Shift Work Adaptation Among Police Officers: The BCOPS Study

Abstract

Few studies have examined shiftwork adaptation among police officers or potential differences in disease biomarkers among adapted and maladapted shiftworkers. This study characterized shiftwork adaptation among 430 police officers from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study. Police officers working fixed night shifts with symptoms characteristic of adaptation and maladaptation were identified using latent class analysis (n = 242). Two approaches were applied, one with police-specific symptoms and another using more general symptoms as shiftwork adaptation indicators. Biomarkers of inflammation, heart rate variability, and cardiometabolic risk were then compared between shiftwork adaptation groups, and with officers working day shifts, after adjusting for confounding. When analyses included police-specific symptoms, maladapted shiftworkers (n = 73) had more self-reported stress, sleep disturbances, fatigue, and less social support than adapted shiftworkers (n = 169). Using more general symptoms, maladapted officers (n = 56) reported more stress and depression, and less social support than adapted officers (n = 186). In police-specific models, adjusted (least-squares) means (± standard error) of circulating interleukin-6 (IL-6) concentrations in maladapted officers (0.8 ± 0.1 ln[pg/ml]) were modestly elevated relative to adapted shiftworkers (0.7 ± 0.1 ln[pg/ml], p = .09) and relative to permanent day workers (0.5 ± 0.1 ln[pg/ml], p ≤ 0.01), and leptin levels in maladapted officers (9.6 ± 0.1 ln[pg/ml]) exceeded those in the adapted (9.4 ± 0.1 ln[pg/ml], p ≤ 0.01) and day shift groups (9.4 ± 0.1 ln[pg/ml], p = .03). In the general model, adjusted mean tumor necrosis factor-alpha (TNF-α) concentrations among maladapted officers (5.6 ± 0.23 pg/ml) exceeded the adapted (4.8 ± 0.2 pg/ml, p ≤ 0.01) and day workers (5.0 ± 0.2 pg/ml, p = .04), and insulin among maladapted officers was higher (2.4 ± 0.1 ln[uu/ml]) than the adapted group (1.8 ± 0.1 ln[uu/ml], p = .03). No differences were observed for the other biomarkers. The results suggest that maladaptation among police officers working fixed night shifts may lead to increases in leptin, insulin, IL-6, and TNF-α; however, the cross-sectional design and possible residual confounding preclude interpretation of cause and effect. Prospective studies are planned to further characterize the relationship between shiftwork maladaptation and biomarkers of chronic disease risk in this police officer cohort.

Keywords: Police officers; metabolic and immune system biomarkers; shiftwork adaptation and maladaptation; sleep; stress.

Figure 1.

Prevalence of latent class membership and item-response probabilities among the symptom indicator variables evaluated for their contribution to adaptation or maladaptation among shiftworking police officers (Police-specific model), BCOPS study, Buffalo, NY, USA, 2004–2005 (n = 242) The item-response probabilities represent the conditional probability that an officer would have a maladaptive response to an indicator variable. For example, the probability that an officer in the adapted shiftwork group reports sleep disturbance ≥twice per week is 0.19 and 0.55 for a maladapted officer. Indicator variables are components of the PSQI, SPPS, and VE questionnaires.

Figure 2.

Prevalence of latent class membership and item-response probabilities among the symptom indicator variables evaluated for their contribution to adaptation or maladaptation among shiftworking police officers (General symptom model), BCOPS study, Buffalo, NY, USA, 2004–2005 (n = 242). The item-response probabilities represent the conditional probability that an officer would have a maladaptive response to an indicator variable. For example, the probability that an officer in the adapted shiftwork group reports low social support is 0.37 and 0.78 for a maladapted officer. Indicator variables are components of SS, PSS, CESD, and VE questionnaires.