Jet lag is an imbalance of ones body’s natural “biological clock” due to traveling between different time-zones. The symptoms of jet lag consist primarily of insomnia and daytime sleepiness but can also include mood changes, reduced physical performance, cognitive impairment and gastrointestinal disturbances 1 . The severity of jet lag symptoms is affected by both the number of time zones crossed and the direction of travel, where flying westward is easier to tolerate than flying eastward. Jet lag symptoms last until the circadian system is realigned with the new time zone.
The clinical problem of Jet lag-
Jet lag is known as a sleep disorder that results from crossing time zones too rapidly for the biological clock to keep pace. The pathophysiology involves a temporary misalignment between the biological clock and local time. The biological clock, located in the brain, is normally synchronized to the solar light–dark cycle and promotes alertness during the day and sleep at night. When traveling to a new time zone, the biological clock is slow to reset, so that after time zones have been crossed, the body internal signals for sleep and wakefulness do not match the local light–dark and social schedules 2 .
Management of Jet lag-
Sunlight has a major influence on the internal biological clock and the general consensus is that the timing of exposure to light is the most important time cue for synchronizing circadian rhythms in humans. Exposure to light in the evening shifts the clock to a later time, and exposure to light in the morning shifts the clock to an earlier time. For those who travel frequently and are unable to have exposure to natural sunlight, light therapy (a light box, a lamp, and a light visor) may be a viable option. Light synchronizes the body clock by exposing the eyes to an artificial bright light that simulates sunlight for brief periods at planned times during the day 3 .
Many chronic travelers such as air force aircrew and shift workers use different medication to cope with the jet lag among them Benzodiazepenes and z-drugs. These drugs might be effective in the treatment of insomnia 4 but they also have negative effects such as dependence, daytime residual disturbances, cognitive and psychomotor impairments, falls and accidents, memory disturbances and dementia 5 .
Melatonin (darkness signal) is a hormone that is secreted for about 8 to 10 hours at night and facilitates sleep. Melatonin was long believed to be the major endocrine output signal of the endogenous time measuring and time keeping system that synchronizes the remainder of the body with clock 6 .
Consequently, externally applied melatonin is used to treat desynchronization of circadian rhythms caused by jet lag or shiftwork 7 . Most of the benefits of melatonin with respect to jet lag are related to its biological clock-resetting effects, but melatonin also has some direct hypnotic, sleep-inducing, activity 8 . Melatonin, in contrast to the traditional hypnotic, has a safe profile with no dependency, withdrawal effect or abuse and has no impact on psychomotor performance 9 .