The many meanings of sleep

Abstract Reductions in sleep are concomitant with night shift work. Data are presented showing that these robust differences in sleep are even present in experienced permanent night shift workers who most prefer to work nights. A model is presented which relates these reductions to chronic sleep deprivation. This, in turn, may be associated with performance decrements, and lead to accidents and illness. Better work schedule selection, worker training programs, and preventive medical action are unproven but promising approaches to overturning this model.