Working Hours, Sleep, & Fatigue Forum

Abstract for Mining Sector

The Human Factors of Mineworker Fatigue: Unique Properties of Fatigue in the Mining Environment (Extended version)

Max J Martell, BS, NIOSH PMRD
Timothy J. Bauerle, Ph.D., NIOSH SMRD
Dana R. Willmer, Ph.D., NIOSH PMRD
John J. Sammarco, Ph.D., NIOSH PMRD

CORRESPONDING AUTHOR: John J. Sammarco, Ph.D., NIOSH PMRD, 626 Cochrans Mill Rd., Pittsburgh, PA 15236,

Key Messages

  1. Measuring and mitigating mineworker fatigue presents unique challenges compared to other industries.
  2. A multilevel systems approach based on research and implementation completed in other industries may help address mineworker fatigue.
  3. Implementing a lighting-based fatigue intervention for underground miners may be necessary as well, yet remains challenging due to a complex environment, utter darkness, and shiftwork schedules.


Fatigue in the mining industry is a common occurrence, due in part to a combination of multiple fatigue-inducing factors that are present simultaneously. These factors can include shiftwork, long hours, repetitive tasks, physically and mentally demanding jobs, long commute times, sleep deficiency, and poor lighting—any one of which may lead to fatigue on their own. This combination of fatigue components differentiates mining from other industries, and puts mineworkers at a higher risk for fatigue and its consequences. Furthermore, a significant portion of miners work in underground mines, where they spend most of the working day in nearly total darkness. The bodies’ circadian rhythms are highly dependent on the 24-hour cycle of light and dark, so the lack of light in underground mines can disrupt these rhythms and have severe consequences on safety and health.


Fatigue is prevalent across many industries and can have dire consequences, and mining is no exception. An analysis of mining fatalities from 2005 to 2014 indicates that fatigue was the direct cause of 14 deaths, though this does not include those fatalities for which fatigue may have been a contributing factor. As of 2015, there were 317,369 workers in the mining industry, and in some sectors up to 70% of mines implement a shiftwork schedule, with approximately 30% having rotating shifts. Shiftwork schedules—especially rotating shifts—are a known source of fatigue in other industries, and have been shown to contribute to significant increases in rates of accidents and injuries. Shiftwork is often associated with sleep deprivation, another substantial source of worker fatigue. The Centers for Disease Control and Prevention (CDC) has labeled sleep deprivation a public health crisis with approximately one third of adults not getting the necessary amount of sleep per night. Long work hours can also contribute towards sleep deprivation and fatigue, and mining has among the longest with miners on average working 45.8 hours per week, though in some mines it is considerably higher. Time of day is another indicator of fatigue-related incidents, with the highest rates occurring in the third shift and peaking around midnight.

There are approximately 70,000 miners working in underground mines, where they experience very low light levels throughout their working day. The disruption to circadian rhythms from insufficient light during the day is a major contributor to fatigue that puts these mineworkers at an inherently increased risk. Working in dim light has additional consequences by considerably decreasing cognitive functions, such as alertness and reaction time, which can lead to greater chances for mistakes. Consequently, underground miners account for the majority of mining fatalities, though they make up only 20% of the mining workforce.


Unfortunately, there have been limited studies assessing the state of fatigue in the mining industry, which are now outdated. Given the commonly occurring combination of shiftwork, long hours, sleep deprivation, and poor lighting, there is a significant need for further studying the prevalence and negative effects of worker fatigue in the mining industry, particularly in contexts where one or more of these factors may be present. Each of these factors, and the insufficient light in underground mines described before, are likely indicators of the potential for fatigue. Studies thus far have often focused on these factors only in isolation, warranting a human-systems integration approach to fully investigate their combined effects on mineworkers.

Human-systems integration approaches that incorporates technology interventions may further broaden the impact for the mining industry. Lighting, for example, has been successfully implemented as an intervention to address shiftwork-related fatigue in other industries, such as healthcare and aviation, but it has not yet been adapted to the challenging and diverse underground mine environment. There are also very few other industries like underground mining, where workers spend almost the entirety of the working day in near total darkness, and the workers have to constantly adapt to a changing working environment. These issues make lighting an extremely challenging, albeit necessary, intervention to implement in a mine.

The true burden of fatigue in the mining industry is not fully understood. In order to address the severity of this complex issue, there needs to be further research and surveillance conducted throughout the industry to assess and understand the risk, and to study the intersection of people, tasks, equipment, and environment in relation to fatigue.


In the period from 2005 to 2014 there were 517 fatalities in mining. Though not all of these may be attributable solely to fatigue or related causes, it is certain that fatigue is an issue that the industry needs to address. There will be lasting impact in measuring and assessing the true burden of fatigue on mineworkers, as there are no current assessments of the situation in the industry. Approaching fatigue with the organizational and technology components of a human-systems interaction solution may provide significant value for mining as it has done for other industries.

An intervention in the form of a top-down approach like a fatigue management system may be necessary as well to account for both the causes and outcomes of fatigue, as this is a fundamental step in the prevention and treatment of systemic fatigue. Such a system, once implemented, would allow for the simplified identification of fatigue, and for mitigation to take place at a management level, potentially reducing the rates of fatigue-related accidents and fatalities.

Lastly, the application of a lighting intervention in underground mines is a necessary approach to a difficult problem. Implementation of a lighting intervention is the only way to address the lack of light during the workday and to potentially increase alertness and correct disruption to circadian rhythms, which are critical for preventing fatigue. Such an intervention would have widespread applicability to underground mines, and could be adapted for use in other sectors where inadequate light is of a major concern.

Page last reviewed: May 22, 2019