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February 3, 2012
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Jet Lag

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What is jet lag?

Jet lag, also called desynchronosis and flight fatigue, is a temporary disorder that causes fatigue, insomnia, and other symptoms as a result of air travel across time zones. It is considered a circadian rhythm sleep disorder, which is a disruption of the internal body clock.

What are other symptoms and signs of jet lag?

Besides fatigue and insomnia, a jet lag sufferer may experience a number of physical and emotional symptoms including anxiety, constipation, diarrhea, confusion, dehydration, headache, irritability, nausea, sweating, coordination problems, dizziness, and even memory loss. Some individuals report additional symptoms, such as heartbeat irregularities and increased susceptibility to illness.

Children can also suffer the same jet lag symptoms as adults.

What is a time zone?

A time zone is a geographical region which has the same time everywhere within it. The world has 24 time zones, one for each hour in the day. Each zone runs from north to south in strips that are approximately 1,000 miles (1,600 kilometers) wide. (The actual width of each zone varies to accommodate political and geographical boundaries.) As the earth rotates, dawn occurs at a set hour in one time zone, then an hour later in the time zone immediately to the west and so on through the 24-hour cycle. Thus, in the U.S., when it is 6 a.m. in the eastern time zone, it is 5 a.m. in the central zone, 4 a.m. in the mountain zone, and 3 a.m. in the Pacific zone.

Why does jet lag occur?

The cause of jet lag is the inability of the body of a traveler to immediately adjust to the time in a different zone. Thus, when a New Yorker arrives in Paris at midnight Paris time, his or her body continues to operate on New York time. As the body struggles to cope with the new schedule, temporary insomnia, fatigue, irritability, and an impaired ability to concentrate may set in. The changed bathroom schedule may cause constipation or diarrhea, and the brain may become confused and disoriented as it attempts to juggle schedules.

How does the body keep time?

Our bodies have a sort of internal biological clock that follows a 24-hour cycle, called a circadian rhythm. A tiny part of the brain called the hypothalamus acts like an alarm clock to activate various body functions such as hunger, thirst, and sleep. It also regulates body temperature, blood pressure, and the level of hormones and glucose in the bloodstream. To help the body tell the time of day, fibers in the optic nerve of the eye transmit perceptions of light and darkness to a timekeeping center within the hypothalamus. Thus, when the eye of an air traveler perceives dawn or dusk many hours earlier or later than usual, the hypothalamus may trigger activities that the rest of the body is not ready for, and jet lag occurs.


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Jet Lag

What is the Eustachian tube?

The Eustachian tube is a tube that originates in the back of the nose, runs a slightly uphill course, and ends in the middle ear space. The middle ear space is the hollowed out portion of the skull bone that contains the hearing apparatus and is covered on one side by the eardrum. In adults, the Eustachian tube is approximately 35 mm long (1.3 inches) and approximately 3 mm in diameter (less than 1/10 inch). Cartilage provides the supporting structure for the first two-thirds of the Eustachian tube, with the last third (the part closest to the middle ear space) being made of bone.

The tissue that lines the Eustachian tube is similar to that inside the nasal cavity and may respond the same way (swelling) when presented with similar stimuli. The Eustachian tube was named in honor of the 16th century Italian anatomiast Eustachius. Sources credit Almaceon of Sparta as the first to describe the structure in approximately 400 BC...

Read the Eustachian Tube Problems (Problems Clearing Your Ears) article »







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