Shiftwork - health effects

There is increasing evidence becoming available that shiftwork can lead to very serious consequences. Night work and shiftwork have been linked to serious conditions from cancer to heart disease. Fatigue can be deadly. The hours we work are a crucial health and safety issue.

In the UK summer of 2009, the TUC'sHazards Magazinedid aspecial report on Shiftwork:While you were sleeping. The report begins:

Shiftwork and work at night has been linked to a wide range of health problems, including breast cancer (1), prostate cancer (2), non-Hodgkin’s lymphoma (3), heightened accident risk (4), heart disease risk factors (5) and pregnancy problems (6). There is emerging evidence that these health effects combined make shiftworkers, particularly women shiftworkers, far more likely to take early ill-health retirement (7).

The report provides a great background on what are non-typical hours, how shiftwork affects the body, the evidence of links between shiftwork and breast cancer, and heart disease, and reproductive health. It provides some advice on what to do at the workplace, facts and fiction around shiftwork and an "action plan" for reps. In addition, all the information is referenced.


1. Sarah Megdala and others. Night work and breast cancer risk: A systematic review and meta-analysis, European Journal of Cancer, volume 41, issue 13, pages 2023-2032, 2005.

2. Tatsuhiko Kubo and others. Prospective cohort study of the risk of prostate cancer among rotating-shift workers: Findings from the Japan Collaborative Cohort Study, American Journal of Epidemiology, volume 164, pages 549-555, 2006.

3. T Lahti and others. Night-time work predisposes to non-Hodgkin lymphoma, International Journal of Cancer, volume 123, pages 2148–2151, 2008.

4. Kenneth N Fortson. The diurnal pattern of on-the-job injuries, Monthly Labor Review, pages 18-25, September 2004 [pdf].

5. Y Fujino and others. A prospective cohort study of shift work and risk of ischemic heart disease in Japanese male workers, American Journal of Epidemiology, volume 164, pages 128-135, 2006.

6. Lisa A Pompeii others. Physical exertion at work and the risk of preterm delivery and small-for-gestational-age birth, Obstetrics & Gynaecology, volume 106, pages 1279-1288, 2005 [abstract or pdf].

7. Finn Tüchsen, Karl Bang Christensen, Thomas Lund, and Helene Feveile. A 15 year prospective study of shift work and disability pension, Occupational and Environmental Medicine, volume 65, pages 283–285, 2008.

September, 2010 
The Canadian Institute for Work and Health, an independent not-for-profit organisation whose mission is to conduct and share OHS research, has published an issues briefingon the impact of shiftwork on health. The research has noted some concerns involved with shiftwork.

The key messages from the research are:

  • People who work night shifts are likely to have shorter sleep duration and/or poorer sleep quality than regular day workers.
  • Long-term exposure to night shift work may elevate the risk of breast cancer. There are also findings pointing to an elevated risk of colorectal cancer.
  • Some studies indicate an elevated risk of preterm delivery, gastrointestinal disorders and mental health problems among shiftworkers.
  • Research findings regarding a causal link between shiftwork and heart disease are inconsistent.
  • Shiftworkers, especially those working at night, face a higher risk of workplace injury than regular day workers.
  • Promising approaches to mitigate the adverse effects of shiftwork include restricting successive evening or night.
  • Shifts to three shifts, limiting weekend work, moving from backward to forward shift rotation and using a participatory approach to the design of shift schedules.
  • More research is needed to resolve some of the questions regarding the health effects of shift work, and to investigate the impact of interventions designed to mitigate the adverse consequences of shiftwork on health.