Shiftwork and performance.
The twenty-four hour workday: proceedings of a symposium on variations in work-sleep schedules. Johnson LC, Texas DI, Colquhoun WP, Colligan MJ, eds. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 81-127, 1981 Jul; :347-373
The effect of changes in the nature of shiftworkers' jobs on productivity and safety was reviewed. Examination of switchboard operators' response time, error frequencies in meter reading, nodding off by drivers, joining threads by spinners, missing of warning signals, and minor accidents in hospitals showed impaired efficiency on night shifts. Perceptual motor performance showed parallelism between circadian rhythm (CR) and temperature and performance efficiency. Laboratory studies of CRs in performance showed no single CR in performance efficiency. The CR phase in performance appeared to depend on information processing demands of the task under consideration. While these studies predicted that night shift performance (NSP) of memory loaded cognitive tasks might be relatively good, online NSP studies showed consistently poor performance. In a study of memory of 50 nurses, the group showing poor adjustment had higher immediate memory scores at 0400 and 2030 hours, but the reverse was true for those with good adjustment. Poor night shift performance on perceptual motor tasks was due to lack of adjustment of performance rhythms, but performance on more cognitive tasks appeared to be due to adjustment. Therefore performance on cognitive tasks appeared to be relatively good at night provided rhythms were unadjusted. Adjustment levels of CRs to night work depended on shift system and individual differences. The studies indicated that permanent night work resulted in a continuous state of flux in shiftworkers' CRs. Rapidly rotating shift systems resulted in very little disruption and adjustment of rhythms. The author concludes that the studies show there is no single optimal shift system for insuring adequate levels of productivity and safety.
Shift-work; Task-performance; Work-performance; Psychological-factors; Psychophysiology; Mental-fatigue; Circadian-rhythms; Health-protection
Johnson-LC; Texas-DI; Colquhoun-WP; Colligan-MJ
DHHS (NIOSH) Publication No. 81-127
The twenty-four hour workday: proceedings of a symposium on variations in work-sleep schedules