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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: March 2004 - Volume 46 - Issue 3 - pp 212-226
CME ARTICLES: CM: CME Article #2

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.

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