Jet lag refers to disturbed sleep patterns, weakness and disorientation caused by travelling. It happens when your normal body clock is disrupted by travelling through several time zones.
Jet lag is worse when you move from west to east because the body finds it harder to adapt to a shorter day than a longer one.
GP Dr Dawn Harper explains: "Our body clock is primed to respond to a regular rhythm of daylight and darkness. It is thrown out of sync when it experiences daylight at what it considers the wrong time, and it can take several days to readjust."
Before you travel
Top up your sleep
Make sure you're fully rested before you travel. If you're flying overnight and you can get a bit of sleep on the flight, it will help you to stay up until night time once you arrive at your destination.
Change your sleep routine
A few days before you travel, start getting up and going to bed earlier (if you're travelling east) or later (if you're travelling west). During the flight, try to eat and sleep according to your destination's local time.
Have a stopover on the way
Including a stopover in your flight will make it easier to adjust to the time change, and you'll be less tired when you arrive. Take advantage of any short airport transits to have a refreshing shower or swim in the terminal, if possible.
During your journey
Dehydration can intensify the effects of jet lag, especially after sitting in a dry aeroplane cabin for many hours. Avoid alcoholic and caffeine drinks (such as coffee, tea and cola), which can disturb sleep.
Preparing for sleep
During your flight, try to create the right conditions when preparing for sleep. Eyeshades and earplugs may help you sleep. Regular exercise during the day may also help you sleep, but avoid strenuous exercise immediately before bedtime.
Use remedies with caution
Many airline staff take melatonin, a hormone formed by the body at night or in darkness, to try to fight jet lag. Sleeping medication is not recommended as it doesn't help your body to adjust naturally to a new sleeping pattern.
At your destination
Try to get as much sleep in every 24 hours as you normally would. A minimum block of four hours' sleep during the local night - known as "anchor sleep" - is thought to be necessary to help you adapt to a new time zone. If possible, make up the total sleep time by taking naps during the day.
The cycle of light and dark is one of the most important factors in setting the body's internal clock. Exposure to daylight at the destination will usually help you adapt to the new time zone faster.
For stays of less than three or four days, it may be better for the traveller to remain on "home time" (that is, timing activities such as sleeping and eating to occur at the times they would have occurred at home) to minimize disruption to the normal sleep-wake cycle although this is not always practical.
Article provided by NHS Choices