Jet lag is a common condition that sometimes occurs after long distance flights. It is 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). Jet lag often becomes more severe as more time zones are crossed.
Time zones
The world is divided into 24 time zones. The Greenwich meridian (an imaginary line that passes through Greenwich, in London, and is used to help measure longitude) is the base. The time changes by one hour for every 15 degrees travelled in either direction from the Greenwich meridian.
Jet lag occurs after crossing a number of time zones, which disrupts the body's normal ‘circadian rhythm’ (your body's natural 24 hour routine). The ‘biological clock’, or ‘body clock’, controls when you need to sleep and when you are awake.
It also affects:
- hunger
- digestion
- bowel habits
- urine production
- body temperature
- blood pressure
Your biological clock is usually synchronised with your local time so that you feel hungry in the morning and sleepy in the evening. However, after travelling across time zones, your body takes a while to adjust to a new daily routine.
See Jet lag - causes for more information about circadian rhythm and the biological clock.
Who gets jet lag?
Anyone can get jet lag, regardless of how often they travel by plane. People of any age can develop jet lag, but it is more common in people who are over 60 years of age.
Jet lag is thought to be less common in children and babies. However, there is no clear evidence available to enable an estimate to be made of how many children and babies are affected.
Outlook
If you have had jet lag before when travelling, you are more likely to get it again in the future. However, jet lag is not always inevitable upon flying long distances, and there are ways to help prevent the condition occurring.
See Jet lag - prevention for more information about how to cope with jet lag, and ways of preventing the condition.
Jet lag may prove problematic for people who have to fly frequently, or those travelling to important meetings, or events. However, it does not cause any serious or long-term health problems.
Most people find that their jet lag symptoms pass within a few days without the need for treatment.