These documents contain references to the effects of fatigue as part of a larger study or report.

Work Schedules
Description
Work related fatigue can become a problem when mining personnel work longer shifts and more consecutive days during the work week. According to the U.S. Bureau of Labor Statistics, American workers log more hours a year (1,966 hours) than those in any other industrialized country. Many workers work overtime on a regular basis.

The Aging Workforce: An Emerging Issue in the Mining Industry
Description
According to the Bureau of Labour Statistics (BLS), workforce estimates of median age suggest that the median age of the mining workforce, which has been experiencing overall declines in numbers of employees, is rising more rapidly than for the overall U.S. civilian labor force.