Night-Shift Work Linked To Increased Mortality In Nurses

Eva Schernhammer, MD, DrPH Associate Professor of Medicine Brigham and Women's Hospital and Harvard Medical School Associate Professor of Epidemiology Harvard School of Public Health Channing Division of Network MedicineMedicalResearch.com Interview with:
Eva Schernhammer, MD, DrPH

Associate Professor of Medicine
Brigham and Women’s Hospital and Harvard Medical School
Associate Professor of Epidemiology
Harvard School of Public Health
Channing Division of Network Medicine

Medical Research: What is the background for this study? What are the main findings?

Prof. Schernhammer: The study is an observational cohort study of over 70,000 registered nurses from within the US who reported the total number of years they had worked rotating night work and were followed for several decades. We examined overall mortality in these women, and observed significantly higher overall mortality, as well as higher mortality from cardiovascular disease in women with several years of rotating night shift work, compared to nurses who had never worked night shifts. There was also some suggestion for modest and non-significant increases in mortality from a few cancers. The study is unique due to its size, the fact that all participants were nurses (eliminating potential biases arising from differing occupational exposures), the long follow-up, and the possibility to take into account most known risk factors for chronic diseases that we currently know of (all of this information has been collected regularly and repeatedly). 

Medical Research: What should clinicians and patients take away from your report?

Prof. Schernhammer: We are currently studying what night workers could do to lower the potential health risks they face. Various approaches are being explored by us and others, from using light interventions to sleep aids to matching individuals’ shift schedule to their inherent chronotype. However, for now, and given none of the above have been proven yet to be successful, night workers may just try to eliminate as many other lifestyle-related risk factors as possible, e.g. quit smoking, exercise regularly, eat healthily, maintain a healthy weight, get your regular screening (breast, colon, etc.).

Medical Research: What recommendations do you have for future research as a result of this study?

Prof. Schernhammer: To some degree this suggests that, because of the possibly detrimental effects of night work, night workers (including their employers) may want to pay particular attention to keeping their health in check. Hopefully – in the near future – we can also recommend additional measures that alleviate some of the strain that night work imposes on the circadian system (e.g., as said above, by matching individuals’ shift schedules – to the extent possible – with their inherent sleep preferences (e.g. whether someone tends to be more of a night owl, or morning type – lark), and future studies are needed to explore this.

Citation:

Total and Cause-Specific Mortality of U.S. Nurses Working Rotating Night Shifts

 Fangyi Gu, MD, ScD Jiali Han, PhD Francine Laden, ScD An Pan, PhD Neil E. Caporaso, MD Meir J. Stampfer, MD, DrPH Ichiro Kawachi, MD, PhD Kathryn M. Rexrode, MD, MPH Walter C. Willett, MD, DrPH Susan E. Hankinson, ScD Frank E. Speizer, MD Eva S. Schernhammer, MD, DrP H

American Journal of Preventive Medicine

Available online 6 January 2015

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