Disease: Jet Lag

    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, difficulty concentrating, sweating, coordination problems, dizziness, and even memory loss. Some individuals report additional symptoms, such as heartbeat irregularities and increased susceptibility to illness.

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

    Generally, people to not need a medical evaluation for a diagnosis of jet lag. If you have traveled across several time zones and feel the symptoms associated with jet lag, you likely have it. If your symptoms of jet lag are severe, do not go away after a few days, or you have any other concerns, see a doctor.

    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.

    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.

    What is the role of melatonin in jet lag?

    Melatonin is a hormone that plays a key role in body rhythms and jet lag. After the sun sets, the eyes perceive darkness and alert the hypothalamus to begin releasing melatonin, which promotes sleep. Conversely, when the eyes perceive sunlight, they tell the hypothalamus to withhold melatonin production. However, the hypothalamus cannot readjust its schedule instantly; it takes several days.

    Does the direction of travel matter?

    Yes. Travelers flying north or south in the same time zone typically experience the fewest problems because the time of day always remains the same as in the place where the flight originated. These travelers may experience discomfort, but this usually results from confinement in an airplane for a long time or from differences in climate, culture, and diet at the destination location. Time differences do not play a role.

    Travelers flying east, on the other hand, typically experience the most problems because they "lose" time. For example, on an international flight from Washington, D.C., to Mecca, Saudi Arabia, a traveler loses eight hours. Meals, sleep, bowel habits, and other daily routines are all pushed ahead eight hours.

    Travelers flying west "gain" time and usually have an easier time adjusting than eastward travelers. However, they too experience symptoms of jet lag after landing because they still must adjust to a different schedule.

    Do the symptoms of jet lag vary in intensity?

    Yes. People flying across only one or two time zones may be able to adjust without noticeable effects of the time change. Those flying across three or more time zones will likely develop noticeable symptoms of jet lag. Generally, the intensity of symptoms varies in relation to the number of time zones crossed and the direction of travel. People also vary in their susceptibility to jet lag symptoms and the severity of the symptoms.

    What are risk factors for jet lag?

    The main cause of jet lag is travel across different time zones. However, there are certain risk factors that may result in symptoms being more severe or longer-lasting.

    • Travel across three or more time zones: Most people can adjust rapidly to a one or two time zone change. Three or more may cause more noticeable symptoms of jet lag.
    • Flying east: As stated previously, travel from west to east causes travelers to "lose" time, and this can be a more difficult adjustment.
    • Age: Older adults may recover from jet lag more slowly.
    • Frequent travel: Pilots, flight attendants, and frequent business travelers who are constantly in different time zones may have difficulty adjusting.
    • Preexisting conditions: Preexisting sleep deprivation, stress, and poor sleep habits prior to travel can exacerbate jet lag symptoms.
    • Flight conditions: The monotony of travel, immobility and cramped seating, airline food, altitude, and cabin pressure can impact jet lag symptoms.
    • Alcohol use: Overconsumption of alcohol during long flights can also worsen the symptoms of jet lag.

    How long does jet lag last?

    Recovering from jet lag depends on the number of time zones crossed while traveling. In general, the body will adjust to the new time zone at the rate of one or two time zones per day. For example, if you crossed six time zones, the body will typically adjust to this time change in three to five days.

    Jet lag is temporary, so the prognosis is excellent and most people will recover within a few days.

    Complications of jet lag are extremely rare. If a person has a preexisting heart condition, the stress of the disruption in the circadian rhythm, combined with the stress of travel, the high altitude, and immobility during flight may result in a heart attack. If the jet lag results in chronic sleep deprivation, stroke may occur in certain predisposed individuals.

    Should people take melatonin for jet lag?

    Another option is synthetic melatonin, which is classified in the U.S. as a dietary supplement. A study in the British Medical Journal in 1989 reported that taking synthetic melatonin tablets can help travelers restore normal sleeping patterns. In that study, 20 volunteers traveling back and forth between New Zealand and England took daily doses of either 5 mg of melatonin or a placebo (a blank, or sugar pill) before, during, and after their flights. Those taking melatonin returned to their normal sleep patterns in 2.85 days on average compared with 4.15 days for those taking a placebo.

