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Jet Lag: How it Works and How to Deal

If you’re fortunate enough to have a big trip planned this summer, you might be worried about jet lag—a temporary sleep disorder caused by traveling across multiple time zones.

“Basically, jet lag boils down to being tired when you don’t want to be, and then not being able to sleep when you want to,” says Thomas Miller, MD, who practices at the UNC Internal Medicine Travel Clinic in Chapel Hill. He regularly sees patients planning international travel and provides relevant immunizations and medications for travel-related conditions such as malaria, hepatitis A, altitude sickness and traveler’s diarrhea.

What Happens in the Body During Jet Lag

Most people, he says, just accept that jet lag comes along with long-distance travel. But there are some steps you can take to help deal with it.

First, why does jet lag happen? It has to do with our cells. Each of our bodies is governed by a circadian clock, which keeps us in proper physiological rhythm. Specifically, there are four genes—Cryptochrome, Period, CLOCK and BMAL1—that work in unison to control the cyclical changes in human physiology, such as blood pressure, body temperature and rest-sleep cycles.

The genetic mechanisms for how the circadian clock works in the body were discovered by UNC’s own Aziz Sancar, MD, PhD, Sarah Graham Kenan Professor of Biochemistry and Biophysics and 2015 Nobel Laureate.

When we try to fast-forward or rewind the natural 24-hour day, such as when we fly six time zones away, such as between North Carolina and Paris, our circadian clocks don’t let us off easy; the genes and proteins need time to adjust. Jet lag is the feeling of our cells “realigning” to their new environment and the new starting point of a solar day.

When traveling east—say, to Europe—your body adjusts one hour per day. Going west—hello, Hawaii—it’s an hour and a half per day.

Light Exposure and Jet Lag

Dr. Miller recommends that when you arrive at your destination, you adjust to local time as quickly as possible. Being exposed to the right kind of light can help speed up your adaptation.

If you are traveling east and arriving in the morning, get out and take in some sunshine. Exposing yourself to morning light can help your body adjust more quickly. It’s OK to take a short nap if you are especially fatigued, but don’t go to the hotel and crash for hours. If you are traveling west, taking in late afternoon light and even artificial evening light will help you make the adjustment to the new time.

As you try to get used to a new sleep schedule, Dr. Miller recommends trying melatonin supplements rather than other over-the-counter sleep aids, which can leave you feeling groggy. Melatonin is a natural hormone that regulates sleep.

Above all, Dr. Miller recommends focusing on the trip itself, not the symptoms of jet lag. There’s no better medicine than enjoying your vacation.


Planning a trip and want to talk to a doctor about any necessary vaccines or medications? Find one near you.