Shiftwork, and in particular night work, is associated with decreased quantity and quality of sleep. Such changes to sleep manifest themselves in measures such as increased sleepiness, fatigue and accident risk. To manage these risks, particularly in operational environments, a work-related fatigue model has been developed. To date, strong correlations have been observed with a range of measures in empirical and laboratory experiments. This study aimed to determine if the observed relationships between predicted fatigue, alertness and performance also exist in the workplace. Data was analysed from one hundred and ninety three train drivers who filled in sleep and work diaries, wore actigraphs, performed subjective alertness and objective performance tests before and after each shift for a period of two weeks during a normal schedule. Work-related fatigue scores were calculated and compared to alertness and performance measures. The findings of the present study show that there was a stronger relationship between predicted fatigue and self-rated alertness than between fatigue and performance. Furthermore, the fatigue model predicted self-rated alertness better in the afternoon and evening hours, when employees worked up to four consecutive shifts. With further field validation of the current model, there is potential for work-related fatigue to be predicted from actual or potential hours of work. In the future, such models may help clarify the direct and indirect costs of poor fatigue management on safety, productivity, and efficiency. (A)
Abstract