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- Patient Comments: Jet Lag - Remedies
- Patient Comments: Jet Lag - Symptoms
- Patient Comments: Jet Lag - Coping
- Patient Comments: Jet Lag - Direction of Travel
- What is jet lag?
- What are other symptoms and signs of jet lag?
- How long does jet lag last?
- What is a time zone?
- What causes jet lag?
- How does the body keep time?
- Does the direction of travel matter?
- Do the symptoms of jet lag vary in intensity?
- What are risk factors for jet lag?
- Are there any remedies for jet lag? Is it possible to prevent jet lag?
- What is the treatment for jet lag?
- Are there effective medications for jet lag? What is the role of melatonin in jet lag?
What is a time zone?
The definition of 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.
What causes jet lag?
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. So, 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.