Dynamic Change of Night Shift Loading and Sleep Quality

Abstract

ISEE-0266 Abstract: Shift work is related to many health problems and sleep disturbance is one of them, especially for those working night shifts. Hence, we evaluated the association between night shift and sleep quality among registered nurses, whose work usually includes night shift rotation schedule. This study recruited 458 nurses with night shift working schedule registered in Kaohsiung area, Taiwan. They completed two similar structured questionnaires in 2005 and 2006. The data included demographic characteristics, status of work schedule in the previous two months, and sleep conditions evaluated by the Pittsburgh Sleep Quality Index (PSQI). In 2005 and 2006, averaged scores were 8.79 and 8.76. Among the 458 nurses, 79.3% and 77.9% had a bad sleep quality, defined as PSQI above 5. We found that having done less than 7 night shifts in the previous two months resulted in better sleep quality in 2005 and 2006 compared to rotas with more night shifts, with the PSQI score 8.33 and 8.24; whereas the PSQI scores were 9.02 and 8.94 for 7–14 night-shift, and PSQI scores were 9.26 and 9.54 for those with over 14 night-shift (P for trend: 0.027 for 2005 and 0.002 for 2006). Between these two surveys, increasing number of days of night shift during the follow-up period was significantly associated with detrimental change in sleep quality. For those with increased number of night shift days, the PSQI score increased from 8.81 to 9.56 (P = 0.0131). However, for those with decreased number of night shift days in between the two surveys, sleep quality did not improve significantly (PSQI score 8.87 in 2005 and 8.79 in 2006, P = 0.7818). Although the night shift arrangement is unavoidable, the number of night shift days has a negative effect on sleep quality and this does not improve easily after a decrease in night-shift days. At one year follow up, the effect of increasing number of night shift days may be to aggravate sleep quality, but there is no improvement following a decrease in number of night shift days.