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Journal of Occupational & Environmental Medicine:

Subjective and Objective Evaluation of Sleep and Performance in Daytime Versus Nighttime Sleep in Extended-Hours Shift-Workers at an Underground Mine

Hossain, Jamil L. MBBS, MSc, RPSGT; Reinish, Lawrence W. MD, FRCPC; Heslegrave, Ronald J. PhD; Hall, Gordon W. MD, CCBOM; Kayumov, Leonid PhD, DABSM; Chung, Sharon A. PhD; Bhuiya, Pintu MBBS, RPSGT; Jovanovic, Dragona BSc, RPSGT; Huterer, Nada MD, RPSGT; Volkov, Jana MD; Shapiro, Colin M. MBBCh, PhD, FRCPC

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Extended hours of shift work has the potential for adverse consequences for workers, particularly during the nightshift, such as poorer sleep quality during the day, increased worker fatigue, and fatigue-related accidents and decreased work performance. This study examined subjective and objective measurements of sleep and performance in a group of underground miners before and after the change from a backward-rotating 8-hour to a forward-rotating 10-hour shift schedule. The purpose of this study was to evaluate the short- and long-term impact of a shift schedule change on sleep and performance. The results demonstrated improved subjective and objective measures of sleep and performance on the new 10-hour nightshift schedule. The 10-hour nightshift workers subjectively reported more refreshing sleep, fewer performance impairments and driving difficulties than 8-hour nightshift workers. The results of the objective measures of sleep and performance on the 10-hour nightshifts were overall similar or possibly better than those measured on the 10-hour dayshifts. These are some of the first data to suggest that a nightshift that does not encompass the entire night period could have significant benefits to shift-workers. We suggest that these benefits are mostly the result of the timing of the new nightshift start and end times rather than other shift-schedule factors.

©2004The American College of Occupational and Environmental Medicine


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