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.
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.
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.
What are the best ways to cope with jet lag?
There are several home remedies that can help with prevention of jet lag and easier recovery from the symptoms. The following are 12 tips to help travelers to avoid or to minimize the effects of jet lag.
Some simple behavioral adjustments before, during and after arrival at your destination can help minimize some of the side effects of jet lag.
Select a flight that allows early evening arrival and stay up until 10 p.m. local time. (If you must sleep during the day, take a short nap in the early afternoon, but no longer than two hours. Set an alarm to be sure not to over sleep.)
Anticipate the time change for trips by getting up and going to bed earlier several days prior to an eastward trip and later for a westward trip.
Upon boarding the plane, change your watch to the destination time zone.
Avoid alcohol or caffeine at least three to four hours before bedtime. Both act as “stimulants” and prevent sleep.
- at a destination, avoid heavy meals (a snack—not chocolate—is okay).
- Avoid any heavy exercise close to bedtime. (Light exercise earlier in the day is fine.)
- Bring earplugs and blindfolds to help dampen noise and block out unwanted light while sleeping.
- Try to get outside in the sunlight whenever possible. Daylight is a powerful stimulant for regulating the biological clock. (Staying indoors worsens jet lag.)
- Contrary to popular belief, the type of foods we eat have no effect on minimizing jet lag.
According to experts, stress or the potential for stress is another problem that can lead to sleeplessness. Two common travel related stress conditions are the “First Night Effect” and the “On-Call Effect.” The first condition occurs when trying to sleep in a new or unfamiliar environment.
The second is caused by the nagging worry that something just might wake you up, such as the possibility of a phone ringing, hallway noise or another disruption.
Try these tips on you next trip to help avoid travel-related stress and subsequent sleeplessness.
Bring elements or objects from home like a picture of the family, favorite pillow, blanket or even a coffee mug) to ease the feeling of being in a new environment.
Check with the hotel to see if voice mail services are available to guests. Then, whenever possible, have your calls handled by the service.
Check your room for potential sleep disturbances that may be avoided; e.g., light shining through the drapes, unwanted in-room noise, etc.
Request two wake-up calls in case you miss the first one.