Rapid travel over long distances is a fact of life in our society. Jet lag, characterized by fatigue, malaise, sluggishness and disorientation, can affect business or vacation travel plans. This condition is caused by a combination of factors: loss of sleep from flying while keyed up and excited, irregular and unfamiliar meals, dehydration, and disturbance of the biological clock. Prolonged sitting can cause muscle stiffness and constipation in some people.

You can try to take some of the effects out of jet lag in several ways:- Make eastbound flights in daylight hours, leaving as early as possible.

- Make westbound flights late in the day, timing arrival as close to the usual retiring hour as possible.

- Eat light meals; avoid fatty foods. Fast-food restaurants, which seem to be popular sites for meals while traveling, often specialize in high-fat foods that can aggravate already queasy stomachs. Initially, meals should be consumed at times close to the normal time zone; adjustment to the new time zone should occur over several days.

- Get enough sleep before the trip by getting an extra 15 minutes of sleep on each of the last few nights before traveling.

- Dehydration can be a problem during prolonged air travel. Airplanes are pressurized to about 8,000 feet, and the relative humidity is usually less than 20 percent. Under these conditions, the body loses fluid at an increased rate through evaporation. To combat dehydration, drink more water than normal. Plus, more water helps prevent constipation due to long sitting.

- Avoid alcohol since it is a diuretic and can be a factor in causing dehydration.

- Don't nap. Napping delays your adjustment to the new time zone.

- Get out of your seat and stretch or walk around.

- Once you arrive, get out in the sun as much as possible. Some experts feel that the time of day you get out in the sunshine is also important. Light earlier in the day appears to shift the body's clock to an earlier hour, while light later in the day seems to shift the body's clock to a later hour. So if you've traveled west, get outside in the afternoon. If you've traveled east, get outside light in the morning.

- A University of Toronto study indicates that exercise will reduce the number of days jet lag affects you. If you usually go jogging, you should go jogging at your destination. If you don't jog, try walking or some other appealing physical activity.

Don't forget to use these tips for the return trip home since jet lag works both ways.