Here are some tips to help prevent jet lag:
Maintain a sensible bedtime schedule before your trip. Don't avoid sleeping in order to make yourself tired.
Consider going to bed earlier for a couple of nights before leaving if you are traveling east. Go to bed later for a couple of nights if you are traveling west.
For short trips, maintain a schedule of eating and sleeping at your usual times, if possible, while at your destination. For longer trips, try to adapt to the time schedule to which you're traveling before you leave. Set your watch to the new time as you begin the trip.
While in flight, avoid sleeping at times that wouldn't be appropriate for sleep at your destination.
Make the most of any stopovers by making yourself comfortable and getting rest.
Drink plenty of liquids, but avoid alcohol and caffeine.
If you exercise regularly, continue to do so at your destination. Avoid exercising late in the evening, because it can keep you awake.
For important events or meetings at your destination, try to arrive ahead of time to allow for the time difference.
Melatonin, a hormone sold in supplement form at health food stores, may help decrease jet lag. While in flight, consider taking some melatonin (generally 3 - 5 milligrams) at the time at which it would be appropriate to sleep at your destination. Then try taking melatonin several hours before bedtime for several days once you arrive at your destination.