Fatigue is the silent killer
Employers and supervisors should be aware of the dangers of fatigue, which is a growing workplace hazard.
Fatigue is the state of feeling very tired, weary or sleepy from insufficient sleep, prolonged mental or physical work, or extended periods of stress or anxiety.
Boring or repetitive tasks can intensify feelings of fatigue. Fatigue can be described as either acute or chronic. Employers and supervisors should be concerned about the impact of fatigue in the workplace as it can be considered a form of impairment, making fatigue a workplace hazard.
Consider this hypothetical scenario:
A student was offered employment at an employer’s site that required him to commute 2.5 hours each way. After working two-day shifts, the student was assigned to work the night shift to cover for another worker.
At the end of his eighth consecutive shift, he left the worksite and started to drive home. Shortly after, his car left the road and he was killed in the crash. The police report concluded that he failed to negotiate a curve and was likely asleep or looking away from the road at the time of the accident.
From a human factor perspective, what can we learn from this incident?
Most people need 7.5-8.5 hours of sleep each day. Sleep loss built up slowly over several nights can be as harmful as sleep loss in one night.
Both produce a decline in performance, such as slower reaction times, failure to respond to changes and the inability to concentrate and make reasonable judgments.
Research that tested a fatigued state from continuous hours of wakefulness against blood alcohol levels concluded that:
- 17 hours awake is equivalent to a blood alcohol content of .05
- 21 hours awake is equivalent to a blood alcohol content of .08
- 24-25 hours awake is equivalent to a blood alcohol content of .10.
In addition to fatigue caused by shortened periods of sleep, the quality of sleep during the day is not the same as during the night. People have a natural tendency to be awake during the day.
Every person has a circadian rhythm – an internal biological time clock. This rhythm follows body temperature and changes our level of mental alertness.
Typically, in a 24-hour period, our alertness is reduced between the hours of 3:00 and 5:00 during the day and the night. So, during night shifts, workers are fighting against their natural rhythm to stay awake at a time when they would naturally sleep.
We live in a society where fatigue is a serious workplace health and safety issue. Everyone can become fatigued. The best way to cope with fatigue is to prevent its onset. The continuous number of hours worked and the time of day worked (day versus night shifts) need to be considered when developing work schedules.
The potential for accumulated or sudden sleep loss should also be considered. To manage fatigue, the entire time a worker has to be awake should be considered, not just the time spent working.
For example, the time spent commuting, especially for those who drive a long distance after leaving night shift. This time may add to an already long shift and increase the likelihood of fatigue impairment.
It is important to understand and recognise the signs and symptoms of fatigue and adopt prevention strategies that minimise the risk of accidents.
Worksafe WA have a Code of Practice for Working Hours which addresses issues that might potentially arise in some arrangements, such as extended hours, shift-work and on-call work.
It brings together a range of recognised workplace hazard factors that must already be addressed, as far as practicable, where there are occupational safety and health risks.