    However, scientists in the U.S. and many other countries are not yet convinced that enough evidence exists to prove the efficacy of over-the-counter (OTC) melatonin tablets. These scientists also point out the following:

    1. No information has been compiled on the long-term effects of taking melatonin.
    2. No watchdog measures are in place to assure that all OTC melatonin products meet minimum standards.

    In 2005, MIT released the results of a meta-analysis of 17 peer-reviewed studies using melatonin. It showed that melatonin was effective in helping people fall asleep at doses of 0.3 mg. Larger doses of melatonin seem to be less effective after only a few days' use.

    For the purpose of treating jet lag, it is suggested that a dose between 0.3 mg-5 mg of melatonin be taken on the first day you travel at the time you will want to go to sleep at your destination. This may be continued at bedtime for a few days once you are at your destination. Melatonin seems to be most effective when crossing five or more time zones, or traveling east. Only adults should take melatonin. Do not drink alcohol when taking melatonin.

    Be aware that higher doses of melatonin can cause sleepiness, lethargy, confusion, and decreased mental sharpness. Operating motor vehicles or heavy machinery should be avoided after taking your daily dose of melatonin. Consult a doctor if planning on taking melatonin.

    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.

    What is the role of melatonin in jet lag?

    Melatonin is a hormone that plays a key role in body rhythms and jet lag. After the sun sets, the eyes perceive darkness and alert the hypothalamus to begin releasing melatonin, which promotes sleep. Conversely, when the eyes perceive sunlight, they tell the hypothalamus to withhold melatonin production. However, the hypothalamus cannot readjust its schedule instantly; it takes several days.

    Does the direction of travel matter?

    Yes. Travelers flying north or south in the same time zone typically experience the fewest problems because the time of day always remains the same as in the place where the flight originated. These travelers may experience discomfort, but this usually results from confinement in an airplane for a long time or from differences in climate, culture, and diet at the destination location. Time differences do not play a role.

    Travelers flying east, on the other hand, typically experience the most problems because they "lose" time. For example, on an international flight from Washington, D.C., to Mecca, Saudi Arabia, a traveler loses eight hours. Meals, sleep, bowel habits, and other daily routines are all pushed ahead eight hours.

    Travelers flying west "gain" time and usually have an easier time adjusting than eastward travelers. However, they too experience symptoms of jet lag after landing because they still must adjust to a different schedule.

    Do the symptoms of jet lag vary in intensity?

    Yes. People flying across only one or two time zones may be able to adjust without noticeable effects of the time change. Those flying across three or more time zones will likely develop noticeable symptoms of jet lag. Generally, the intensity of symptoms varies in relation to the number of time zones crossed and the direction of travel. People also vary in their susceptibility to jet lag symptoms and the severity of the symptoms.

    What are risk factors for jet lag?

    The main cause of jet lag is travel across different time zones. However, there are certain risk factors that may result in symptoms being more severe or longer-lasting.

    • Travel across three or more time zones: Most people can adjust rapidly to a one or two time zone change. Three or more may cause more noticeable symptoms of jet lag.
    • Flying east: As stated previously, travel from west to east causes travelers to "lose" time, and this can be a more difficult adjustment.
    • Age: Older adults may recover from jet lag more slowly.
    • Frequent travel: Pilots, flight attendants, and frequent business travelers who are constantly in different time zones may have difficulty adjusting.
    • Preexisting conditions: Preexisting sleep deprivation, stress, and poor sleep habits prior to travel can exacerbate jet lag symptoms.
    • Flight conditions: The monotony of travel, immobility and cramped seating, airline food, altitude, and cabin pressure can impact jet lag symptoms.
    • Alcohol use: Overconsumption of alcohol during long flights can also worsen the symptoms of jet lag.

    How long does jet lag last?

