Harvard Health Publications

Jet Lag

What Is It?

Jet lag is a type of sleep disorder that is a reaction to traveling between time zones.

Our bodies naturally develop a sleep-wake cycle that is tied to the patterns of light and dark in our environment. This cycle, called the circadian rhythm, affects many body processes, including temperature and hormone levels.

Jet Lag

Because traveling between time zones changes the light-dark patterns in your environment, it can disrupt your body's rhythms. A change of even a few hours may not seem significant, but often it is enough to affect the body's sleep-wake cycle. For example, a Californian who travels to New York may receive a wake-up call at 7 a.m., but his or her body still is running on California time, where it is only 4 a.m.

The effects of jet lag go beyond being tired for a few extra hours. Because the disruption in the sleep-wake cycle affects your body's hormone levels, many body processes can be thrown off balance, leading to a variety of symptoms.

Symptoms

Symptoms of jet lag can be mild or severe, depending on the number of time zones you cross and your sensitivity to such changes. The more time zones you cross, the more likely it is that your body rhythms will be disrupted, which can lead to more severe symptoms. Most people who cross five or more time zones will experience at least some symptoms, which can include:

  • Daytime sleepiness

  • Headaches

  • Insomnia

  • Restless sleep, possibly with frequent awakenings

  • Difficulty concentrating

  • Impaired judgment

  • Upset stomach or mild nausea

Diagnosis

There are no tests for jet lag, although the cause usually is obvious. If you have typical symptoms, you do not need to seek medical attention.

If you have symptoms of jet lag lasting longer than two weeks, it is possible that something else is triggering your sleep difficulty. Your doctor may suggest an evaluation to check for other disorders.

Expected Duration

For each time zone crossed during travel, it takes about a day to adjust to the new environment. For example, it can take up to three days for a person traveling from California to New York to feel "normal" again. If that person travels back to California after adjusting to New York time, it can take another three days to readjust to California time.

Older people seem to be hit harder by jet lag and may require a little more time to adjust. Traveling from west to east can cause more bothersome symptoms because the body has more difficulty adjusting its clock forward than backward.

Prevention

Although nothing will prevent jet lag completely, travelers can do a few things to limit its effects:

  • Before traveling, try to rearrange your home schedule to match more closely the schedule of your destination. This requires eating and sleeping at slightly different times (earlier or later, depending on your destination) than you are used to.

  • Once you arrive, try to adopt the schedule of the new location as soon as possible by sleeping at night, staying awake during the day, and eating at local mealtimes.

  • Drink plenty of water to avoid dehydration.

  • Avoid alcohol and caffeine, which can affect sleep, contribute to dehydration, and worsen jet-lag symptoms.

  • Get out in the daylight in the new time zone. Exposure to natural light may help you adapt to the new environment more quickly.

Treatment

Some people believe that the hormone melatonin helps to decrease jet lag. This hormone, which can be purchased over the counter as a supplement, is taken about 30 minutes before bed on the day of travel and for up to four days after arrival, usually at a dose of about 3 milligrams. Much smaller doses (1/2 milligram) also may work and some people need higher doses, about 5 milligrams.

Melatonin has not been studied extensively, but a few studies suggest that it can be an effective remedy for jet lag. Melatonin generally does not cause serious side effects, although there is little information on its long-term safety. Possible short-term side effects include daytime sleepiness, dizziness, headache, disorientation and loss of appetite and nausea. Some studies suggest that people with epilepsy or people taking the blood thinner warfarin (Coumadin) should avoid taking melatonin supplements. Melatonin is considered a nutritional supplement, and therefore it is not closely regulated. If you want to consider using melatonin to treat jet lag, talk with your doctor first.

Prescription sleeping medications, such as zolpidem (Ambien) or a related group of drugs called benzodiazepines, may be effective for jet lag. This is particularly true for people who have difficulty falling asleep after traveling to a new time zone.

When To Call A Professional

Usually, it is not necessary to call a doctor to treat jet lag. However, you should call a health care professional if symptoms have not cleared up within two weeks.

Prognosis

Jet lag is a mild problem that goes away on its own within several days. People with regular routines and older people may have less ability to tolerate shifts in their light-dark cycles and may take slightly longer to recover. However, even for these people, all symptoms should disappear within two weeks.

Learn more about Jet Lag

External resources

International Society of Travel Medicine
P.O. Box 871089
Stone Mountain, GA 30087-0028
Phone: (770) 736-7060
Fax: (770) 736-6732
http://www.istm.org


Disclaimer: This content should not be considered complete and should not be used in place of a call or visit to a health professional. Use of this content is subject to specific Terms of Use & Medical Disclaimers.

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