Jet lag is a disruption of the body's internal biological clock that occurs when people cross time zones.
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Jet lag is a common affliction that has surfaced in recent years. The body's internal clock is "set" for the time zone in which a person lives. The light and dark schedule regulates many body functions, including when the body feels hungry and sleepy. In the past, when people traveled by train, ship, horse, or wagon, long-distance trips took months—more than enough time for the body to continually adjust its clock. Air travel changed all that. Now it is possible to cross 8 or 10 time zones in several hours. This means that the body becomes confused: a person may want to sleep even though it is early morning, or be ready to start the day in the middle of the night.
A contributing factor to jet lag is the stress that air travel places on the body. Flights may have cramped, uncomfortable seating. Even though the cabin is pressurized, it is still like being at 8,000 to 10,000 feet in elevation. The lower air pressure causes minor effects such as headache, body aches, and insomnia. The air aboard airplanes is usually dry, which causes minor dehydration. These stresses and the change in time zones result in jet lag.
Although there is no cure for jet lag, there are things that can help minimize it. During long flights, drink plenty of water, get up and walk around the plane occasionally, and before the trip, begin to adjust eating and sleeping schedules to the hours of the destination.