API TR 755-1-2010 pdf download.Technical Support Document for ANSI/API RP 755, Fatigue Risk Management Systems for Personnel in the Refining and Petrochemical Industries.
Fatigue has been also been identified by the U.S. Department of Transportation as the number one safety problem in transportation operations. The number of fatigue-related traffic accidents is considerably higher at night than during daytime.  In fact, a study found that drivers are 50 times more likely to fall asleep at 2 am than at 10 am.  Some studies estimate that the costs of fatigue in US transportation operations exceed $12 billion a year.  Most of these costs stem from the sleep deprivation and fatigue that occurs when work intrudes into normal nocturnal sleeping hours, although in some cases fatigue may be exacerbated by underlying sleep disorders. Fatigue in safety-critical employees impairs their judgment and cognitive reasoning. Divided attention tasks requiring anticipation and proactive planning are typically the first to degrade. As fatigue impairment progresses, the likelihood of automatic behavior (performance of tasks without cognitive awareness) and “microsleep” lapses of attention significantly increases. The risk of such occurrences is proportionate to the degree of vigilance required to safely perform a task. Fatigue also affects mood.  The National Sleep Foundation  found that people who do not get enough sleep are more likely get impatient or aggravated and have difficulty getting along with others. Increased irritability and stress negatively influences personal, work, and family relationships, resulting in inadequate/ineffective communications.
Fatigue also has been associated with an increase in Lost Productive Time (LPT).  Among workers reporting fatigue, 65.7% reported health-related LPT compared to 26.4% of those without fatigue. Workers with fatigue cost employers $136.4 billion annually in health-related LPT, an excess of $101.1 billion compared to workers without fatigue. Fatigue impaired work ability primarily by increasing workers’ time to accomplish tasks and impairing their concentration. In addition, fatigued workers reported more physical health and social functioning problems than workers without fatigue. Fatigue also correlates with increased absenteeism (Figure 2) and turnover as well as reduced morale and poorer labor relations. Industrial surveys reveal that absenteeism rates are nearly double in facilities that have severe fatigue problems among their employees, as compared to facilities in which fatigue is not a problem.  No matter how well-trained, skilled, motivated, or experienced they are, fatigued operators tend to behave more erratically and unpredictably. Unfortunately, many of these incidents are incorrectly blamed on behavioral problems rather than on physiology. Thus understanding human physiology is the key to successfully identifying and managing the inherent problems of shiftwork and fatigue-related human error. The consequences of fatigue also impact a company’s operating efficiency and costs. Fatigue results in reduced productivity and customer service quality, reduced operating reliability and decreased operating profit, increased health and wellness costs, and higher overall costs, risks, and liabilities. There is considerable investigative evidence that fatigue has contributed to serious incidents and accidents in industrial operations, nuclear power plants, and in all modes of transportation.
It seems intuitive that fatigue risk could be controlled simply by limiting the number of hours of work and protecting the daily and weekly minimum hours of rest. This “Hours of Service” approach evolved in the early 1900s as the practice of operating at night with extended hours and 24/7 work schedules spread across multiple industries following the commercialization of electric light. The emerging labor movement in the early 1900s eventually provided the impetus to implement Hours of Service (HoS) regulations. As a result, the issue of workplace fatigue became intertwined with labor pay and rights issues and led to regulatory limits on work/duty duration and minimums of off-duty time duration in all transportation modes by the middle of the 20th century, and eventually some other industries such as nuclear power. In Europe, influential research on both the risk of accidents and the sociological and medical impacts of shiftwork accelerated the momentum. The EU Working Time Directives have now placed limits on work and rest hours in most industries and occupations. However, advances in the science of sleep, circadian rhythms and workplace fatigue over the past 30 years have shown that relying simply on a prescriptive Hours of Service approach is insufficient.