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Sleep deprivation and time of day have been shown to play a critical role in decreasing ability to sustain attention, such as when driving long distances. However, a gap in the literature exists regarding external factors, such as workload. One way to examine workload is via modulating time on task. This study investigated the combined effect of sleep deprivation, time of day, and time on task as a workload factor on driving performance. Twenty-one participants (18–34 years, 10 females) underwent 62 h of sleep deprivation within a controlled laboratory environment. Participants received an 8-h baseline and 9.5-h recovery sleep. Every 8 h, participants completed a Psychomotor Vigilance Task (PVT), Karolinska Sleepiness Scale (KSS), 30-min monotonous driving task and NASA-Task Load Index (TLX). Driving variables examined were lane deviation, number of crashes, speed deviation and time outside the safe zone. Workload was measured by comparing two 15-min loops of the driving track. A mixed model ANOVA revealed significant main effects of day and time of day on all driving performance measures (p < .001). There was a significant main effect of workload on lane deviation (p < .05), indicating that a longer time on task resulted in greater lane deviation. A significant main effect of day (p < .001) but not time of day for the NASA-TLX, PVT and KSS was found. Time on task has a significant further impact on driving performance and should be considered alongside sleep deprivation and time of day when implementing strategies for long-distance driving.

The aim of this review was to explore the extent and nature of evidence exploring shiftwork and disruptions to cortisol. A systematic search was conducted across five databases: Medline, EMBASE, Psych INFO, Joanna Briggs Institute and PubMed between July-August 2020. Cortisol data were characterised into three main outcomes, 1) cortisol levels, 2) cortisol rhythm, and 3) cortisol awakening response (CAR) during shiftwork. Main findings demonstrate that shiftwork, especially night shift, significantly disrupts production of cortisol, the cortisol rhythm and CAR and, irregular shift schedules produce greater disruptions to cortisol than regular shift schedules. It was difficult to draw conclusions about the impact of shiftwork on movement of the cortisol rhythm and adaptation or recovery of the cortisol rhythm to and from night shift as the literature lacks consistency in definition of methods and variables. The present state of literature demonstrates cortisol levels, cortisol rhythm and the CAR are all disrupted by shiftwork, but there is a lack of consistency between studies on use of variables and most of the literature focuses on acute disruption rather than chronic effects. It will be important for future studies to investigate possible mechanisms that link shiftwork, disruptions to cortisol and chronic health conditions prevalent in shiftworkers. Refereed/Peer-reviewed

Purpose: Residential support workers (RSW) engage in overnight "sleepover" shifts as well as more traditional "standup" night shifts. While research has investigated the consequences of night and on-call work for sleep in other industries, the sleep of RSW has not been evaluated. Method: In a single-provider case study, six employees completed the Pittsburgh Sleep Quality Index (PSQI), the Depression Anxiety Stress Scale (DASS), a 2-week sleep diary, and a 30 min interview, and four also completed the Shirom-Melamed Burnout Measure (SMBM). Results: Participants reported sleep of poor quality, low-mild DASS scores, and evidence of SMBM scores that were elevated relative to norms. Sleep was significantly lower (p < 0.01) following "standup" shifts (mean = 4.1, SD = 1.8 h) and during "sleepover" shifts (mean = 5.6, SD = 2.0 h) compared to non-shift nights (mean = 7.3, SD = 2.3 h). Interviews suggested that sleep fluctuates with level of patient care, colleague assistance, stress, and the quality of the sleeping environment (including bed comfort, light, noise and perceived safety). Conclusions: Findings suggest that this group have sleep that is insufficient and of poor quality and that they may be at risk of burnout. Consideration of ways to optimise sleeping conditions at work (e.g. through noise or stress reduction) would be beneficial. Research in this area has the potential to facilitate improvements in health and safety in this growing industry.

The human circadian system is controlled by a central master clock in the brain and peripheral clocks in organs such as the liver, heart, pancreas, muscle, and adipose tissues. The main time cue for our central clock is light, while for peripheral clocks, food intake can also be a time cue. When these clocks are synchronized, food-seeking behavior, gastrointestinal activity, and metabolic function are higher during the day and reduced at night whilst people are primed for sleep. Shiftwork changes sleep timing as well as meal and snack timing and content. This can lead to circadian rhythm disruption, changing appetite and energy-regulating hormones as well as impairing metabolic function. This chapter will review mechanisms underpinning adverse metabolic outcomes due to circadian misalignment, and examine evidence from human studies relating to the potential implications of irregular food intake.