Long-distance air travelers can tell you that they often walk off the plane with tired eyes and a tired body. Unable to concentrate for up to 24-hours, these tourists and business can now get help in the form of a dietary supplement - a coenzyme known as NADH.

"e-NAD-alert" uses a form of stabilized N-A-D-H, a co-enzyme found in the body that stimulates cellular energy production. In a small study, by the makers of e-NAD-alert, 35 passengers were asked to take the medication after a flight from San Diego, California to Pheonix, Arizona, which waws followed by another flight to Baltomore and a bus trip to Washington, DC. The company hoped to test how jet lag affected brain function and whether or not their supplement could reduce the brain-numbing effect of jet lag.

One of the subjects, Nancy Cavanaugh, said she was having problems staying awake. "On the trip from Baltimore to Washington, I could feel my eyes were tired. I was almost falling asleep," she said.

Once they arrived in Washington, some of the subjects were given 20 milligrams of e-NAD-alert. Another group was given a placebo. Researchers said the placebo group was drowsier, with reaction times up to six-tenths of a second slower than the e-NAD-alert group.

The principal investigator of the study pointed out the slower reaction time can be dangerous, especially if someone is jet lagged and gets behind the wheel. "If you're traveling 60-70 miles an hour, that distance can become rather meaningful," said Dr. Gary Kay.

Not everyone is convinced of the powers of e-NAD-alert.

"The results are just too preliminary and the study is too small to make any broad conclusions about its use," said Richard Waldhorn of the Georgetown University Sleep Disorders Center.

Waldhorn said travelers passing through fewer than 6 time zones don't need any drugs or supplements to cope with jet lag. He suggested they simply avoid late meals and alcohol, and adjust their exposure to sunlight.