It's the curse of the well-traveled. Is there any way to avoid jet lag? People have tried everything: fasting, drinking water, naps, herbal remedies, Valium, Ambien, Dramamine, watches that automatically change time zones, special diets, exercise, strange preflight bedtimes and even 1984 Cockburn's port.

None of those things hurt, but there are only three things that have been proven to help, according to experts: time, light and maybe the hormone melatonin.

That's because your body takes about one day to adjust its circadian rhythm, an internal biological clock, for every time zone you cross, says sleep researcher Christopher Drake.

"The more time zones you cross, the more difficult it is," says Drake, a senior staff psychologist at the Henry Ford Hospital Sleep Disorders and Research Center in Detroit. "You are trying to match your body clock with your body processes."

Normally, stable hormones and other physical cues tell your body when it's day and night. But when you travel three hours or more east or west, your body gets confused.

The primary symptoms of jet lag are daytime grogginess and nighttime wakefulness. Many people also have stomach upset, although scientists aren't sure why.

Most travelers adjust more easily when traveling west.

"Our bodies more easily delay sleep," says Drake. "We can go to bed later more easily than go to bed early. But there are individual differences."

Some people aren't bothered much by jet lag at all.

"Usually when we go to Europe, we take a one- or two-hour nap as soon as we get to the hotel, and after that, we have no problem," says Nancy Keith of Yale, who has been to Europe about nine times and never sleeps on the plane.

People who don't get enough sleep and who have a chronic sleep debt may do better at falling asleep on trips and avoiding jet lag, Drake says.

But sleep is more and more elusive on full flights and tighter spaces on air carriers.

There is also some indication that young people adjust faster than older travelers to time changes.

If you are traveling only a few days, it might be better to stay on your home time if you can.

What about sleeping pills? Yes, Drake says, they can work in the short term on the airplane or to help you fall asleep when your body still thinks it is daytime. But don't use over-the-counter sleeping pills — they last up to 10 hours and can cause a groggy hangover.

Talk to your doctor for something more short-acting. Use only as directed.

What about melatonin? The hormone associated with sleep is not a sleeping pill. It's a chronobiotic that helps readjust your body's night-day time clock.

"Melatonin minimizes the effect that light has on our circadian rhythm, but it can also be a soporific," Drake says.

You can buy it at drug stores in 0.3- to 3-milligram strengths.

Some swear by homeopathic remedies such as No-Jet-Lag pills sold by travel-gear companies. Do they work?

"There have been no controlled studies on herbal medications in terms of efficacy," Drake says.

But if it works for you, hey, go for it. Anything to help you zzzzz ...

WAYS TO ADJUST YOUR BODY CLOCK

Here are just a few ways travelers can minimize the effect of jet lag: