1. a disturbance of the normal sleep-wake cycle, with the outcome being that the person is alert during a typical sleep time and tired whenever they ought to be alert. 2. an alteration in the circadian or diurnal rhythm facilitated by things like modifications in exposure to daylight or switching between time zones.

PHASE SHIFT: "The phase shifts observed in all the sleep study participants were normal in nature."
Cite this page: N., Pam M.S., "PHASE SHIFT," in, April 7, 2013, (accessed June 4, 2020).