and will enable you to relax as soon as you arrive at the airport.

During the flight

During the flight:

  • Drink plenty of fluids. Ensure you are well hydrated before, during and after your flight.
  • Rest during the flight. Take short naps.
  • Limit your caffeine consumption. Avoid drinking too many drinks that contain caffeine, such as coffee, tea and cola, and avoid drinking them within a few hours of planned sleep.
  • Avoid alcohol. Eat light meals and avoid drinking alcohol because it can make the symptoms of jet lag worse.
  • Keep active. When flying long distances, take regular walks around the cabin and stretch your arms and legs while you are sitting down; this will also help reduce your risk of developing a potentially serious condition called deep vein thrombosis (DVT).
  • Change your watch to match the time of your new destination. This will help you to adjust to your new time zone more quickly.

Try to get some sleep if it is night time when you arrive at your destination. You may find using ear plugs and an eye mask is useful.

Short trips

It may be better to stay on "home time" if you are only taking a short trip (less than three or four days).

If possible, arrange activities and sleep to coincide with the time at home. This will reduce the chances of your body clock being disrupted.

Content supplied by NHS Choices