Related topics: •  Travel Health

Jet lag is an unfortunate by-product of the era of rapid air travel. Your body has a 24-hour biological clock that controls your daily cycles of sleeping, eating, and many other functions, which are known as circadian rhythms. When you travel across several time zones, your day becomes longer or shorter than 24 hours, disrupting your normal body rhythms. If you've just flown from Seattle to Paris, for example, you may be wide awake and ravenous at 2 am. That's because your body is still on Seattle time and hasn't had a chance to acclimate.

Fatigue, insomnia, headaches, light-headedness, and gastrointestinal upsets such as diarrhea and constipation are the most common ones. You may also feel disoriented and have trouble with decision-making and short-term memory. For example, you may end up returning to your hotel room three times because you can't remember locking the door. NASA estimates that for each time zone you cross, you need about a day to fully adjust.

The more time zones you cross, the greater your chances of becoming jet lagged. Also, traveling east is generally tougher because the regular 24-hour day is shortened and bedtime arrives earlier. Trying to sleep before your internal clock says you are ready can be frustrating, and getting up for breakfast in the morning is even harder. Traveling west, you get a longer day, and you have to stay up later and sleep later, which is generally easier to do.

If you travel across several time zones frequently, you'll probably suffer some degree of jet lag, and you won't be alone. Jet lag has caused many a diplomatic blunder, ruined countless athletic performances, and made for lots of poor business decisions. President George Bush may have been feeling the effects of jet lag in 1992, when he vomited and fainted at a state dinner in Japan.

Unfortunately, there's no foolproof means of staving off jet lag, but here are some tips on how to minimize its effects:

•Before departure, gradually shift your sleep-wake cycle -- at the rate of one hour per day -- to match that of your destination. Once you're in the air, reset your watch right away. If it's night at your destination, try to sleep on the plane. Wearing an eye mask and earplugs or headphones can diminish light and noise. To avoid getting jostled by other passengers, ask for a window seat. If it's daytime where you're headed, stay awake. Keep your light on. Read a thriller. Get up frequently and cruise the aisles.

•During your flight, drink plenty of water or juice to offset dehydration from the dry cabin air, which can exacerbate the effects of jet lag. Don't choose alcoholic or caffeinated drinks, which will make you even more dehydrated.

•If you arrive in the daytime, resist the urge to nap. Try to stay up until local bedtime. Spend as much time as possible outdoors in natural light, which helps reset your biological clock.

•You may also want to consider taking a short-acting sleeping pill while on the plane and for the first few nights after arrival, if you're having trouble adjusting to local time and are unable to sleep. However, all sleeping pills, both over-the-counter and prescription types, can have a hangover effect. Instead of feeling alert and well-rested, you may wake up feeling groggy.

A researcher at the Argonne National Laboratory in Illinois came up with an anti-jet lag diet a while back -- a complex protocol of fasting, precisely scheduling meals, and alternating foods high in protein and carbohydrates. In two controlled studies most people found the diet to be slightly helpful, but a few reported that it actually worsened their jet lag. What's more, you have to begin the regimen several days before departure, which isn't practical for many people. Researchers are investigating a simpler method of using diet to prevent jet lag based on the idea that foods high in carbohydrates, such as pasta, may promote sleep, while foods high in protein can help you stay awake. So, if you arrive in London at 8 am and your eyelids are drooping, forgo the crumpets and order an omelet instead.

You can try. Melatonin is a hormone produced by the brain's pineal gland that helps regulate your daily rhythms, including the sleep-wake cycle. Your body's production of melatonin peaks during the night and then tapers off as daylight approaches. But when you fly across several time zones, your rhythms get disrupted. Some researchers believe that by taking a melatonin supplement at the time when your body would normally release the hormone, you may be able to reset your internal clock more quickly, but there's no standard dose or regime for jet lag, and recommendations vary widely.

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Last updated January 26, 2009
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