The Physiology of Jet Lag


The term “jet lag” is a fairly common one among air travelers, and it refers to the feeling of being out of sync with a new time zone after traveling a long distance. Given the number of people who regularly travel across several time zones, from global businesspeople and elite athletes to the flight crews of planes themselves, scientists have conducted a considerable amount of research into the phenomenon and its causes.

Jet lag happens because the body has an internal system that reacts to the daytime/nighttime cycle of the Earth. Called the circadian rhythm, this “internal clock” regulates important systems like fatigue, appetite, and body temperature. Your circadian rhythm adapts to local conditions, but it cannot keep up with jet aircraft capable of flying at high speed for several hours and landing in a new place where the local time remains unchanged.

Researchers have identified two areas in the brain affected by jet lag. Both are located near the base of the brain, and one is linked to deep sleep that results from physical exhaustion. The other is associated with a type of sleep called REM sleep, during which the eyes move rapidly and dreams occur. When jet lag disturbs these areas of the brain, a number of symptoms occur. Travelers may be drowsy and irritable or disoriented. Traveling greater distances typically results in more severe symptoms, and older passengers tend to be at greater risk of jet lag than younger ones. Extra stress from factors like heat or humidity can make the symptoms worse.

Treatment of jet lag can take many forms. It may be prevented or ameliorated by physical fitness and a balanced diet. Maintaining good control of any underlying medical conditions such as diabetes and heart disease can also minimize its effects. The best treatment is often to adjust to the new schedule at your destination as quickly as possible, even if that means staying up when you’re tired or trying to sleep when you feel alert.