Fatigue is a common factor in workplace accidents and near misses, and although more and more organizations are recognizing the importance of monitoring it, fatigue may often be thought of as synonymous with sleepiness or drowsiness and that all fatigue results from insufficient restorative sleep. Feeling sleepy is certainly a symptom of fatigue, and extended wakefulness is certainly a cause. But fatigue can also result from other causes not related to a lack of sleep, like the nature of the work as well as ergonomic and environmental factors like temperature and noise.
For example, assembly line workers may work typical eight-hour days—shifts not long enough to necessarily contribute to fatigue on their own—but the work area is hot, and a large industrial fan runs constantly throughout the day, filling the environment with a loud droning whir. The workers repeat their tasks on the assembly line hundreds of times in a shift, and this repetition, the drone of the fan, and the ambient heat can lull workers into a tired, non-alert state. Plus, they may still be in this state for their commute home. Similarly, seasonal changes and cold weather often mean that outdoor operations, like construction and resource extraction sites, have to adapt both equipment and employees to the cold. Extended exposure to the cold can have a significant impact on alertness levels. Plus, working in the cold requires proper protection, like large coats, hats, gloves, and boots.
Wearing additional and atypical gear can make everyday tasks more challenging, slow physical reaction time, restrict peripheral vision, and contribute to physical fatigue due in part to the gear's added weight. OSHA defines fitness-for-work as being physically, emotionally, and mentally able to perform essential job functions, and fatigue diminishes fitness-for-work exponentially as it advances, increasing risk to safety and productivity. Because fatigue is a common issue and can manifest a number of ways, it is important that organizations find ways to mitigate the work environment's impact on workers' fatigue levels. This not only influences worker safety directly, it has a positive impact on productivity and performance since a fatigued worker is not performing optimally.