Work-related fatigue

Fatigue is more than feeling tired and drowsy. In a work context, fatigue is a state of mental and/or physical exhaustion which reduces a person’s ability to perform work safely and effectively.

It can occur because of prolonged mental or physical activity, sleep loss and/or disruption of the internal body clock.

Fatigue factors may be work related, non-work related or a combination of both and can accumulate over time.

In fact, studies have shown that 17 hours without sleep impairs your driving in the same way as having a blood alcohol level of 0.05 percent.

Fatigue has been found to have played a role in many well-known disasters such as the Chernobyl and Three Mile Island nuclear accidents, Exxon Valdez oil spill in Alaska and the 2010 Shen Neng Great Barrier Reef oil spill.

Managing Fatigue

Fatigue management is a shared responsibility between management and workers as it involves factors both inside and outside of work. Persons conducting a business or undertaking (PCBUs) are responsible for using a risk management approach to manage fatigue as outlined in the Work Health and Safety Act 2011.

For PCBUs the managing fatigue risks at work guide provides practical guidance on managing fatigue to ensure it does not contribute to health and safety risks in the workplace.

For workers the fatigue management guide provides guidance to manage fatigue so it does not contribute to health and safety risks in the workplace.

What can employers do to manage fatigue?

Extended hours of work

Extended work hours can affect the amount of time available for adequate sleep opportunity. It is important to monitor the amount of hours workers are doing each day. You can ensure workers aren’t required to work unnecessary extended hours by:

ensuring sufficient cover for workers who are on annual or sick leave
if overtime is necessary, plan for it so workers can schedule their activities around it

Where overtime is concerned:

Limit overtime to 4 hours for 8 hour shifts
Limit overtime to 2 hours for shifts longer than 10 hours.
Do not allow overtime for shifts longer than 12 hours.
Limit total hours per week to 55.
Have a policy on second jobs – ensure that the worker understands the obligation to get sufficient sleep and to be fit for duty.

Shiftwork

Shift work can be a contributing factor in work-related fatigue. Ensure the roster provides for a continuous 7 to 8 hours sleep in each 24 hours, and at least 50 hours sleep for every seven days.

If on a rotating three shift roster system, forward rotation (day, afternoon to night shifts) is tolerated better.

When determining your work schedules:

Limit number of consecutive night shifts to four to minimise accident risk.
End night shifts by 8am.
Ensure there is a minimum of 12 hours between consecutive shifts.
Ensure that roster allows for at least two full nights sleep after the last night shift.
Allow short naps of no longer than 15–20 minutes if it fits in with the type of work that is being done.
Consider whether 12 hour night shifts are really necessary.
Use additional control measures, such as two hourly breaks of at least 5 to 10 minutes duration.
Have a room for workers to sleep before commuting home.
Encourage healthy eating at work and provide access to healthy food options at work to minimise health risks.

Time of day

Minimise early morning starts before 6am as workers have less time to get adequate sleep – it is very difficult to go to sleep during the early evening (6–9pm) as our body clocks are set to alertness at that time.

Avoid more than five consecutive early morning starts.
Encourage carpooling or provide transport.

Roster and work design

Consider the following:

increasing supervision
allow regular breaks
length of shifts – depends on physical and mental load of the work
distribution of leisure time – allow for adequate rest and recovery
regularity of shift system – allows workers to prepare for work
previous hours and days worked – the effects of fatigue are cumulative, workers may have sleep debt due to the length of previous shifts. Giving workers two successive full days off within a seven day period allows them to catch up on their night sleep
type of work being performed – pay particular attention to the level of physical and/or mental effort required
time of the day when the work is being performed – avoid safety critical tasks during the early hours of the morning (3-5am).

Other factors to consider when managing fatigue

Sleep inertia

Sleep inertia can occur if a person is woken after sleeping for more than 40 minutes. They may be slow to respond, may feel drowsy and disoriented. It may it may take up to 30 minutes before complex tasks can be performed efficiently.

This has implications for safety when workers are on-call for emergencies. Suggested measures to control sleep inertia and the subsequent impairment in work performance include:

minimising naps taken at work that exceed 40 minutes
planning for recovery times of up to 30 minutes for workers who may be subject to sleep inertia, before they are to perform hazardous tasks.

Breaks

Time spent away from the work environment allows workers to recover from fatigue and improve performance, vigilance, safety and efficiency. For this reason breaks should be taken during work shifts, and should not be traded for an early finish time.

Occupational exposure levels

Extended working hours increase the risk of exposure to hazards such as noise, heat and chemicals and should be carefully monitored. National and international exposure standards are usually based on five 8 hour days per week. Workplaces where extended hours are worked will need to monitor exposure levels.

It is recommended that expert advice is sought in adjusting exposure levels, because the increased exposure of workers over a 10 hour shift may not be simply 1.25 times the exposure for eight hours. Models need to be used, to take into account the reduced recovery time after exposure to hazards when extended shifts are worked. Workplaces should always aim for best practice, to keep all exposures significantly below the specified standards which will ensure workers are not over-exposed to a hazard.

Manual tasks

The prolonged performance of repetitive tasks without the adequate chance of rest and recovery may result in an occupational overuse injury. The risk of a musculoskeletal injury occurring may also be increased within extended shifts due to the cumulative effects of muscle fatigue, strains and sprains. Workers involved in repetitive manual tasks should have regular breaks.

The Hazardous Manual Tasks Code of Practice 2011 provides guidance on eliminating and controlling risks associated with manual handling.