Acute Sleep Deprivation and Circadian Misalignment Associated with Transition onto the First Night of Work Impairs Visual Selective Attention

Background: Overnight 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 Findings: To 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/Significance: These 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

Health care work

Health care work involves high cognitive demands and requires high alertness and concentration levels for a correct assessment and decision making. Sleepiness, sleep deprivation, and vigilance fluctuations, connected to irregular and prolonged working hours, are key factors in conditioning human error, hence accidents and injuries related to both workers and patients. Several studies reported that both physicians and nurses, working on shift and night work and for prolonged duty periods, show significant negative effects on cognitive behavior and psychomotor performance with increased risk of clinical errors such as to hinder patients' safety and health. In order to prevent such adverse consequences and improve workers' well-being and performance efficiency, company management has the hard task of optimizing work organization by acting on working time, available staff and working procedures. In recent years, many attempts have been made by medical associations, governmental institutions, and international directives to set limits to weekly working hours, overtime, length of duty periods, and rest periods of health care personnel, as well as to adopt appropriate compensative measures able to counteract sleep deprivation and sleepiness, in particular as concerns sleep hygiene, napping, use of bright light and medicament