[Jet lag]

It is known that time-zone fatigue (jet lag syndrome) a transient physiological and mental condition occurs when people travel by jet between zones with time differences of five hours or longer. Jet lag syndrome is considered to develop because of internal desynchronization that results from a sudden difference between biological rhythm and living time. Among the symptoms of time-zone fatigue sleep-wakefulness disorder is observed most frequently. Utilizing external synchronous factors and careful use of medication are effective in preventing the syndrome.