Definition Jet lag is a condition in which a person's normal sleep cycle is disturbed by travel across time zones.
What is going on in the body? A person who travels between different time zones needs time for his or her internal body clock to reset itself and adjust to the new time zone. The body usually develops a set pattern of times when it is used to eating, sleeping, working, and performing other activities. Jet lag occurs because the body is reacting to a change in the schedule of normal activities.
What are the signs and symptoms of the condition? The common symptoms of jet lag include:
What are the causes and risks of the condition? The primary cause of jet lag is crossing time zones and then trying to get the body to react and adjust right away. Flying north or south does not cause jet lag. The more time zones crossed, the more difficult it is for the body to adjust to the new time zone. The body can generally adjust to a time change of about 1 or 2 hours per day. After travel across three time zones, which often occurs in a trip from the west to the east coast, the body may need up to 3 days to adjust to the new time.
What can be done to prevent the condition? Some measures may help prevent or lessen the severity of jet lag. These include:
adjusting the body's internal clock in advance. For instance, people can start adjusting their daily schedules to match the time zones they will travel to before travel takes place. People can set their watches to the new times a day before travel, and begin eating, sleeping, and working as if they were already there.
eating light and drinking plenty of fluids. Before the flight, a high-protein, low-kilojoule meal is advised. The amount of salty and fatty foods eaten should be limited. Dry air during the flight can cause dehydration, so people are advised to drink plenty of non-alcoholic fluids. Water is best, and many experienced travellers bring their own bottles of water with them.
exercising frequently. Even getting up periodically and walking up and down the aisles of the plane can help, which may be the only exercise possible. Sitting in a cramped airplane seat for an extended time is uncomfortable for everyone. During a stopover, people may want to take a few minutes and leave the plane to go for a brisk walk around the terminal, if possible.
getting enough sleep. People may want to try sleeping on the plane or plan to arrive at their destinations in time to catch a nap before starting activities. Mild sedatives may help some people get sleep during travel.
How is the condition diagnosed? Most people will recognise when they have jet lag. The fatigue, drowsiness, irritability, and other symptoms will be clear to someone who has just traveled between different time zones.
What are the long-term effects of the condition? There are no long term effects.
What are the risks to others? The only risk to others is when a person who is suffering from jet lag becomes unpleasant and uncomfortable to be around. Jet lag is not contagious.
What are the treatments for the condition? There are no medical treatments for jet lag. Time will make jet lag disappear. When multiple time zones are crossed, such as in overseas travel, some people may want to use a mild sedative, sleeping pill, or melatonin to help "reset" their internal body clocks and get enough sleep.
What are the side effects of the treatments? Sedatives, such as diazepam, and sleeping pills, such as temazepam, may cause prolonged sleepiness and may impair co-ordination.
What happens after treatment for the condition? People gradually adjust to the new time zones and need no further treatment.
How is the condition monitored? People can monitor their own symptoms of jet lag.
Author: John Riddle Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
