DALLAS — For many travelers who cross several time zones, the exhilaration of taking in sights like the Eiffel Tower or the pyramids of Egypt is quickly tempered by the grogginess of jet lag.

Veteran fliers often have their own remedies to overcome those signals from the body that it's time for sleep. But an Oregon researcher recently detailed in The New England Journal of Medicine three basic strategies for overcoming jet lag:

• Reset the circadian clock that tells a person to stay awake during the day and sleep at night. You can do this by taking the sleep-inducing hormone melatonin, timing your exposure to bright light, or both.

• Adjust your sleep schedule. Take short naps if you are sleepy the first few days after arrival. If you can, shift your sleep schedule by a couple of hours before travel.

• Use medications to get to sleep or stay awake. Or turn to the old reliable remedy for keeping your eyes open: caffeine.

"We have mechanisms to adjust our clocks, but those mechanisms have to be called on to go into high gear," said Dr. Robert Sack, a psychiatry professor at Oregon Health & Science University in Portland, Ore., whose article takes a science-based look at jet lag remedies.

Sack said melatonin is the most extensively studied jet lag treatment, with a majority of double-blind, placebo-controlled trials showing it helped symptoms.

"Its effect is based in good science," Sack said. He said the U.S. Food and Drug Administration has not evaluated melatonin, but no significant adverse effects have been reported.

Melatonin is sold as a nutritional supplement in the U.S. and no prescription is needed for it.

No drugs have been approved by the FDA for jet lag, but Sack says drugs that help with alertness or insomnia can alleviate jet lag.

So for eastward travel, from the U.S. to Paris for example, on arrival a traveler might go for a walk in the sun and then sip a latte at an outdoor cafe. Sack said travelers who are unbearably sleepy as the day wears on should take a short nap. Then take melatonin — a dose of 0.5 to 3 milligrams — before heading to bed and hopefully you'll be adjusted to your new time zone within a couple of days.

For westward flights — such as Europe back to the U.S. — travelers should expose themselves to bright light in the evening to help them stay up later, then if their eyes pop open before 5 a.m., take a low dose of melatonin.

"Your internal dawn is occurring before you want it to," Sack said, adding, "it's easier to lengthen your day, which is what you do when you travel westward."

Sack's research was published in February.

As a flight attendant for American Airlines, Debbie Bauer has had her share of jet lag. For instance, after spending about 72 hours making the trip to New Delhi, India, and then returning home, she usually gives herself the day after getting home to recover.

"I don't do anything that requires careful thought," said Bauer, 53, who lives in Arlington, Texas. "It takes its toll on you."