The effects of frequently rotating shiftwork on sleep and the family life of hospital nurses

The effects of three frequently rotating shifts in an irregular sequence on the daily activities of 239 Japanese female hospital nurses were studied by the time-budget method. The nurses recorded their daily activities for several consecutive days. The questionnaire was returned by 80.8% of the participants, and recordings of 1016 days were analysed. A two-way analysis of variance clarified that the shift combination influenced the daily activities. The most distinct result was that nurses spent significantly more time on free-time activities on the day when they worked the night shift followed by the evening shift than they did on the day when they worked any other shift combination. Nurses offset sleep deprivation either by sleeping during the day before and after working the night shift (82-100%) or by sleeping 2 to 4 h later in the morning after working the evening shift and on days off. There was a strong positive correlation between total sleep time (including day sleep) and the length of the interval between two consecutive shifts (r = 0.95, p < 0.001). This result suggests that more than 16 h between work shifts is required to allow more than 7 h of total sleep time. In an analysis by household status, nurses who had young children (average age, 2.8 years) slept less and spent less time on free-time activities than did other nurses.