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Worker fatigue is one of the most common contributing factors to workplace accidents and near-misses. Fatigue can manifest from a number of reasons, both work-related and not. Most fatigue and its symptoms accompany sleep debt, an accumulation of insufficient restorative sleep, but it can also arise from mental or physical exertion, personal health factors, and psychosocial factors. Regardless of its cause, fatigue is more than just being tired, and it can impair mentally as well as physically.

Disrupted and irregular Sleep Habits

Shift workers, especially those who work rotating shifts, are especially susceptible to fatigue due to the disruption of their circadian rhythm, or sleep/wake cycle. The human biological system operates on an internal clock in which different functions run on different cycle lengths. The circadian rhythm lasts approximately 24 hours, with various functions rising or falling at various times throughout. These rising and falling functions—heart rate, body temperature, and others—create a powerful physiological tendency to sleep at night and be awake during the day. Difficulties occur when work-time arrangements cause individuals to work against this tendency, which affects both the ability to remain alert and the ability to sleep.

Employees who work rotating shift schedules, in which they alternate between day and night shifts, are especially susceptible to sleep debt and associated fatigue symptoms because it takes time for a person to become better adjusted to a new schedule. In fact, at the beginning of every new shift cycle, workers are much more likely to experience what is commonly called “jet lag,” because they are working against two things: their natural circadian rhythms, which expect them to be awake during the day and asleep at night, and having become adjusted to their previous shift cycle, must now readjust.

High levels of fatigue cause reduced performance and productivity in the workplace and increase the risk of accidents and injuries. Fatigue affects the ability to think clearly, which is vital when making safety-related decisions and judgments. People who are fatigued are unable to gauge their own level of impairment. As a result, fatigued people are unaware that they are not functioning as well or as safe as if they were not fatigued. Unfortunately, it is not until the point of failure where fatigue has caused or contributed to an incident or a near miss that we tend to focus on solutions, controls, or other ways to manage fatigue risk.

Mitigating the Risk of Fatigue

When safety managers and business owners turn their attention to fatigue, they soon see that it is a three-fold challenge: First, there is no objective, standard definition of fatigue until the point of failure. Second, fatigue is a non-static variable, making it difficult to measure. And third, a majority of behaviors impacting fatigue are not work-related and occur outside of the workplace, limiting the ability for them to be controlled by workplace policies or safety measures. But Predictive Safety’s PRISM Fatigue Management System is able to meet this challenge.

In essence, the PRISM fatigue management system works by calculating fatigue risk according to several inputs. Some inputs are based on the data points in a Fatigue Risk Index, which includes things like shift times and lengths against typical circadian rhythms. Other inputs come from employees, like telling the system at clock-in how much sleep they had, and through taking brief alertness tests. The output generated by PRISM’s predictive algorithm allows for more informed shift scheduling and allows supervisors and employees monitor their alertness and apply countermeasures as appropriate to reduce or avoid fatigue. In the case that PRISM identifies a significant risk or a potentially impaired employee, it triggers a notification to the designated supervisor.

A study of PRISM at a large iron mine showed that monitoring and managing fatigue risk had an immediate impact on mine employees’ hours worked during high-risk fatigue zones. Consequently, over the course of the next year, shift attendance improved about 3% and incident rates per produced metric ton dropped about 35%. When asked about their experience using PRISM, 84% of workers and supervisors agreed that fatigue risk monitoring increased their awareness of job safety and performance. In addition, 80% of workers and supervisors agreed that fatigue risk management increased their ability to manage their own fatigue levels at work. Plus, 94% of workers thought that monitoring fatigue risk would help managers and supervisors understand the workforce better and help to improve their working conditions, and 96% of workers reported feeling better about their work environment knowing that their co-workers were being monitored for alertness and fatigue.

The Science of Fatigue

Fatigue is both a personal and occupational risk factor. It is a complex mental state characterized by a lack of alertness and reduced mental and physical performance often accompanied by drowsiness. It is associated with spending long hours awake, an inadequate amount of sleep over an extended period or an insufficient quality of sleep, high physical and mental loads, and a number of non-work-related factors. From a practical viewpoint, it is doubtful that fatigue in the workplace can be eliminated altogether, but it certainly can be controlled and limited by proper management. Fatigue management is a shared responsibility between the organization and all its employees, and all stakeholders should participate in order to provide the safest and healthiest working environment possible.


References and Further Reading

Schutte, P.C. (2009). Fatigue risk management: Charting a path to a safer workplace. The Southern African Institute of Mining and Metallurgy, Hard Rock Safe Safety Conference: Sun City, South Africa.

Harrington, J.M. (2001). Health effects of shift work and extended hours of work. Occupational and Environmental Medicine 58(1): 68–72.

Van Dongen, H.P.A. & Dinges, D.F. (2005). Sleep, circadian rhythms, and psychomotor vigilance. Clinics in Sports Medicine 24(2): 237–249. doi:10.1016/j.csm.2004.12.007

Caldwell, J.A., Caldwell, J.L., & Schmidt, R.M. (2008). Alertness management strategies for operational contexts. Sleep Medicine Reviews 12(4): 257–273. doi:10.1016/j.smrv.2008.01.002

Heitmann, A. (2011). Evaluation of fatigue systems. Awake Institute.

Lerman, S.E., et al. (2012). Fatigue risk management in the workplace. Journal of Occupational and Environmental Medicine 54(2): 231–258.

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