Sleep problems are a strong predictor of stress-related metabolic changes in police officers. A prospective study

RESEARCH ARTICLE Sleep problems are a strong predictor of stress-related metabolic changes in police officers. A prospective study Sergio Garbarino ID1,2,3‡, Nicola Magnavita ID1,4‡* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Post-graduate School of Occupational Health, Università Cattolica del Sacro Cuore, Rome, Italy, 2 State Police Health Service Department, Ministry of the Interior, Rome, Italy, 3 Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Maternal-Infantile Sciences (DINOGMI), Genoa, Italy, 4 Department of Woman/Child & Public Health, Fondazione Policlinico Gemelli IRCCS, Rome, Italy ‡ These authors are co-first authors on this work. * Abstract OPEN ACCESS Citation: Garbarino S, Magnavita N (2019) Sleep problems are a strong predictor of stress-related metabolic changes in police officers. A prospective study. PLoS ONE 14(10): e0224259. https://doi. org/10.1371/journal.pone.0224259 Editor: Juan Manuel Marquez-Romero, Instituto Mexicano del Seguro Social (IMSS) HGZ 2, MEXICO Received: April 16, 2019 Accepted: September 25, 2019 Published: October 22, 2019 Copyright: © 2019 Garbarino, Magnavita. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Data have been deposited on Zenodo, DOI: 10.5281/zenodo. 3376509. Funding: The Università Cattolica del Sacro Cuore of Rome contributed to the funding of this research project and its publication. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Objective Previous studies have shown that workers chronically exposed to occupational stress have an increased risk of metabolic syndrome (MetS) and sleep problems (SPs). The purpose of this study was to verify whether SPs mediate the relationship between stress and MetS. Method A 5-year prospective cohort study included 242 police officers from a rapid response unit engaged exclusively in maintaining law and order. Perceived stress levels were measured repeatedly with the demand-control-support and the effort-reward-imbalance questionnaires; insomnia symptoms were assessed with the Pittsburgh Sleep Quality Index; excessive daytime sleepiness was measured using the Epworth Sleepiness Scale. MetS and its components were evaluated at baseline and at follow-up. Results During 5-year follow-up period, 26 new cases of MetS were identified. Both occupational stress and SPs were significantly related to incident cases of MetS. Insomnia symptoms showed a highly significant association with MetS (aOR 11.038; CI95% 2.867–42.493). Mediation analysis confirmed that SPs mediate the relationship between stress and MetS. A reciprocal relationship was found between job stress and SPs. Work-related stress was a significant predictor of insomnia symptoms, short sleep duration, sleep dissatisfaction, and sleepiness. Compared to the reference group, police officers with SPs at baseline had significantly higher odds of reporting high stress at follow-up. PLOS ONE | https://doi.org/10.1371/journal.pone.0224259 October 22, 2019 1 / 19 Sleep, stress and metabolic syndrome Conclusion SPs play a mediating role in the relationship between occupational stress and MetS. Prevention of MetS must include the control of stress factors and an increase in the resilience of workers, but correct sleep hygiene is also an essential factor. Introduction Metabolic syndrome (MetS) is a cluster of metabolically related cardiovascular risk factors (obesity, insulin resistance, dyslipidaemia and hypertension) [1] that also predict a high risk of developing diabetes [2], cancer [3], and cognitive impairment [4]. MetS is highly prevalent and increasing in most parts of the world [5]. Chronic occupational stress is considered to be a risk factor for MetS [6–16]. A recent meta-analysis of longitudinal studies showed that work-related stress is associated with a significant increase in the pooled risk of metabolic syndrome (RR = 1.47; CI95% = 1.22–1.78) [17]. In a previous longitudinal study on a rapid response police unit we observed that police officers with high job strain had a higher adjusted risk of developing MetS (aOR = 2.68; CI95% = 1.08–6.70) and hypertriglyceridemia (aOR = 7.86; CI95% = 1.29–48.04) than their colleagues classified in the lowest quartile of work-related distress [18]. It is well known that sleep disorders, such as obstructive sleep apnea (OSAS), are associated with MetS [19, 20]. It would be interesting to determine whether alterations in the quantity and quality of sleep that can occur in working environments, regardless of the existence of morbid conditions such as OSAS, are able, if continued over time, to induce MetS. Studies that consider only sleep duration have produced inconsistent results. For example, short sleep duration proved to be an independent risk factor for MetS in longitudinal studies conducted in Korea [21], China [22], Canada [23] and Japan [24], while in an Iranian cohort study, long sleep duration increased the risk of MetS [25]. In a Swedish cohort, both short and long sleep durations, and problems with falling and staying asleep were linked to a higher prevalence of MetS [26]. In a sample of police officers, poor sleeping conditions, i.e. lack of sound sleep and shift sleep disorder, were associated with a high prevalence of MetS [27]. A recent review of existing cross-sectional studies [28] provided some evidence of a positive association between sleep quality, or some sleep complaints (difficulty in falling asleep, difficulty in maintaining sleep, and sleep inefficiency) and MetS. However, further studies based on a longitudinal design are needed to explore the causal relationship between sleep quality and MetS. Work is known to disturb sleep, due to occupational exposure to many stressors [29]. Some aspects of work organization, such as lack of control over work times [30], insufficient rest between shifts [31], psychosocial burden and night work [32] or shift work [33] are predictors of sleep problems. Exposure to workplace violence is also associated with a significant increase in the pooled risk of sleep problems [34]. More generally, there is evidence that psychosocial stress is associated with sleep problems [35], and that both sleep deprivation [36, 37] and low sleep quality [38–40] are associated with stress response. Due to considerable disparity in the results of existing studies, the degree to which the relationship between job stress and sleep symptoms is unidirectional or reciprocal is unclear. The questions to be answered in this study are: can the presence of sleep symptoms be a predictor of MetS, and in what way are sleep, stress and m (...truncated)