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Extended workdays: effects of 8-hour and 12-hour rotating shift schedules on test performance, subjective alertness, sleep patterns, and psychosocial variables.

Rosa-RR; Colligan-MJ; Lewis-P
Proceedings of the Human Factors Society 30th Annual Meeting, September 29-October 3, 1986, Dayton, Ohio. Santa Monica, CA: Human Factors Society, 1986 Sep; 2:882-884
Around the clock performance and alertness testing and daily quantification of sleep patterns and other personal habits affected by shift work were used to evaluate a schedule based on a 3 to 4 day workweek with 12 hour rotating shifts with respect to the previous schedule based on a 5 to 7 day workweek with three 8 hour rotating shifts. Preliminary analysis of the results recorded after 7 months of adaptation to the new schedule revealed statistically significant effects with respect to type of schedule, length of the shift, circadian rhythm and various interactions. Twelve hour shifts were associated with decreased alertness, less sleep and disruption of individual activities. The longer workday was associated with poorer performance scores which could not be explained by boredom with the task. The new schedule appeared to be associated with a decrease in the degree of alertness of the workers. Sleeping time declined following the switch to the new schedule, but sleep quality in terms of depth of sleep demonstrated potential improvement. During the shorter workweek, the gastrointestinal condition of the workers showed improvement during the night shift and the workers also reported reduced stress. The authors conclude that the switch from the 8 hour to the 12 hour shift schedule results in significant differences regarding a series of cognitive, perceptual motor and motor variables, in addition to subjective sleepiness.
Human-factors-engineering; Ergonomics; Physical-stress; Work-performance; Occupational-health; Repetitive-work; Occupational-diseases; Occupational-exposure; Body-mechanics; Shift-work
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Proceedings of the Human Factors Society 30th Annual Meeting, September 29-October 3, 1986, Dayton, Ohio