Experimental evaluation of frequent eight-hour versus less frequent longer night shifts

Abstract

In view of the increasing evidence that performance varies as a function of the particular shift worked, it seems reasonable to assume that a shift of shorter length is more favourable in terms of preventing large performance decrements. In industry, however, a nightshift of longer duration is often proposed on the grounds that rotation with long-hour shifts makes the formation of teams easier and gives the worker holidays of considerable length, while at the same time reduces commuting difficulties (Menzel, 1962; Kogi, 1962). Thus, a wider view needs to be taken, and more detailed studies on the organization of sleep-waking cycles may be necessary to solve this problem. One must also take into account the current trend in shift rotation that attempts to avoid large disturbances of the basic biological rhythm (Andlauer, 1972). In the present experimental study, we tried to clarify the nature of the performance decrement of night workers in hospital wards engaged in nightshifts of different length, by comparing the normal 8-hour three-shift system with experimental routines involving either 12-hour or 16-hour nightshifts.