Breaking Up Sitting with Light-Intensity Physical Activity: Implications for Shift-Workers

Calibrated to drive: Measuring self-assessed driving ability and perceived workload after prolonged sitting and sleep restriction

Self-assessed driving ability may differ from actual driving performance, leading to poor calibration (i.e., differences between self-assessed driving ability and actual performance), increased risk of accidents and unsafe driving behaviour. Factors such as sleep restriction and sedentary behaviour can impact driver workload, which influences driver calibration. This study aims to investigate how sleep restriction and prolonged sitting impact driver workload and driver calibration to identify strategies that can lead to safer and better calibrated drivers. Participants (n = 84, mean age = 23.5 ± 4.8, 49 % female) undertook a 7-day laboratory study and were randomly allocated to a condition: sitting 9-h sleep opportunity (Sit9), breaking up sitting 9-h sleep opportunity (Break9), sitting 5-h sleep opportunity (Sit5) and breaking up sitting 5-h sleep opportunity (Break5). Break9 and Break5 conditions completed 3-min of light-intensity walking on a treadmill every 30 min between 09:00-17:00 h, while participants in Sit9 and Sit5 conditions remained seated. Each participant completed a 20-min simulated commute in the morning and afternoon each day and completed subjective assessments of driving ability and perceived workload before and after each commute. Objective driving performance was assessed using a driving simulator measuring speed and lane performance metrics. Driver calibration was analysed using a single component and 3-component Brier Score. Correlational matrices were conducted as an exploratory analysis to understand the strength and direction of the relationship between subjective and objective driving outcomes. Analyses revealed participants in Sit9 and Break9 were significantly better calibrated for lane variability, lane position and safe zone-lane parameters at both time points (p < 0.0001) compared to Sit5 and Break5. Break5 participants were better calibrated for safe zone-speed and combined safe zone parameters (p < 0.0001) and speed variability at both time points (p = 0.005) compared to all other conditions. Analyses revealed lower perceived workload scores at both time points for Sit9 and Break9 participants compared to Sit5 and Break5 (p = <0.001). Breaking up sitting during the day may reduce calibration errors compared to sitting during the day for speed keeping parameters. Future studies should investigate if different physical activity frequency and intensity can reduce calibration errors, and better align a driver's self-assessment with their actual performance.

Does knowledge of sleep hygiene recommendations match behaviour in Australian shift workers? A cross-sectional study

OBJECTIVES

Shiftworkers routinely obtain inadequate sleep, which has major health consequences. Sleep hygiene describes a range of behaviours, lifestyle and environmental factors that can improve sleep. To date, limited research has examined sleep hygiene in shiftworkers. This study aimed to assess the sociodemographic and behavioural correlates of sleep hygiene knowledge and engagement with sleep hygiene practices in Australian shiftworkers.

STUDY DESIGN

An online, cross-sectional survey.

SETTING AND PARTICIPANTS

Australian adults from across multiple industries (n=588) who work shift work.

MEASURES

The online survey included questions regarding sleep hygiene knowledge and questions from modified versions of the Pittsburgh Sleep Quality Index and Sleep Hygiene Index.

RESULTS

Of the 588 participants, 52.9% reported having heard of 'sleep hygiene'. Of these participants, 77.5% reported understanding the term moderately, extremely or very well. Engagement with each sleep hygiene practice was varied. Common sleep hygiene practices were controlling the bedroom environment (eg, a cool, dark and quiet bedroom). Less common practices were avoiding light as bedtime approaches. Logistic regressions revealed that shiftworkers who had heard of sleep hygiene were more likely to engage in sleep hygiene practices and had better sleep quality compared with those who had not heard of sleep hygiene. Increased engagement in sleep hygiene practices did not predict the likelihood of individuals reporting better sleep quality.

CONCLUSIONS

Shiftworkers demonstrated varied knowledge, understanding and engagement with individual sleep hygiene practices. Future research should focus on the development of sleep hygiene interventions that accommodate the unique challenges of shift work to optimise sleep.

Monitoring calf circumference: changes during prolonged constrained sitting

Prolonged sitting has been associated with negative health effects; however, short-term time-varying exposure and response data is lacking. Twenty-two young and healthy participants were seated for 2 hours with the instruction to avoid the confounding effects of large leg movements while calf circumference, perceived discomfort, and lower limb muscle activity were collected. Calf circumference increased significantly (0.90 ± 0.32 cm) during sitting with no statistical differences between sexes. Perceived discomfort increased significantly over time in the low back and gluteal regions (p = 0.001-0.072, η_p²=0.080-0.360). On average, it took 20.31 ± 10.87 minutes of walking for calf measures to return to pre-sitting baseline. These results suggest that sitting for 2 hours without activity breaks may not be advisable and that recovery may take longer than expected. The exposure/response data from this study may be helpful in the design of future studies, with a larger and more general population, aiming to better define recommended duration/activity ratios for sitting-focused occupations. Practitioner summary: Leg swelling is a concern in prolonged sitting. In this study of young, healthy participants, we found a 2 hour constrained sitting exposure (controlling for large leg movements) induced significant increases in calf circumference that took an average of 20.31 ± 10.87 min of walking to return to baseline.Abbreviations: FMD: flow-mediated dilation, GSC: gastrocnemius; TA: tibialis anterior; EMG: electromyography; VAS: visual analog scale; MVC: maximum voluntary contractions.

Physical activity and sedentary behaviour in shift and non-shift workers: A systematic review and meta-analysis

Research examining the prevalence, physical activity (PA) and sedentary behaviour (SB) in shift workers show mixed results. This systematic review and meta-analysis aimed to compare PA and SB in shift workers with non-shift workers following the PRISMA guidelines. Ebscohost megafile ultimate (CINHAL, E-journals, Academic search ultimate, health source consumer edition, SPORT Discus), PubMed, Scopus, Web of Science, and Science Direct databases were searched up to April 2021. Cross-sectional and baseline data from longitudinal studies reporting PA and SB in full time workers were eligible. Data on participants characteristics and time spent in PA and SB and/or prevalence of workers meeting PA guidelines were extracted and pooled with random effects model. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) 10-item checklist was adapted and used. A total of 49 studies met inclusion criteria and 21 studies included for meta-analysis. The prevalence of meeting physical activity guidelines (OR 0.84, 95% CI: 0.68, 1.03) and standardized mean difference (SMD) of time spent in moderate-to-vigorous physical activity (SMD -0.1, 95% CI: -0.4, 0.20) were similar in shift and non-shift workers. Time spent in sedentary behaviour was lower in shift workers than non-shift workers (SMD -0.2, 95% CI: 0.50, -0.001). While the differences in PA are not so evident between shift and non-shift workers, the prevalence of sufficient PA was low in both groups. These preliminary findings provide support for inclusion of physical activity and sedentary behaviour in health promotion interventions targeted at shift workers.