Previous investigators have reported that amount and quality of sleep are reduced in the shiftworker. The finding that night and morning shifts lead to shortened sleeping hours is replicated in this study. Overall sleeping time, however, was not found to be different for workers on different shift schedules or for shiftworkers and nonshiftworkers. The correlation between length and quality of sleep was very low. Length of sleep was not predicted well by factors such as stress at work, noisiness of sleeping room, drinking coffee, and smoking cigarettes, although these and similar predictors were strongly related to quality of sleep. Shiftwork was found to have a consistent effect on quality of sleep, even when other variables were controlled. © 1984 The American College of Occupational and Environmental Medicine.