Shift Work and Fatigue

Nearly 15 million full-time workers across the U.S. work shifts outside the traditional eight-hour daytime schedule. While your business may require these later shifts to meet customer needs and delivery deadlines, long work hours and poor scheduling can lead to occupational fatigue and increase the risk of employee injuries.

Occupational fatigue is associated with extreme physical or mental tiredness that occurs on the job. Research conducted by Liberty Mutual has shown occupational fatigue to be the result of multiple factors that include sleep homeostasis, or the body’s tendency to make up for lost sleep; circadian influences; and the nature of the tasks performed. 

Everyday examples of these factors include the following: 

  • Long or unusual work hours
  • Insufficient time off between shifts
  • Inadequate rest and sleep
  • Excessive stress
  • Prolonged physical or mental activity
  • Repetitive work tasks
  • Chronic medical conditions
  • Insufficient rest breaks during the shift 

Each of these factors, particularly when combined, can lead to impaired performance in the form of reduced cognitive abilities, slowed reaction times, and increased errors in judgment. In addition to reducing productivity and quality, these conditions can seriously compromise safety, especially in jobs involving high-risk tasks such as operating machinery, vehicles, or heavy equipment. 

Many companies attempt to lower worker fatigue by controlling only the total number of hours worked in a day, week, or month. However, focusing on other shift-work factors may have a greater impact on safety and should also be considered. 

Based on research conducted by Liberty Mutual and Paris Descartes University, the following shift-scheduling practices can help reduce occupational fatigue and its associated risks: 

  • Schedule day (morning) shifts rather than afternoon or night shifts, if possible.
  • Limit consecutive day shifts to five or six, night shifts to four.
  • Provide frequent rest breaks. (For many kinds of work, hourly breaks are appropriate. However, more frequent breaks are recommended for highly repetitive or strenuous work.)
  • Schedule work so that all workers have at least two consecutive rest days, with Saturday or Sunday as one or both of the days off.
  • Keep schedules regular and predictable.
  • Alternate weeks of overtime with weeks of normal time. 

By keeping these practices in mind, you can make more informed scheduling decisions and promote a safer workplace. 

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The illustrations, instructions, and principles in this material are general in scope and, to the best of our knowledge, current at the time of publication. No attempt has been made to interpret any referenced codes, standards, or regulations nor to identify all potential risks or requirements.