• What law applies
• About fatigue
• Effects of shift work and extended hours
• Effects of fatigue
  • Work performance
  • Micro sleeps
  • Health effects of fatigue
• Managing fatigue
  • Responsibility for managing fatigue
  • Risk management
  • Factors to consider when managing fatigue

• Risk management

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Factors to consider when managing fatigue

The following factors should be considered when managing fatigue:

• Roster design;
• Commuting;
• Shift rotation;
• Sleep inertia;
• Breaks;
• Occupational exposure levels; and
• Manual tasks.

Roster design

When determining if roster design is contributing to fatigue, consider the following:

• 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;
• Length of shifts worked - this can contribute to fatigue;
• Previous hours and days worked - the effects of fatigue are cumulative, workers may have sleep debt due to the length of previous shifts;
• Type of work being performed - pay particular attention to the level of physical and/or mental effort required; and
• Time of the day when the work is being performed - remember that disrupting the body's circadian rhythms can cause fatigue and affect performance.

The key to managing fatigue successfully is ensuring that workers are given sufficient time between shifts. Adults require approximately seven to eight continuous hours of daily sleep. One way of doing this would be giving workers two successive full days off within a seven day period, so workers can catch up on their night sleep.

Commuting

Excessive hours spent travelling to and from work can extend the effective length of a shift, reduce the time available for sleep and recovery between shifts, and may have significant effects on fatigue levels. When combined with work-related fatigue, driving to and from work can be hazardous.

Shift rotation

If the starting times of shifts vary, the cycle should begin with an early start and move progressively later. Where a rotating three shift system is in operation the preferred rotation is day, afternoon, and night. This will allow workers the maximum opportunity for rest between shifts.

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.

Sleep inertia 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; and
• 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.

Consider the following when deciding on the length and frequency of breaks within a shift:

• Type of work being performed ¿ the greater the physical and/or mental effort required, the longer the total break time required per shift; and
• Length of shifts worked¿ the longer the shift the longer the total break time required per shift.

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 Manual Tasks Code of Practice 2010 provides guidance on eliminating and controlling risks associated with manual handling.