Alternative Names: Jet-lag, Jetlag, Desynchronosis, Dysrhythmia, Dyschrony, or Jet Syndrome.
Jet Lag comes as a consequence of alterations to the circadian rhythm that result from shift work, daylight saving time, altered day length, or long-distance journeys by aircraft across several time zones. The condition is generally believed to be the result of disruption of the "light/dark" cycle that governs the body's circadian rhythm, and can be exacerbated by environmental factors. If you are frequently changing time zones or working long and/or varying hours or shifts, you start working at only 60 to 70% of your potential until jet lag has been overcome. You lose concentration, judgement, and reaction time.
Jet lag is not linked to the length of flight in hours, but to the transmeridian (i.e. longitudinal or east-west) distance traveled. For example, a ten-hour flight between Frankfurt and Johannesburg (going south, staying roughly on the same meridian) is unlikely to cause jet lag compared with a five-hour flight between New York and Los Angeles (going west three time zones).
There seems to be some evidence that traveling west to east is more disruptive, or runs counter to the circadian rhythm. Different individuals may find one adjustment easier than the other.
Note that there is a big difference between a -6 and a +6 hours jet lag, there is relatively small difference between -11 and +11 hours. Crossing the International Date Line does not affect jet lag in itself.
Jet lag occurs because the body cannot automatically realign these rhythms. The speed at which the body readjusts itself to new daylight and darkness hours, and eating and sleeping patterns, is entirely dependent upon the individual. Thus, while it may take little or no time for some people to readjust to a new time zone, others seem to experience significant disruption to their body's natural sleeping pattern.
For occasional flights, it can be an effective non-drug remedy to skip sleep entirely for one night and one day and then go to bed at a normal destination-area bedtime. It may even work better not to sleep the night before the flight. These tactics allow a relatively quick recovery for many people.
Most chemical and herbal remedies are not tested or approved by the Food and Drug Administration.
Prevention of Jet Lag can be simple: good sleep while aboard a plane and an adequate intake of fluids (without excessive amounts of caffeine or alcohol) to reduce the effects of dehydration and the interruption of regular eating/drinking patterns. Seasoned travelers set their clock to the destination time zone, as soon as it is practical, and join the new rhythm.