Long-distance travellers often experience travel-related fatigue, called jet lag, after flying through several time zones. Jet lag is the result of disrupted body rhythms, and can leave a traveller unable to concentrate, sleep normally or adapt to change for one to three days.
Desynchronosis, also known as jet lag, is a sleep disorder resulting from the rapid alteration of circadian rhythms. The human body has an internal clock that determines when to sleep, wake and eat during a 24-hour period. Long distance travel causes an alteration in the 24-hour period, causing the body to be out of sync with the destination time zone.
Jet lag can last many days, with most people recovering at a rate of one day for each eastward time zone travelled. Westward travel generally requires a recovery rate of one-and-a-half days per time zone. Jet lag is caused by the crossing of time zones, not the length of travel. North to south travel does not cause jet lag.
Symptoms include fatigue, disrupted sleep, insomnia, digestive disorders, headache, irritability, disorientation and inability to concentrate. Jet lag can also cause mild depression.
The recommended method of adjusting is to gradually adjust your sleep schedule over several days, with the goal of sleeping seven to eight hours at a stretch. The objective is to synchronise to the new local schedule. Naps and irregular eating patterns should be avoided.
Jet lag can be minimised by avoiding alcohol and caffeine. Plenty of water and layovers, when convenient, can assist. Sunshine can help moderate symptoms by causing the hypothalamus to slow the production of melatonin during the day, which assists in resetting the internal clock. The hypothalamus is the portion of the brain that sets metabolic functions.
Some studies have indicated that jet lag can be treated with melatonin. A dose of 3 to 5 mg can be taken on the first travel day at the destination's anticipated sleep time. Upon arrival, the melatonin dosage should be continued at bedtime for up to three days.