Jet Lag Susceptibility

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, judgment, 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.

Causes and Development

When traveling across a number of time zones, one's body clock loses its synchronization with the local time.  The same happens when changing from a day shift to a night shift at work, for example.  The result is that we experience daytime and nighttime contrary to the rhythms to which we have been accustomed.  This natural pattern is upset as our needs for eating and sleeping no longer correspond our environment.

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.

Signs and Symptoms

The symptoms of jet lag are varied but commonly include:

• Dehydration and loss of appetite
• Headaches and/or sinus irritation
• Fatigue
• Disorientation and/or grogginess
• Nausea and/or upset stomach
• Insomnia and/or highly irregular sleep patterns
• Irritability and/or irrationality.

Jet lag, when present, generally lasts a few days.

Treatment and Prevention

The experience of jet lag varies among different individuals, so it is difficult to assess the efficacy of any single remedy.  Exposure to sunlight may be a factor to reset the body's clock.  Sleep, relaxation, moderate exercise, and sensible diet seem to be the simplest recovery methods.

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.