Iran Occupational Health

Background and aims: Shift work and in particular night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue; it is also one of the major contributors of increasing the likelihood of risk of accidents in the industry. Better matching between individuals’ circadian rhythm and night shift and higher work performance can be achieved via designing an appropriate work shift pattern. The aim of this study was to compare the effect of two different rotating night shifts on information processing and alertness.
Methods: This cross-sectional study conducted among 60 employees of the petrochemical industry control rooms with two different shift pattern consists of 7 consecutive nights (or 7 N) and 4 nights (4N). To assess the cognitive performance, n-back test, continuous performance test and simple reaction time test were employed. For assessing alertness the Karolinska Sleepiness Scale (KSS) were used.
Results: Results from the both schedules indicated that the accuracy and speed of working memory and reaction time were significantly reduced (p<0.001), while attentional errors and sleepiness increased (p<0.01) during the shift work. Consecutive night shifts had a significant impact on reaction time and commission errors (p>0.05).
Conclusion: The main duty of control room operators (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 consecutive night shifts in a rotating shift system is a contribution to improving CROs performance and alertness and enhancing the safety.