Fatigue Issue 9: Fatigue and the Effects on Work

By Ganymede

​Fatigue Issue 9 - Fatigue and the effects on work

Research reveals that, although the effects are different for different people, when a person is sleep deprived and/or fatigued, performance is affected and errors are more likely, which can increase a worker’s hazard exposure.

In particular, studies report the effects that can be reduced include:

  • decision making ability

  • ability to do complex planning

  • communication skills

  • productivity or performance

  • attention and vigilance

  • ability to handle stress on the job

  • reaction time - both in speed and thought

  • memory or the ability to recall details

  • response to changes in surroundings or information provided

  • ability to stay awake (e.g., falling asleep while operating machinery or driving a vehicle).

In addition, it may mean an increase in:

  • tendency for risk-taking

  • forgetfulness

  • errors in judgement

  • sick time, absenteeism, rate of turnover

  • incident rates.

Poorly designed shift-working arrangements and long working hours that do not balance the demands of work with time for rest and recovery can also result in fatigue, accidents, injuries and ill health.

Studies have reported that night workers get about 5 to 7 hours less sleep per week than those who work during the day. Sleep deprivation and fatigue therefore pose particular risks for shift-based work, and in safety-critical industries like the railway, with some research studies demonstrating that workers who have had less than 5 hours sleep before work or have been awake for more than 16 hours have a significantly increased chance of making mistakes.

Further, the number of hours awake can be similar to blood alcohol levels, with one study reporting the following:

  • 17 hours awake is equivalent to a blood alcohol content of 0.05

  • 21 hours awake is equivalent to a blood alcohol content of 0.08

  • 24 - 25 hours awake is equivalent to a blood alcohol content of 0.1011.

Remember the legal blood alcohol content for driving is 0.05 in Scotland and 0.08 in England and Wales.
Fatigued shift workers may perform less well than those working standard daytime hours, especially during periods of low alertness. The consequences of this could range from relatively minor events to serious accidents, and the risk of errors, accidents and injuries has been found:

  • ​to be higher on the night shift

  • to rise with increasing shift length over eight hours

  • to increase over successive shifts, especially if they are night shifts

  • to increase when there are not enough breaks.

Signs and symptoms of fatigue to look out for (in yourself and colleagues) include:

  • weariness/tiredness

  • irritability

  • reduced alertness, concentration and memory

  • lack of motivation

  • depression

  • giddiness

  • loss of appetite y increased susceptibility to illness.

The lowest levels of performance tend to occur during the period of 03:00 and 06:00 and that many fatigue-related accidents had occurred during the early morning.

If you have any questions regarding the topics covered in our Fatigue series, please don't hesitate to get in touch with our HSEQ team on 0333 011 2048 who will offer you support and guidance.