    Recovering from jet lag depends on the number of time zones crossed while traveling. In general, the body will adjust to the new time zone at the rate of one or two time zones per day. For example, if you crossed six time zones, the body will typically adjust to this time change in three to five days.

    Jet lag is temporary, so the prognosis is excellent and most people will recover within a few days.

    Complications of jet lag are extremely rare. If a person has a preexisting heart condition, the stress of the disruption in the circadian rhythm, combined with the stress of travel, the high altitude, and immobility during flight may result in a heart attack. If the jet lag results in chronic sleep deprivation, stroke may occur in certain predisposed individuals.

    Should people take melatonin for jet lag?

    Another option is synthetic melatonin, which is classified in the U.S. as a dietary supplement. A study in the British Medical Journal in 1989 reported that taking synthetic melatonin tablets can help travelers restore normal sleeping patterns. In that study, 20 volunteers traveling back and forth between New Zealand and England took daily doses of either 5 mg of melatonin or a placebo (a blank, or sugar pill) before, during, and after their flights. Those taking melatonin returned to their normal sleep patterns in 2.85 days on average compared with 4.15 days for those taking a placebo.

    However, scientists in the U.S. and many other countries are not yet convinced that enough evidence exists to prove the efficacy of over-the-counter (OTC) melatonin tablets. These scientists also point out the following:

    1. No information has been compiled on the long-term effects of taking melatonin.
    2. No watchdog measures are in place to assure that all OTC melatonin products meet minimum standards.

    In 2005, MIT released the results of a meta-analysis of 17 peer-reviewed studies using melatonin. It showed that melatonin was effective in helping people fall asleep at doses of 0.3 mg. Larger doses of melatonin seem to be less effective after only a few days' use.

    For the purpose of treating jet lag, it is suggested that a dose between 0.3 mg-5 mg of melatonin be taken on the first day you travel at the time you will want to go to sleep at your destination. This may be continued at bedtime for a few days once you are at your destination. Melatonin seems to be most effective when crossing five or more time zones, or traveling east. Only adults should take melatonin. Do not drink alcohol when taking melatonin.

    Be aware that higher doses of melatonin can cause sleepiness, lethargy, confusion, and decreased mental sharpness. Operating motor vehicles or heavy machinery should be avoided after taking your daily dose of melatonin. Consult a doctor if planning on taking melatonin.

    Source: http://www.rxlist.com

    Another option is synthetic melatonin, which is classified in the U.S. as a dietary supplement. A study in the British Medical Journal in 1989 reported that taking synthetic melatonin tablets can help travelers restore normal sleeping patterns. In that study, 20 volunteers traveling back and forth between New Zealand and England took daily doses of either 5 mg of melatonin or a placebo (a blank, or sugar pill) before, during, and after their flights. Those taking melatonin returned to their normal sleep patterns in 2.85 days on average compared with 4.15 days for those taking a placebo.

    However, scientists in the U.S. and many other countries are not yet convinced that enough evidence exists to prove the efficacy of over-the-counter (OTC) melatonin tablets. These scientists also point out the following:

    1. No information has been compiled on the long-term effects of taking melatonin.
    2. No watchdog measures are in place to assure that all OTC melatonin products meet minimum standards.

    In 2005, MIT released the results of a meta-analysis of 17 peer-reviewed studies using melatonin. It showed that melatonin was effective in helping people fall asleep at doses of 0.3 mg. Larger doses of melatonin seem to be less effective after only a few days' use.

    For the purpose of treating jet lag, it is suggested that a dose between 0.3 mg-5 mg of melatonin be taken on the first day you travel at the time you will want to go to sleep at your destination. This may be continued at bedtime for a few days once you are at your destination. Melatonin seems to be most effective when crossing five or more time zones, or traveling east. Only adults should take melatonin. Do not drink alcohol when taking melatonin.

    Be aware that higher doses of melatonin can cause sleepiness, lethargy, confusion, and decreased mental sharpness. Operating motor vehicles or heavy machinery should be avoided after taking your daily dose of melatonin. Consult a doctor if planning on taking melatonin.

    Source: http://www.rxlist.com

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