The Journal of Science of Labour
Online ISSN : 2187-2570
Print ISSN : 0022-443X
Short Communications
Sleep Architecture of Nocturnal Naps Evaluated by a Non-contact Sheet Sensor (Nemuri-Monitor®) and Sleep Regulation on the Duty Period of Hospital Nurses Engaged in a 14-hour Night Shift
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2013 Volume 89 Issue 6 Pages 206-212


The criteria set by the Japanese Nursing Association (2013) for improving the conditions of night and shift work of nurses according to the principles recommended by Knauth and Rutenfranz are expected to become a cornerstone of the efforts to improve working conditions for nurses. However, the 16-hour night shift already in place poses practical obstacles spreading the use of an ergonomic 8-hour night shift which would require drastic changes in the current shift systems. Recently, an interim strat egy is instituted by applying a night shift of 12 to 14 hours that allows for naps (90 min) during the shift. Therefore, in this study, we investigated the relationship between the sleep architecture of naps during the night shift working on a 14-hour night shift (19:00-09:00) and that of sleeps preceding the night shift. We used new devices deployed under mattresses to evaluate the sleep architecture (Nemuri monitor; AISIN SEIKI Co., Ltd). The participants were 30 nurses assigned to the night shift in the internal ward. Their average age was 26.7 years. The three nurses assigned to each night shift took their naps in succession, with the first nap (0:00-1:30), the second nap (1:30-3:00) and the third nap (3:00-4:30). We measured the naps for 139 person-days. And we obtained data on sleep during the preceding off night and daytime sleeps just before the night shift through the sleep logs maintained by the subjects.
There were no significant differences in the three nap conditions excepting for Work after sleep onset (p=0.002 between the first nap and the third nap). We found no statistically signifi cant differences for slow-wave sleep perhaps a result of the strain for the nap (e.g. rumination and apprehension) imposed on the nurses by their duties. There was a negative relationship between sleep during the preceding off-night and daytime sleep just before the night shift (p < 0.001, r=-0.3). The participants tended to postpone the bedtime on the off-night before their assigned shift to ensure a long sleep during the daytime before the night shift. On the off-night preceding the day of the assigned night shift, sleep began between 01:00 and 01:59 or between 02:00 and 02:59 in the largest number of participants (26.0% each), whereas it was started after 04:00 in as many as 11.0% of the participants. Nurses, consequently, tended to sacrifice personal life and their sleep schedule to accommodate work duties, since various events, specificity as “Human Care Work”, including any sudden change in patient conditions or procedures related to a deceased patient, might have precluded the nap during night shift.

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© 2013 The Institute for Science of Labour
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