Bryan Vila

Atypical Work Hours and Metabolic Syndrome Among Police Officers

ABSTRACT 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.

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.

Shift-work and suicide ideation among police officers

BACKGROUND This cross-sectional study assessed the association of shift work with suicide ideation among police officers. METHODS Shift work was based on daily payroll records over 5 years (41 women, 70 men). Standardized psychological measures were employed. ANOVA and Poisson regression were used to evaluate associations. RESULTS Among policewomen with increased depressive symptoms, prevalence of suicide ideation increased by 116% for every 10-unit increase in percentage of hours worked on day shift (prevalence ratio (PR) = 2.16; 95% confidence interval (CI) = 1.22-3.71). Among policemen with higher (but not lower) posttraumatic stress disorder (PTSD) symptoms, prevalence of suicide ideation increased by 13% with every 10-unit increase in the percentage of hours worked on afternoon shift (PR = 1.13; 95% CI = 1.00-1.22). CONCLUSION Prevalence of suicide ideation significantly increased among policewomen with higher depressive symptoms and increasing day shift hours, and among policemen with higher PTSD symptoms with increasing afternoon shift hours.

Shift work and the incidence of injury among police officers

BACKGROUND Police officers may be injury prone due to fatigue, erratic work hours, and insufficient sleep. This study explored injury incidence among police officers across shifts. METHODS Day-to-day shift data from computerized payroll records (1994-2010) were available from a mid-sized urban police department (n = 430). Sleep duration, shift activity level, returning to work after days off, and injury incidence over time were also examined. RESULTS Age-adjusted incidence rate ratio (IRR) for injury on the midnight shift was 72% larger than the day shift (IRR = 1.72; 95% CI = 1.26-2.36) and 66% larger than the afternoon shift (IRR = 1.66; 95% CI = 1.23-2.25). Injury incidence for the first day back on the midnight shift was 69% larger than day shift (IRR = 1.69; 95% CI = 1.23-2.32) and 54% larger than the afternoon shift (IRR = 1.54; 95% CI = 1.36-1.76). High activity level combined with midnight shift work put officers at increased injury risk (IRR = 2.31; P = 0.0003). Probability of remaining free of injury was significantly higher for day shift than midnight shift (P < 0.0001). CONCLUSIONS Higher injury risk was associated with night shift work in police officers. Night shift combined with high work activity was strongly associated with injury risk. There was a significantly higher probability of not being injured on day compared to midnight or afternoon shifts.

Shift work and sleep: the Buffalo Police health study

Purpose – Working on the night shift is a potential source of occupational stress and has been associated with sleep disorders. The purpose of this paper is to investigate the association between shift work and sleep problems among police officers from Buffalo, New York.Design/methodology/approach – Randomly selected officers (n=111) responded to questions on sleep quality and quantity. Shift work data were obtained from daily payroll records from 1994 to the exam date (1999‐2000). Prevalence ratios (PR) were obtained using Poisson regression models that examined associations of shift work with sleep quality and quantity.Findings – Among police officers, night shift work was significantly and independently associated with snoring and decreased sleep duration.Originality/value – Although the sleep questions were similar to those used in validated sleep questionnaires, a major strength of this study was the availability of daily work history data on all officers for up to five years prior to the current exa...

A combined field and laboratory design for assessing the impact of night shift work on police officer operational performance.

OBJECTIVES This study assessed the utility of a combined field and laboratory research design for measuring the impact of consecutive night shift work on the sleepiness, vigilance, and driving performance of police patrol officers. DESIGN For police patrol officers working their normal night shift duty cycles, simulated driving performance and psychomotor vigilance were measured in a laboratory on two separate occasions: in the morning after the last of five consecutive 10.7-h night shifts, and at the same time in the morning after three consecutive days off duty. Order of participation in conditions was randomized among subjects. SETTING Subjects experienced manipulation of sleep schedules due to working night shifts in a real operational environment, but performance testing was conducted under controlled laboratory conditions. PARTICIPANTS N = 29 active-duty police patrol officers (27 male, 2 female; age 37.1 ± 6.3 years) working night shift schedules participated in this study. RESULTS Simulated driving performance, psychomotor vigilance, and subjective sleepiness were significantly degraded following 5 consecutive night shifts as compared to 3 consecutive days off duty, indicating that active-duty police officers are susceptible to performance degradation as a consequence of working nights. CONCLUSIONS This combined field and laboratory research design succeeded in bridging the gap between the realism of the operational environment and the control of laboratory performance testing, demonstrating that this is a useful approach for addressing the relationship between shift work induced fatigue and critical operational task performance.

