Hours of Work and Shiftwork

First the time elements of n working day, the duration of working time and the time positioning of working time are treated under ergonomics aspects, Second the reasons for shiftwork, different types of shiftwork as well as effects on health and on family and social life are discussed. Finally the following physiological criteria for optimal shift-schedules are presented: (1) Single night shifts are better than consecutive night shifts. (2) At least 24 hours free time should be allowed after each night shift. (3) The cycle of a shift system should not he too long. (4) The length of the shift should be related to the type of work. (5) In connection with continuous shiftwork as many free weekends as possible should be arranged.