15 – 20 per cent of people in industrialised countries are doing night work, weekend work or other types of shiftwork. This can result in fatigue which increases the risks of accidents occurring.
The fatigue levels of personnel have been a contributing factor in some very serious industrial accidents.
After having been awake for 17 hours straight a persons driving ability is equal to that of a person with a 0.05 blood alcohol level. Being awake for 24 hours is equivalent to a blood alcohol level of 0.1, double the legal limit.
What is fatigue?
Fatigue is a general term used to describe the feeling of being tired, drained or exhausted. It is mental or physical exhaustion that stops a person from being able to function normally.
Sign and symptoms of fatigue:
- poor judgment
- anxiety, irritability, depression & mood disturbances
- slower reactions times
- impaired hand-eye coordination
- decreased skills, such as in vehicle control
- reduced attention/motivation
- decreased short term memory
- increased risk taking behaviour
The causes of workplace fatigue
Shift work –
In terms of work hours, shift work is defined as work that starts before 8.00am and finishes after 6.00pm. A biological definition of shift work would be any work pattern that causes a change in normal sleep patterns. Shift work (in particular night work) can be a powerful cause of fatigue when it:
- limits a person’s opportunities to get adequate sleep
- requires them to work in the early hours of the morning, when people are normally at their sleepiest and least functional.
Extended work hours –
Shifts that last longer than 8 hours are classed as long or extended. People may work long hours on a short-term basis to deal with a major emergency or an unexpected situation, or they may work long hours regularly for financial or other reasons. The effects of working long hours depend on how long the work periods are, how often they occur, and at what time of day.
Sleep restriction (having several hours less sleep than needed) has clear, negative effects on human performance. It suppresses the immune system, increases appetite, and makes the body increasingly resistant to insulin. Several nights of restricted sleep can create a ‘sleep debt’, which has clear effects on performance. The combined effects of sleep restriction and extended hours of work have a short-term impact on performance, and in the long term may affect cardiovascular health, mental health, safety, and productivity.
Night work –
All the statements above refer to day work. Working at night has a greater impact than working the same number of hours in the daytime, and the impact is even greater when the work hours are extended.
On average, shift workers lose 1-1.5 hours of sleep for each 24-hour period. This builds up a sleep debt of 6 hours after 4 nights. Working more than three or four night shifts in a row is likely to cause a significant sleep debt, with serious consequences for safety. Night-work hours should be limited. For example, an employment contract for employees doing work where risks of errors are high could state:
The total number of hours an employee may work between midnight and 6.00am is limited to 18 over three days, after which they must have two full nights off for sleep.
Your body clock
Human beings are day oriented and we are designed to work in the daytime and sleep at night. Our internal body clock helps control variations of mental and bodily functions over a 24 hour period. Body temperature, heart rate, blood pressure and adrenaline production normally rise during the day and fall at night. It is these changes which affect behaviour, alertness, reaction time and the mental capacity of all people by varying degrees. Exactly what makes us fall asleep is still not completely understood however it seems that the fall in our core temperature plays a role in making us sleepy. Similarly, the rise in core temperature at the beginning of the day helps to wake us up. Because of this daily temperature change it is often harder for us to stay awake as night progresses.
Where fatigue may adversely affect a persons ability to work safely it must be identified, assessed and controlled like any other hazard in the workplace.
Fatigue management
It is important to be aware of the way different rosters can increase your chance of fatigue if not managed.
- regular day shifts carry the lowest risk of fatigue
- risks increase with afternoon shifts as often you can not get to bed, and to sleep until after midnight
- night shifts carry the highest risk as this is when the body is most ready for sleep
As an employee it is your responsibility to be fit for work. This means not only turning up in a sober drug free state, but also well rested.
Some administrative controls to address work related fatigue issues are by –
- decreasing the length of the work cycle
- changing the direction of rotation
- decreasing the duration of shifts
- increasing daily rest periods
- decreasing overtime
- increasing the regularity of the rosters
Basic principles of fatigue management
A number of basic principles apply when developing a fatigue management system. The following are detailed in the code of practice and should be considered as the basis for most systems.
Give an employee at least 24 hours notice to prepare for a working time period of 14 hours or more.
- Minimise irregular or unfamiliar work rosters.
- Operate flexible schedules to allow for Short Break Time.
- Develop a written policy on fitness for duty in consultation with employees and unions.
- Require regular assessment of an employees health by a suitably qualified medical practitioner.
- Ensure that the medical assessment includes consideration of sleep disorders and other fatigue related conditions.
- Identify health problems that affect the ability to work safely e.g. Diabetes.
- Provide appropriate employee assistance programs if necessary and practicable.
- Provide employees with information and assistance to promote management of their health.
- Ensure employees are counselled regarding off shift activities i.e. to avoid excessive drinking, fatty foods and moonlighting. Exercise is a good idea.
Tips for managing fatigue in shift work
- have a short sleep before your shift
- do some moderate exercise before starting work, which helps to increase your alertness during the shift
- have bright lighting
- vary your work at the times you feel most drowsy, if possible
- walk around during breaks
- keep in contact with co-workers as this helps you both stay mentally alert
- consider using public transport or taxis rather than driving if possible, or share the driving responsibility with a co-worker
- try to follow a similar routine to the one you follow before a normal nights sleep
- make the environment favourable for sleeping e.g. ask family or flatmates not to disturb you, turn you mobile off, pull the curtains over your window
Despite the fact that workplace fatigue is four times more likely to contribute to workplace impairment than drugs or alcohol, many organisations remain unaware of the significant impact fatigue has on employee health, workplace safety and productivity.
In an environment in which many industries are required to run 24 hour operations to meet customer demand and in which 17 percent of Australian employees work night shifts, failure to effectively manage workplace fatigue can be costly.
Acknowledgments
Better Health Channel – Fatigue