Jet Lag: an alteration of circadian rhythms following trans-meridian flight that causes the traveler to be out of sync with the external environment. It makes those who travel across time zones feel inappropriately tired throughout the day, yet awake at night. Jet Lag can be strong enough to interfere with travel plans.


  Jet Lag results from travel to a place where circadian clocks are naturally set to a different time. The sun rises and sets significantly earlier or later. People eat, socialize and sleep at a different time than the traveler’s normal schedule.
    Travelers may complain of disturbed sleep or difficulty awakening. Sleep loss makes for tiredness the following day.  Jet lag sufferers may also experience a feeling of malaise. Other problems include nausea, diarrhea, headache, air sickness, and irritability. As the name implies, rapid travel across time zones precipitates these symptoms, not the length of a flight. A ten hour, non-stop flight from northern Canada to the southern tip of South America might produce malaise related to confinement on with other people as opposed to circadian disruption.
   How jet lag affects sleep and wakefulness also depends on which direction time zones are crossed. East to west travel is generally less troublesome because it is easier to stay up a few hours later than it is to 'force' oneself to sleep earlier. Travel east or west across the International Date Line (IDT), where the eastern-most time zone meets the western-most time zone does not produce symptoms of Jet Lag because the actual time difference does not affect circadian rhythms.


   People with jet lag usually overcome it on their own. Frequent travelers with persistant jet lag may benefit from a sleep evaluation. A diary  of your sleep habits during travel will help. The log should reflect actual sleep times as well as your "normal" time zone, as well as the time zones of your destinations. Testing in a sleep laboratory will only be necessary if another sleep disorder is suspected.


     Begin adjusting ahead to time to the new zone. Avoid caffeine after noon and alcohol within four hours of bedtime. If necessary, use a full spectrum lamp or portable visor set to 10000 lux for 30 to 90 minutes immediately upon awakening, or just before getting up. Exposure to sunlight at this time may also help.

For east to west travel: Go to bed later on the day of arrival to accomodate the earlier time zone.
For west to east travel: Stay up until you feel tired following arrival, yet force yourself awake at the new wake time. Avoiding naps may then produce an earlier sleep onset on the second night.

Jet Lag Mechanics 

      Jet Lag is a circadian rhythm disorder or one that disrupts the cycle of sleep and wakefulness, among other bodily functions. Daylight cues the activation of neurochemicals that produce alertness and physical activity. The presence of lightness also decreases the production of melatonin, which makes us sleepy. Darkness promotes sleep by increasing the production of melatonin. Once asleep, our bodies engage in hormone regulation and other nocturnal activites.
     Jet lag misaligns environmental cues with our internal clock. Adjusting our internal clock to a new time zone takes more time than the average trip allows. As a result, sleep, hormone regulation and other bodily functions suffer.

Suggested Downlaods

Out of Sync