engleski

Performance efficiency and mood on a slow-rotating experimental shift work

The information technologies have redesigned the content of work and created the need for all kinds of services that are available 24 hours a day. Consequently, the cognitive demands of the shift workers’ jobs also changed. The purpose of this study was to gain more information about variations in efficiency on various cognitive and psychomotor tasks performed during three shifts over a 24-hour period. In addition to measuring efficiency, measurements of mood, and some physiological variables were taken. Eighteen well-trained students (9 females, 9 males), without previous shift work experience, took part in the study. Their age ranged from 19 to 30 years. Experimental shift work lasted three weeks. There were three 8-hour shifts each working day covering the whole 24-hour period. Each shift lasted five days and was followed by two days off. A working spell had three work periods (two and a half-hours each), separated by two pauses. At the beginning and the end of each working day the subjects assessed their mood by an adjective check list. Each work period included subjective ratings of alertness, fatigue and readiness for work, measurement of oral temperature and heart rate, performance of letter cancellation tasks (1, 3 and 5 letters), card-sorting tasks (4 and 9 categories), adding tasks (2, 4, and 6 three-digit numbers), simple and four-choice reaction time tasks and measurement of grip strength. All dependent variables showed similar variations over a 24-hour period. The majority of variations were statistically significant with the exception of grip strength and some more complex tasks (choice reaction time, three- and five-letter cancellation tasks). On all tasks the subjects performed best during the afternoon shift. The mood ratings on various scales of the adjective check list were lowest during the night shift. However, only feelings of fatigue and activity showed significant 24-hour variations. The trends of performance efficiency and the physiological and psychological indices of the subjects’ capacity and well being over 24 hours indicated that the afternoon shift was the most efficient in the shift system. Our findings suggest that the cognitive complexity of the shift workers’ jobs could be related to circadian variations in performance efficiency.

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