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The effects of consecutive night shifts and shift length on cognitive performance and sleepiness: a field study
Rashid Haidarimoghadam1, Reza Kazemi1, Majid Motamedzadeh1
1a Ergonomics Department , Hamedan University of Medical Sciences , Iran.
Introduction:
The aim of this study was to evaluate the effects of consecutive night shifts (CNS) and shift length on cognitive performance and sleepiness.
Materials And Methods:
This study evaluated the sleepiness and performance of 30 control room operators (CROs) working in 7 nights, 7 days, 7 days off (7N7D7O) and 30 CROs working in 4 nights, 7 days, 3 nights, 7 days off (4N7D3N7O) shift patterns in a petrochemical complex on the last night shift before swinging into the day shift. To assess cognitive performance, the n-back test, continuous performance test and simple reaction time test were employed. To assess sleepiness, the Karolinska sleepiness scale was used.
Results:
Both schedules indicated that the correct responses and response times of working memory were reduced (p = 0.001), while intentional errors and sleepiness increased during the shift work (p = 0.001). CNS had a significant impact on reaction time and commission errors (p = 0.001).
Conclusion:
The main duty of CROs at a petrochemical plant is checking hazardous processes which require appropriate alertness and cognitive performance. As a result, planning for appropriate working hours and suitable number of CNS in a rotating shift system is a contribution to improving CRO performance and enhancing safety.
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