International travelers know the feeling as they stumble through the airport at their destination: dragged out and fuzzy-brained with a churning stomach.
It's just another case of jet lag. There's no way to avoid it, and there's no instant cure, but there are several things you can do to limit its effects.
"Jet lag occurs when your body's internal clock is set to a different time than your environment," Dr. Daniel Lieberman, a psychiatrist at the Clinical Psychiatric Research Center at the George Washington University Medical Center in Washington, D.C., explains. "When the local clocks tell you it's the middle of the day, your body has entered its sleep phase. Your temperature starts to fall, your metabolism slows down and you may begin to experience the symptoms of jet lag."
Symptoms and duration are highly individualized but may include daytime fatigue, restless sleep, insomnia, nausea and lack of focus. You may be grumpy and may have difficulty concentrating and eating. Some people stumble as if they were a little tipsy. In general, figure that you'll need one day for each time zone crossed to recover from jet lag.
For most travelers, jet lag occurs when traveling east to west or west to east. But for many, it's easier to travel east to west because you feel as if you're gaining time, compared with flying west to east, when you feel like you're losing time.
Even a traveler to New York from San Francisco may feel the three-hour difference the day after arrival. A 6 a.m. wake-up call at a hotel in New York is 3 a.m. in San Francisco. The time difference between San Francisco and London is eight hours; New York and Paris, six hours; New York and Tokyo, 11 hours.
If you work at Microsoft's Washington State headquarters and have a meeting with Lucent at its New Jersey campus, you'll cross three time zones and may need three days to be in top shape.
In general, jet lag isn't a severe problem for north-south flights that don't span several time zones.
Some travelers take melatonin, a hormone, to reduce the effect of jet lag. However, its effectiveness hasn't been extensively studied. Those who use it generally take a five-milligram dose about half an hour before going to bed on the day before departure and for several days after arrival. Melatonin can be purchased over the counter at most drug or health food stores.
Other travelers try to adjust the body clock with an anti-jet lag diet developed by . The idea is to alternate days of chowing down on high-protein breakfasts and lunches and high-carbohydrate dinners with light, low-calorie meals. Carbohydrates make it easier to sleep, and fasting limits the body's store of carbohydrates, making it easier to reset your internal clock. In theory, this helps your body adjust to a new time zone. Most travelers start the diet three days before departure.
The only sure-fire method to overcome jet lag is to arrive several days before your business meeting and ease into the new time zone. Take it easy — walk around, get some sun, go to a museum, see the sights — and you'll be sharp when you open your briefcase and get down to brass tacks.
"Jet lag is more than just uncomfortable and inconvenient," Lieberman says. "It can take away the pleasure of an expensive overseas vacation or have a negative effect on the outcome of an important overseas business negotiation. It can even make a person forgetful and accident prone."