[Characteristics of main and additional sleep time in workers on rotating shifts]

Various sleep characteristics were examined among rotating shift workers (n = 603) and control workers (n = 113). The results showed the shift workers to have poorer sleep quality than the control group. In addition their main sleep episode was shorter on morning shift and longer on days off in comparison to controls. Shift workers' main sleep length and frequency of napping were affected by the situation in which they were taken (morning, afternoon, night shift or days off). In the group of shift workers the short main sleep episode on morning and night shifts was compensated by longer sleep on afternoon shift and days off. The short night shift sleep was additionally compensated by napping. However, naps taken on the morning shift did not prove to be compensatory. The length of the main sleep episode was affected by the situation in which sleep was taken also in the control group of workers. In this group only the longer main sleep episode on days off appeared to have a compensatory function for the short main sleep on working days. The relationship between sleep quality and main sleep duration was determined by the situation in which sleep was taken, while the relationship between sleep quality and napping was established only for the control group of workers.