Traveling, whether by car, train, or airplane, may result in fatigue, which often lasts less than 24 hours. However, when one travels long distances by airplane (across 3 or more time zones), one may experience a number of symptoms that persist beyond what would normally be expected due to prolonged travel alone. This condition is referred to as "jet lag." Jet lag may result in various symptoms including uneasiness, daytime fatigue, muscle aches, headache, moodiness, and especially difficulty in falling asleep or maintaining sleep. Jet lag results from a conflict between a traveler's internal clock that is normally in synchrony with the usual sleep-wake and meal schedule in the region prior to travel with the sleep-wake schedule of the new time zone. Therefore, a traveler may feel the urge to eat dinner when it is 3 AM in the new time zone or feels like sleeping when it is 2 PM. Jet lag appears to be more severe the more time zones traveled, and traveling eastward appears to make it more difficult to adjust to the new time zone than when traveling westward. Adjusting one's sleep and meal schedule to the new time zone may take time, often 1 day for each time zone traveled. In addition, individuals over 50 years of age may have a more difficult time adjusting to the new time zone than younger individuals.
One may attempt countermeasures to minimize jet lag. These include:
1. Prior to travel, adjust your sleep-wake pattern and mealtime schedule to match the destination time.
2. Avoid napping or sleeping at inappropriate times in the new location. Follow the sleep-wake schedule in the new location.
3. Get plenty of exposure to sunlight in the new location. This will help to readjust your internal clock to match daytime and nighttime in the traveled location.