Shift-work and extended hours of work

Shift-work and extended hours working hours are increasing in many industries and organisations in Australia.  It is estimated that about 30% of employees are involved in work outside of regular daytime hours. 

Workers on shift-work face a number problems: increased levels of fatigues; increased risks to their health; negative effects on their family and social lives.

The body is synchronised to night and day by a small part of the brain known as the circadian clock. Body functions - such as heart rate, blood pressure, temperature, digestion and brain activity - fluctuate over each 24-hour period, under the guidance of the circadian clock.

Increased risks

A person working the night shift is at greater risk of various disorders, accidents and misfortunes, including:

  • Increased likelihood of weight problems and obesity
  • Increased risk of cardiovascular (heart) disease
  • Increased risk of cancer, particularly breast cancer - IARC has categorised shift-work that involves circadian disruption as a Group 2A carcinogen - ie probably carcinogenic to humans 
  • Increased risk of gastrointestinal problems, such as constipation, stomach discomfort and peptic ulcers
  • Potential problems during pregnancy
  • Higher risk of motor vehicle accidents and work related accidents
  • Higher risk of mood changes
  • Increased likelihood of family problems, including divorce
  • The sleep deprivation, which can be caused by shiftwork, may increase the risk of epilepsy in pre-disposed people
  • Shiftworkers with diabetes can experience difficulties in controlling their blood sugar levels.

Danish research completed in 2007 also suggests that shift work may increase the risk of enforced early retirement in women.

Shift-work and car accidents

Shift-work is the greatest sleep-related factor contributing to motor vehicle accidents, an Australian study (Prevalence of sleepiness in surviving drivers of motor vehicle collisions) has found.  The lead author of the study said that sleepiness, particularly related to shift-work, needs to be emphasised as a risk factor for motor vehicle collisions.  He added that the results showed employers need to look after shift-workers better — suggesting 10-hour breaks between shifts, limited weekly rosters and taxis home from work.

Sleep problems

Shift-workers tend to get two to three hours less sleep than other workers. They often sleep though the day in two split periods, a few hours in the morning and then an hour or so before going to work at night. Night workers can find it difficult sleeping during the day, as it is difficult to keep the sleep environment dark as well as free of noise.

See Also

Last updated April 2016

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