The safety and health improvement: enhancing law enforcement departments study: feasibility and findings.

This randomized prospective trial aimed to assess the feasibility and efficacy of a team-based worksite health and safety intervention for law enforcement personnel. Four-hundred and eight subjects were enrolled and half were randomized to meet for weekly, peer-led sessions delivered from a scripted team-based health and safety curriculum. Curriculum addressed: exercise, nutrition, stress, sleep, body weight, injury, and other unhealthy lifestyle behaviors such as smoking and heavy alcohol use. Health and safety questionnaires administered before and after the intervention found significant improvements for increased fruit and vegetable consumption, overall healthy eating, increased sleep quantity and sleep quality, and reduced personal stress.

Efficient driver drowsiness detection at moderate levels of drowsiness.

Previous research on driver drowsiness detection has focused primarily on lane deviation metrics and high levels of fatigue. The present research sought to develop a method for detecting driver drowsiness at more moderate levels of fatigue, well before accident risk is imminent. Eighty-seven different driver drowsiness detection metrics proposed in the literature were evaluated in two simulated shift work studies with high-fidelity simulator driving in a controlled laboratory environment. Twenty-nine participants were subjected to a night shift condition, which resulted in moderate levels of fatigue; 12 participants were in a day shift condition, which served as control. Ten simulated work days in the study design each included four 30-min driving sessions, during which participants drove a standardized scenario of rural highways. Ten straight and uneventful road segments in each driving session were designated to extract the 87 different driving metrics being evaluated. The dimensionality of the overall data set across all participants, all driving sessions and all road segments was reduced with principal component analysis, which revealed that there were two dominant dimensions: measures of steering wheel variability and measures of lateral lane position variability. The latter correlated most with an independent measure of fatigue, namely performance on a psychomotor vigilance test administered prior to each drive. We replicated our findings across eight curved road segments used for validation in each driving session. Furthermore, we showed that lateral lane position variability could be derived from measured changes in steering wheel angle through a transfer function, reflecting how steering wheel movements change vehicle heading in accordance with the forces acting on the vehicle and the road. This is important given that traditional video-based lane tracking technology is prone to data loss when lane markers are missing, when weather conditions are bad, or in darkness. Our research findings indicated that steering wheel variability provides a basis for developing a cost-effective and easy-to-install alternative technology for in-vehicle driver drowsiness detection at moderate levels of fatigue.

The efficacy of a restart break for recycling with optimal performance depends critically on circadian timing.

OBJECTIVES: Under simulated shift-work conditions, we investigated the efficacy of a restart break for maintaining neurobehavioral functioning across consecutive duty cycles, as a function of the circadian timing of the duty periods. DESIGN: As part of a 14-day experiment, subjects underwent two cycles of five simulated daytime or nighttime duty days, separated by a 34-hour restart break. Cognitive functioning and high-fidelity driving simulator performance were tested 4 times per day during the two duty cycles. Lapses on a psychomotor vigilance test (PVT) served as the primary outcome variable. Selected sleep periods were recorded polysomnographically. SETTING: The experiment was conducted under standardized, controlled laboratory conditions with continuous monitoring. PARTICIPANTS: Twenty-seven healthy adults (13 men, 14 women; aged 22-39 years) participated in the study. INTERVENTIONS: Subjects were randomly assigned to a nighttime duty (experimental) condition or a daytime duty (control) condition. The efficacy of the 34-hour restart break for maintaining neurobehavioral functioning from the pre-restart duty cycle to the post-restart duty cycle was compared between these two conditions. RESULTS: Relative to the daytime duty condition, the nighttime duty condition was associated with reduced amounts of sleep, whereas sleep latencies were shortened and slow-wave sleep appeared to be conserved. Neurobehavioral performance measures ranging from lapses of attention on the PVT to calculated fuel consumption on the driving simulators remained optimal across time of day in the daytime duty schedule, but degraded across time of night in the nighttime duty schedule. The 34-hour restart break was efficacious for maintaining PVT performance and other objective neurobehavioral functioning profiles from one duty cycle to the next in the daytime duty condition, but not in the nighttime duty condition. Subjective sleepiness did not reliably track objective neurobehavioral deficits. CONCLUSIONS: The 34-hour restart break was adequate for maintaining performance in the case of optimal circadian placement of sleep and duty periods (control condition) but was inadequate (and perhaps even detrimental) for maintaining performance in a simulated nighttime duty schedule (experimental condition). Current US transportation hours-of-service regulations mandate time off duty but do not consider the circadian aspects of shift scheduling. Reinforcing a recent trend of applying sleep science to inform policymaking for duty and rest times, our findings indicate that restart provisions in hours-of-service regulations could be improved by taking the circadian timing of the duty schedules into account.

Association of perceived stress with sleep duration and sleep quality in police officers.

The objective was to investigate associations ofperceived stress with sleep duration and quality among 430 police officers. Perceived stress was assessed using the perceived stress scale. Sleep duration and quality were assessed using the Pittsburg sleep quality index questionnaire. Mean hours of sleep were determined across quartiles of perceived stress using ANOVA/ANCOVA. Logistic regression was used to obtain odds ratios and 95% confidence intervals for poor sleep quality across perceived stress quartiles. Mean age was 42.1 years. Perceived stress was inversely associated with sleep duration among certain groups: men (p = 0.004), higher-ranked officers (p = 0.002), those with higher depressive symptoms (p 0.097), no military experience (p = 0.006), and higher workload (p = 0.003). Gender, police rank, depressive symptoms, and workload each significantly modified the association between stress and sleep duration. Prevalence of poor sleep quality increased with higher levels of perceived stress; the trend was significant among men only (p < 0.0001), and gender significantly modified this association (interaction p = 0.015). Compared to those in the first quartile of perceived stress, women in the fourth quartile were almost four times and men almost six times more likely to have poor sleep quality. Perceived stress was inversely associated with sleep duration and positively associated with poor sleep quality.

Atypical work hours and metabolic syndrome among police officers.

This study examined whether atypical work hours are associated with metabolic syndrome among a random sample of 98 police officers. Shift work and overtime data from daily payroll records and reported sleep duration were obtained. Metabolic syndrome was defined as elevated waist circumference and triglycerides, low HDL cholesterol, hypertension, and glucose intolerance. Multivariate analysis of variance and analysis of covariance models were used for analyses. Officers working midnight shifts were on average younger and had a slightly higher mean number of metabolic syndrome components. Stratification on sleep duration and overtime revealed significant associations between midnight shifts and the mean number of metabolic syndrome components among officers with less sleep (p = .013) and more overtime (p = .007). Results suggest shorter sleep duration and more overtime combined with midnight shift work may be important contributors to the metabolic syndrome.