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.
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:
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.
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:
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.
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.
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.
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.
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.
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 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 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.
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.
Other things that increase jet lag or increase the severity of your symptoms include:
There are several things you can do to minimise the effects of jet lag.
When you arrive at your destination:
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 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.
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:
Jet lag can't be prevented but you can take steps to reduce its effects.
Before you travel:
During the flight:
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.
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.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.