Police drowsy driving: predicting fatigue-related performance decay

Purpose – Fatigue associated with shift work is a well-established and pervasive problem in policing that affects officer performance, safety, and health. It is critical to understand the extent to which fatigue degrades officer driving performance. Drowsy driving among post-shift workers is a well-established risk factor yet no data are available about officer injuries and deaths due to drowsy driving. The purpose of this paper is to assess the impact of fatigue associated with work shift and prior sleep on officers’ non-operational driving using laboratory experiments to assess post-shift drowsy driving risks and the ability of a well-validated vigilance and reaction-time task to assess these risks. Design/methodology/approach – Experienced police patrol officer volunteers (n=78) from all four shifts of a medium-sized city’s police department were tested using a within- and between-subjects design to assess the impact of fatigue on individual officers, as well as the impact of different work shifts, on post-shift driving performance. Controlled laboratory experiments were conducted during which participants drove high-fidelity driving training simulators on two occasions: immediately following five consecutive 10:40-hour patrol shifts (fatigued condition) and again 72 hours after completing the last shift in a work cycle (rested condition). Findings – Generalized linear mixed-model analyses of driving performance showed that officers working night shifts had significantly greater lane deviation during post-shift, non-operational driving than those working day shifts (F=4.40, df=1, 150, p=0.038). The same method also showed that easy to measure psychomotor vigilance test scores for reaction time predicted both lane deviation (F=31.48, df=1, 151, p < 0.001) and collisions (F=14.10, df=1, 151, p < 0.001) during the simulated drives. Research limitations/implications – Simulated driving tasks done by participants were generally less challenging than patrol or off-duty driving and likely underestimate the impact of fatigue on police driving post-shift or during extended shifts. Originality/value – This is the first experimental research to assess the impact of shiftwork, fatigue, and extended shifts on police post-shift drowsy driving, a known risk factor for shift workers in general.

Shift work and long-term injury among police officers

OBJECTIVE Our previous work has suggested that the incidence of any occurrence of injury leave among police officers is higher on night shifts. In this study, we extended our inquiry to determine whether the incidence of long-term injury leave varies across shifts. METHODS Police officers (N=419) from an urban department were included in the analysis. Daily payroll work history data from 1994-2010 was collected. Injury leave duration was examined ranging from ≥1-≥90 days. Poisson regression models were used to compute incidence rates (IR) and incidence rate ratios (IRR) of long-term injury. RESULTS Cumulative incidence of injury for different durations of leave defined as ≥1, ≥5, ≥10, ≥15, ≥30, and ≥90 days were 61.3%, 45.4%, 39.9%, 33.9%, 26.5%, and 9.6% respectively. Age-and gender adjusted IRR of long-term injury (≥90 days) for night versus day shifts was IRR 3.12, 95% confidence interval (95% CI) 1.35-7.21 and IRR 2.21, 95% CI 1.04-4.68, for night versus afternoon shifts. Among all durations examined, the largest IRR was for injury ≥90 days, night versus day shifts (IRR 3.12, 95% CI 1.35-7.21). CONCLUSIONS Night shift work was significantly associated with long-term injury among police officers after adjustment for age and gender. Although type of injury was not available, it is possible that variation in injury type across shifts might account for some of this association.

Human Nature and Crime Control: Improving the Feasibility of Nurturant Strategies

The same evolutionary and ecological principles that organize our understanding of organisms and organic communities can be used to help understand criminal behavior and our responses to it. This approach suggests solutions for an important dilemma that confronts the United States. The dilemma is that preoccupation with problems such as gang violence, drug abuse, and street crime increasingly diverts resources and attention away from child development problems associated with the health, education, and welfare of young people. Just as a consensus is emerging about the importance of balancing traditional criminal justice system approaches to crime control with nurturant approaches that address child development concerns, child development program resources are dwindling. This dynamic is driven by a vicious cycle of media sensationalism, political expediency, and public impatience that encourages ineffective “quick fixes” for crime. An evolutionary ecological approach to crime control suggests ways to reverse this vicious cycle and increase the political, programmatic, and economic feasibility of child development programs.