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Switching to Daylight Saving Time and work injuries in Ontario, Canada: 1993–2007
  1. Sara Morassaei1,
  2. Peter M Smith1,2
  1. 1Institute for Work & Health, Toronto, Canada
  2. 2Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
  1. Correspondence to Sara Morassaei, Institute for Work & Health, 481 University Ave, Suite 800, Toronto, ON M5G 2E9, Canada; smorassaei{at}


Objective To examine whether switching to and from Daylight Saving Time (DST)—1 h shift forward in the spring and 1 h shift back in the autumn—is associated with an increase in work injuries.

Method Data on work-related injuries were obtained from compensation claim records from the Ontario Workplace Safety & Insurance Board for the period 1993–2007. A Poisson regression model was run separately comparing the number of no lost time claims and lost time claims during the week of DST change with the week following DST change, and the week preceding DST change. We also examined if differences in the relationship between DST and work injury claims were present across industry, age, gender and job tenure groups.

Results The results of our regression model did not show an increase in the incidence of work injury claims in the days immediately following the spring shift to DST. There was a significant decrease in the number of claims on Thursday, Friday and Saturday following the spring transition to DST. However, this decline was solely due to the years when Good Friday occurred during DST week (1993, 1998 and 2004) when fewer people are at work. For the autumn transition from DST, no evidence was found that the gain of 1 h sleep results in a decrease or increase in work injury claims.

Conclusion Our findings show that the shift to and from DST had no detrimental effects on the incidence of claims for work injuries in Ontario, Canada.

  • Work injury
  • sleep
  • Canada
  • public health
  • injury
  • accidents

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  • Funding Peter Smith is supported by a New Investigator Award from the Canadian Institutes of Health Research.

  • Competing interests None.

  • Ethics approval The University of Toronto, Health Sciences Ethics Committee approved the secondary data analyses.

  • Provenance and peer review Not commissioned; externally peer reviewed.