Abstract
BackgroundOvernight operations pose a challenge because our circadian biology promotes sleepiness and dissipates wakefulness at night. Since the circadian effect on cognitive functions magnifies with increasing sleep pressure, cognitive deficits associated with night work are likely to be most acute with extended wakefulness, such as during the transition from a day shift to night shift.Methodology/Principal FindingsTo test this hypothesis we measured selective attention (with visual search), vigilance (with Psychomotor Vigilance Task [PVT]) and alertness (with a visual analog scale) in a shift work simulation protocol, which included four day shifts followed by three night shifts. There was a nocturnal decline in cognitive processes, some of which were most pronounced on the first night shift. The nighttime decrease in visual search sensitivity was most pronounced on the first night compared with subsequent nights (p = .04), and this was accompanied by a trend towards selective attention becoming ‘fast and sloppy’. The nighttime increase in attentional lapses on the PVT was significantly greater on the first night compared to subsequent nights (p<.05) indicating an impaired ability to sustain focus. The nighttime decrease in subjective alertness was also greatest on the first night compared with subsequent nights (p<.05).Conclusions/SignificanceThese nocturnal deficits in attention and alertness offer some insight into why occupational errors, accidents, and injuries are pronounced during night work compared to day work. Examination of the nighttime vulnerabilities underlying the deployment of attention can be informative for the design of optimal work schedules and the implementation of effective countermeasures for performance deficits during night work.
Highlights
The ubiquitous ‘night shift’ of modern 24-hour society is a challenge to our biological propensity for daytime wakefulness and nighttime sleep
Because there was no effect of sleep schedules on our cognitive measures we pooled the data from both sleep schedule groups for the analyses reported here
These nocturnal deficits provide some insight into why occupational errors, accidents and injuries are highly prevalent in overnight operations
Summary
The ubiquitous ‘night shift’ of modern 24-hour society is a challenge to our biological propensity for daytime wakefulness and nighttime sleep. Operational needs sometimes require workers to be scheduled for a ‘quick comeback’ where they work the day followed by a night shift with only an 8 hour break in between, leaving little opportunity for sleep. In such circumstances, workers could be awake for 24 consecutive hours by the end of the first night shift [6], a duration of wakefulness associated with increased risk of errors, accidents and injuries [5] comparable to those associated with alcohol intoxication [9] [10,11,12]. Examination of the nighttime vulnerabilities underlying the deployment of attention can be informative for the design of optimal work schedules and the implementation of effective countermeasures for performance deficits during night work
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have