Jet lag, also jetlag or jet-lag, is a physiological conition which is a consequence of alterations to circadian rhythms; it is classified as one of the circadian rhythm sleep disorders. Such disturbances result from shift work, daylight saving time, chronic congenital disorders, or as the name implies, rapid transmeridian travel as on a jet plane. They are known as desynchronosis, dysrhythmia, dyschrony, jet lag, or jet syndrome. The condition is generally believed to be the result of disruption of the "light/dark" cycle that entrains the body's circadian rhythms.