Got jet lag? Try resetting your body clock

The old joke about your luggage arriving in better shape than you do after a long flight is funny only if you’re not suffering jet lag.

For years, jet lag -- that out-of-sync exhaustion that strikes after travel across too many time zones -- has befuddled and intrigued researchers. They know it’s a temporary disruption of normal circadian or body clock rhythm, but they don’t know how to prevent it.

In recent years, scientists have made some interesting advances in minimizing the effects of high-speed jet travel. Researchers have realized that jet lag is not just a problem of the brain “clock” being out of sync, as researchers believed for years, but also a disruption of other parts of the body that requires a multi-pronged approach.

Although some travelers seem more resistant to jet lag, no one’s sure exactly why or which characteristics these seemingly immune fliers share.

Traditional wisdom has it that jet lag occurs when your brain clock becomes out of step with the time at the destination. But “it’s more complicated than that,” says Gene Block, a professor of biology at the University of Virginia, Charlottesville, and a circadian rhythm researcher. Scientists know that the body clock in the brain’s hypothalamus -- which regulates body temperature, metabolism and other activities -- must resynchronize after travel across several time zones. “Only in the last few years have we discovered ‘clocks’ in other parts of the body,” he says.

Your liver and spleen have clocks, Block says. The one in the brain may be the master clock, but several other body clocks in various organs and tissues disrupt the body’s circadian rhythms too and contribute to that dragged-out feeling.

The brain must synchronize, of course, but scientists now think that the other body clocks must also re-regulate themselves to the destination time. “Different clocks take different amounts of time to resynchronize,” Block says.

Suppose you are flying from Los Angeles to Paris. “The next day, some body clocks have resynchronized to Paris time, and some have not,” Block says. You won’t feel completely normal, he says, until all the body clocks adjust to the new time zone.

Block and Michael Menaker, another University of Virginia biologist, think adjusting mealtimes to your destination before a trip can help reset your digestive system clocks. That suggestion is based on a study, published in the journal Science, in which they simulated jet lag in rats and then changed the animals’ feeding cycles.

“It might help,” says Menaker, who emphasizes that he has not studied the effects of this strategy in humans. Travelers who want to try it should begin to eat meals at the destination times starting a day or two before the trip, Menaker says. (Only do this if it’s within reason and doesn’t disrupt your normal sleeping time, Block advises.)

The mealtime adjustment makes more sense, Block says, than the so-called anti-jet lag diet, which he says has fallen out of favor with some scientists. This diet is based on eating different types of foods at different times to energize or to wind down, depending on the traveler’s schedule and activities.

The anti-jet lag diet, developed for shift workers in 1982 at the Argonne National Laboratory in Illinois, has legions of fans. It requires eating certain foods at certain times. For a copy of the diet, send a stamped, self-addressed envelope to the Anti-Jet Lag Diet, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439.

Besides readjusting mealtimes, travelers can combat jet lag by exposing themselves to natural light at their destination; by taking the hormone melatonin, which helps regulate circadian rhythms; or by using both approaches, says Dr. Al Lewy, vice chairman of the department of psychiatry at the Oregon Health and Science University, Portland, and an expert in body clock research.

When you take melatonin (available over the counter) and when you expose yourself to outdoor light depend on how far you plan to travel. Consult a physician or other professional acquainted with the approaches before trying them on yourself.

Travelers going west to east -- say, from Los Angeles to London -- might consider taking melatonin, a half-milligram or less once a day, starting a day or two before travel, Lewy says. (Even that small a dose may make you sleepy, so exercise caution if you are driving or operating machinery.) London-bound Los Angeles travelers should begin taking the melatonin at 2 p.m. Pacific time two days before travel and continue to take it at that time even on the day of travel.

Once you arrive in London, take the melatonin at 10 p.m. London time (2 p.m. Pacific time). Then move the time you take the dose two hours earlier each day until you are taking it at 2 p.m. London time, which will be in four days.

Exposing yourself to outdoor light can also help reset the body clock, but the time of exposure is crucial, Lewy says. He does not recommend that travelers going from L.A. to London get light first thing in the morning; that will reset the body clock incorrectly, he says. “Get it in the middle of the day,” he suggests. On the second day, get outdoor light first thing in the morning for about 30 minutes.

London-bound L.A. travelers who use melatonin and light exposure are advised to follow a different melatonin schedule, moving the dose three hours earlier a day instead of two hours, Lewy says.

When using melatonin for the trip home, take a half-milligram or less immediately after waking up in London, starting a day or two before returning, Lewy suggests. Take the dose on the day of travel too.

To add light exposure to the regimen, avoid outdoor light at the end of the day for the first day or two you’re home and get at least 30 minutes in the middle of the day. Then, for the next few days, try to get outdoors for 30 minutes of light at the end of the day, Lewy suggests.

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Healthy Traveler appears twice a month. Kathleen Doheny can be reached at [email protected].