Jet lag
| Jet lag | |
|---|---|
| Classification and external resources | |
| Specialty | neurology |
| ICD-10 | G47.25 |
| ICD-9-CM | 307.45, 780.50 327.35 |
| DiseasesDB | 7045 |
| MeSH | D021081 |
Jet lag, medically referred to as desynchronosis and rarely as circadian dysrhythmia, is a physiological condition which results from alterations to the body's circadian rhythms resulting from rapid long-distance trans-meridian (east–west or west–east) travel on high-speed aircraft. For example, someone travelling from New York to London feels as if the time were five hours earlier than local time. Jet lag was previously classified as one of the circadian rhythm sleep disorders.
The condition of jet lag may last several days before the traveller is fully adjusted to the new time zone; a recovery period of one day per time zone crossed is a suggested guideline. Jet lag is especially an issue for airline pilots, crew, and frequent travellers. Airlines have regulations aimed at combating pilot fatigue caused by jet lag.
The term "jet lag" is used because before the arrival of passenger jet aircraft, it was uncommon to travel far and fast enough to cause jet lag. Travel by propeller-driven aircraft, by ship or by train was slower and of more limited distance than jet flights, and thus did not contribute widely to the problem.
Jet lag is a chronobiological problem, similar to issues often induced by shift work and the circadian rhythm sleep disorders. When travelling across a number of time zones, the body clock (circadian rhythm) will be out of synchronisation with the destination time, as it experiences daylight and darkness contrary to the rhythms to which it has grown accustomed. The body's natural pattern is upset, as the rhythms that dictate times for eating, sleeping, hormone regulation, body temperature variations, and other functions no longer correspond to the environment, nor to each other in some cases. To the degree that the body cannot immediately realign these rhythms, it is jet lagged.
The speed at which the body adjusts to the new schedule depends on the individual as well as the direction of travel; some people may require several days to adjust to a new time zone, while others experience little disruption.
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