The deleterious effects of night shift work are discussed in relation to emergency physicians. Much of the early research is drawn from heavy industry sources and must be extrapolated to medical work. Disruption of circadian rhythms and Zeitgebers, caused by adherence to contemporary social schedules, causes recurrent difficulty for physicians who constantly change schedules. Adjustments in both physical surroundings and social structure that can make the effects of traumatic schedule change more tolerable are discussed.