The absence of light and timing of digestion triggers its release into the bloodstream. Melatonin pills are available over the counter but are not sanctioned by the Food and Drug Administration. Your sleeping environment also influences fatigue levels. Some travelers use a blindfold to eliminate light and allow healthful rest. Here are additional tips to ease the problem.
Eastbound travel tends to throw off the body's clock most.
Alter your bedtime several nights before departing on a long trip. If you are flying east, go to bed one hour earlier for each time zone difference. Westbound travelers should retire one hour later for each time zone. Get a decent night's rest before departure and avoid sleeping pills. Sleep at night and stay awake during the day.