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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

Journal of Occupational & Environmental Medicine:
CME ARTICLES: CM: CME Article #2
Abstract

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.

Author Information

From the Sleep Research Laboratory and the Department of Psychiatry (Dr Hossain), Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada; the Department of Psychiatry (Dr Reinish), University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada; the Research Ethics Board (Dr Heslegrave), University Health Network, Toronto, Ontario, Canada; the Department of Occupational Health and Hygiene (Dr Hall), Falconbridge Ltd., Toronto, Ontario, Canada; the Department of Psychiatry (Dr Kayumov), University of Toronto, Toronto, Western Hospital, University Health Network, Toronto, Ontario, Canada; the Sleep Research Laboratory and Department of Psychiatry (Dr Chung), Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada; the Sleep and Alertness Clinic (Drs Bhuiya, Jovanovic, Hunter, and Fishyenko), Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada; and the Department of Psychiatry (Dr Shapiro), University of Toronto, and the Sleep Research Laboratory, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.

Address correspondence to: Colin M. Shapiro, MBBCh, PhD, FRCPC, Professor of Psychiatry, University of Toronto, Director, Sleep Research Laboratory, Toronto Western Hospital, University Health Network, ECW-3D, 399 Bathurst Street, Toronto, Ontario, M5T 2S8, Canada; E-mail: colin.shapiro@uhn.on.ca.

©2004The American College of Occupational and Environmental Medicine