MODULE 7: PSYCHOSOCIAL ISSUES AND OTHER MISCELLANEOUS TOPICS IN OCCUPATIONAL AND ENVIRONMENTAL HEALTH
SECTION 7: SHIFTWORK AND HOURS OF WORK
Introduction
 

OBJECTIVES
By the end of this Section you should:
    SECTION OBJECTIVES
  1. understand the health impacts and dangers of shiftwork;
  2. know the different rotation systems in shiftwork;
  3. understand individual strategies that can be employed in shiftwork;
  4. know the health contraindications for shiftwork.

INTRODUCTION:

Possibly since the earliest pre-capitalist and capitalist societies, hours of work have never been restricted to daylight hours only. Workers have been either forced, coerced or given significant financial incentives to work into the long hours of the night. While today there are many work activities which necessitate night work (for example, emergency health care services), the persistent drive for increasing productivity in modern society has ensured that many industries work around the clock.

The fundamental problem with shiftwork is that human beings have evolved into having diurnal "body clocks" (circadian rythyms) - physiologically our body systems expect us to be working during the day, and resting when the sun goes down. Shiftwork creates an imbalance in the diurnal rythym of our bodies, which can sometimes result in adverse health outcomes.

Broadly defined, shiftwork is work that does not take place usually between the hours of 07h00 and 18h00. This will include workers rotating over periods of time from day to night shift, but will also include workers on permanent nightshift (for example, nightwatchmen) without any shift rotation.

Different assessments suggest that anything between 10 - 25% of the workforce may work shifts, implying that it is a major occupational health issue.

A useful review reference is the article by Harrington in Occupational and Environmental Medicine.

REFERENCES:

  1. CC Maldonado, L Tanchel, FC Baker. The 24 hour society: focus on shiftwork and sleepiness. OHSA Vol 5.3 May/June 1999:LINK
  2. Work shift duration: a review comparing eight hour and 12 hour shift systems. Occupational & Environmental Medicine. 55(4):217-29, 1998 April.
  3. Effects of direction of rotation in continuous and discontinuous 8 hour shift systems. Occupational & Environmental Medicine. 57(10):678-84, 2000 October.