Alertness of night nurses: two shift systems compared.

The alertness of hospital trainee nurses during their night shift work was assessed by recording performance at night on an arousal-sensitive unprepared simple reaction time task. One group carried out a number of separate weeks on night shift throughout their three-year course. Here performance fell from first to seventh day of the week on night shift, implying progressive sleep deprivation. Another group covered their night work by a single three-month 'permanent' night shift of four (or three) nights on and three (or four) days off each week. Here initial performance level fell by the 45th night but had returned to normal by the last (90th) night. In both systems individuals varied considerably in their ability to maintain performance during sustained night work. These results strengthen the case for permanent night shifts, with careful selection of personnel, as a means of organizing night nursing in hospitals.