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Safeguard OSH Solutions - Thomson Reuters

Safeguard Magazine

Health matters—The fatigue factor

PHILIPPA GANDER reviews recent scientific progress in the understanding of work-related fatigue and how to manage it for improved safety – and health.

The HSE Amendment Act (2002) identified fatigue as a workplace hazard, placing a shared responsibility on employers and employees to manage it.

Fatigue has traditionally been managed by setting limits on maximum work hours and minimum breaks. However the effectiveness of this approach is increasingly being challenged. For example, the USA introduced regulatory limits on work hours for locomotive engineers in 1907, for truck drivers in 1937, and for airline pilots in 1938. Nevertheless, in 2011 “addressing human fatigue” was number two in the National Transportation Safety Board’s list of the ten most-wanted safety improvements across all transport modes.

New fatigue management approaches are being introduced, particularly in 24/7 industries where work intensification and financial pressures are increasing the demands on restricted numbers of skilled staff. These approaches combine advances in sleep science, behavioural science and safety science. They are based on better understanding of the causes of fatigue and its role in human error and accidents, together with improved processes for fatigue hazard identification, risk assessment, and management.

Fatigue is a state of reduced performance capability. It is caused by an imbalance between the exertion of all waking activities (not only work demands) and recovery, which requires adequate sleep on a regular basis.

The most common causes of workplace fatigue are:

  • • 
    not getting enough sleep and/or staying awake longer than about 16 hours;
  • • 
    working at times when the circadian body clock is actively promoting sleep and trying to sleep when it is actively promoting wake; and
  • • 
    workload (mental and/or physical).

In this view, shift work is any work pattern that displaces sleep from its optimal time in the circadian body clock cycle. The body clock is sensitive to light via a dedicated nerve tract coming from each eye (separate from vision). This light sensitivity tends to keep it locked on to the day/night cycle and actively promoting sleep at night, regardless of a person’s work pattern.

Fatigue risk management systems (FRMS) are the most comprehensive of the new approaches. They are data driven and continuously monitor and manage actual fatigue risk using two process loops (above).

In the FRM processes loop, fatigue levels are monitored using a range of measures. When a potential fatigue hazard is identified, a risk assessment is undertaken and additional mitigations are put in place, if needed. The effectiveness of all mitigations is captured by the ongoing monitoring of fatigue levels.

The safety assurance processes monitor the effectiveness of the FRM processes. They periodically evaluate fatigue against fatigue safety performance indicators, monitoring trends that could indicate an emerging fatigue hazard and external changes that could have an impact on fatigue (for example regulatory or organisational changes).

The two process loops are supported by a policy, documentation of fatigue risk management activities, and training for all staff with a role in FRMS (including senior and line managers, schedulers, and front-line staff).

FRMS include multiple strategies, both to reduce fatigue and to mitigate the safety risk posed by fatigued people in a workplace. The safety risk depends on the nature of the job and the other hazards present. For example, the consequences of being unable to stay awake are different for a truck driver on the road alone at night versus an airline pilot who is part of a two-person flight deck crew. The risks for flight safety of having one pilot asleep are different when the aircraft is on automatic pilot in mid-cruise versus during approach and landing, when crew workload and safety risks are greater.

Better understanding of the effects of sleep loss and disrupted body clock cycles has also raised new occupational health questions. Large population-based studies consistently find that people who report typically sleeping less than seven hours per night are more likely to develop obesity, type 2 diabetes and cardiovascular disease. Experiments that restrict the sleep of healthy young people for days to weeks cause physiological changes expected to increase the risk of developing these conditions. At least in the short term, these effects can be reversed by adequate recovery sleep.

In 2007, the UN body responsible for cancer research concluded that shift work that involves circadian disruption is probably carcinogenic to humans. Denmark now compensates breast cancer as an industrial injury for women who have worked at least one night a week for at least 20-30 years, and who have no other significant breast cancer risk factors.

Eating out of step with the circadian body clock cycle can cause significant disruption to the functioning of liver, kidney, pancreas, and gut. Metabolic changes seen at the cellular level may contribute to the development of obesity and type 2 diabetes.

These chronic health conditions have multiple causes and the relative contribution of work-related sleep loss and circadian disruption to them is not yet clear. Nevertheless, minimising these causes of fatigue is likely to become increasingly important not only for workplace safety, but also for maintaining health and wellbeing.

Professor Philippa Gander is director of the Sleep/Wake Research Centre at Massey University’s College of Health.

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