What causes jet lag?
Jet lag mainly occurs in people who rapidly traverse multiple time zones. Traveling between time zones changes the light-dark patterns in your environment, it can disrupt your body's rhythms. A change of even a few hours may not seem
significant, but often it is enough to affect the body's sleep-wake cycle. Children less than three years of age do not seem to experience jet lag because they are more adaptable and less set in their ways. Adults who can easily adjust to changes in routine are less susceptible to jet lag, and those who stick to a fixed daily routine often suffer more.
Hypothalamus in brain acts as a kind of alarm clock to activate various body functions such as hunger, thirst, and sleep. It also regulates body temperature, blood pressure, and the level of hormones and glucose in the bloodstream. To help the body tell the time of day, fibers in the optic nerve of the eye transmit perceptions of light and darkness to a time-keeping center within the hypothalamus. Thus, when the eye of an air traveler perceives dawn or dusk many hours earlier or later than usual, the hypothalamus may trigger activities that the rest of the body is not ready for, and jet lag occurs.