Shift work and the relationship with metabolic syndrome in Chinese aged workers

Associations of coal mine dust exposure with arterial stiffness and atherosclerotic cardiovascular disease risk in chinese coal miners

OBJECTIVE

Whether coal mine dust exposure increases cardiovascular diseases (CVDs) risk was rarely explored. Our objective was to examine the association between coal mine dust exposure and cardiovascular risk.

METHODS

We estimated cumulative coal mine dust exposure (CDE) for 1327 coal miners by combining data on workplace dust concentrations and work history. We used brachial-ankle pulse wave velocity (baPWV, a representative indicator of arterial stiffness) and ten-year atherosclerotic cardiovascular disease (ASCVD) risk to assess potential CVD risk, exploring their associations with CDE.

RESULTS

Positive dose-response relationships of CDE with baPWV and ten-year ASCVD risk were observed after adjusting for covariates. Specifically, each 1 standard deviation (SD) increase in CDE was related to a 0.27 m/s (95% CI: 0.21, 0.34) increase in baPWV and a 1.29 (95% CI: 1.14, 1.46) elevation in OR (odds ratio) of risk of abnormal baPWV. Moreover, each 1 SD increase in CDE was associated with a 0.74% (95% CI: 0.63%, 0.85%) increase in scores of ten-year ASCVD and a 1.91 (95% CI: 1.62, 2.26) increase in OR of risk of ten-year ASCVD. When compared with groups unexposed to coal mine dust, significant increase in the risk of arterial stiffness and ten-year ASCVD in the highest CDE groups were detected.

CONCLUSION

The study suggested that cumulative exposure to coal mine dust was associated with elevated arterial stiffness and ten-year ASCVD risk in a dose-response manner. These findings contribute valuable insights for cardiovascular risk associated with coal mine dust.

Effects of Nightshift Work on Blood Metabolites in Female Nurses and Paramedic Staff: A Cross-sectional Study

Nightshift work disturbs the circadian rhythm, which might contribute to the development of cardio-metabolic disorders. In this cross-sectional study, we aimed to gain insight into perturbations of disease relevant metabolic pathways due to nightshift work. We characterized the metabolic profiles of 237 female nurses and paramedic staff participating in the Klokwerk study using the Nightingale Health platform. We performed analyses on plasma levels of 225 metabolites, including cholesterol, triglycerides, fatty acids, and amino acids. Using both principal component- and univariate-regression, we compared metabolic profiles of nightshift workers to metabolic profiles from workers that did not work night shifts (defined as day workers). We also assessed whether differential effects were observed between recently started versus more experienced workers. Within the group of nightshift workers, we compared metabolic profiles measured right after a nightshift with metabolic profiles measured on a day when no nightshift work was conducted. We observed evidence for an impact of nightshift work on the presence of unfavorable fatty acid profiles in blood. Amongst the fatty acids, effects were most prominent for PUFA/FA ratios (consistently decreased) and SFA/FA ratios (consistently elevated). This pattern of less favorable fatty acid profiles was also observed in samples collected directly after a night shift. Amino acid levels (histidine, glutamine, isoleucine, and leucine) and lipoproteins (especially HDL-cholesterol, VLDL-cholesterol, and triglycerides) were elevated when comparing nightshift workers with day workers. Amino acid levels were decreased in the samples that were collected directly after working a nightshift (compared to levels in samples that were collected during a non-nightshift period). The observed effects were generally more pronounced in samples collected directly after the nightshift and among recently started compared to more experienced nightshift workers. Our finding of a suggested impact of shift work on impaired lipid metabolism is in line with evidence that links disruption of circadian rhythmicity to obesity and metabolic disorders.

Impaired Melatonin Secretion, Oxidative Stress and Metabolic Syndrome in Night Shift Work

Metabolic syndrome has been associated in many studies with working in shifts. Even if the mechanistic details are not fully understood, forced sleep deprivation and exposure to light, as happens during night shifts, or irregular schedules with late or very early onset of the working program, lead to a sleep-wake rhythm misalignment, metabolic dysregulation and oxidative stress. The cyclic melatonin secretion is regulated by the hypothalamic suprachiasmatic nuclei and light exposure. At a central level, melatonin promotes sleep and inhibits wake-signals. Beside this role, melatonin acts as an antioxidant and influences the functionality of the cardiovascular system and of different metabolic processes. This review presents data about the influence of night shifts on melatonin secretion and oxidative stress. Assembling data from epidemiological, experimental and clinical studies contributes to a better understanding of the pathological links between chronodisruption and the metabolic syndrome related to working in shifts.

Cardiometabolic function in retired night shift workers and retired day workers

Night shift work is associated with poor cardiometabolic outcomes, even post-retirement. However, the characteristics of cardiometabolic function in retired night shift workers (RNSW) compared to retired day workers (RDW) are not well-understood. Rigorous characterization of cardiometabolic dysfunction in RNSW and RDW will inform targeted risk stratification for RNSW. This observational study evaluated whether RNSW (n = 71) had poorer cardiometabolic function than RDW (n = 83). We conducted a multimodal assessment of cardiometabolic function including metabolic syndrome prevalence, brachial artery flow-mediated dilation, and carotid intima-media thickness. Main analyses tested overall group differences. Sex-stratified follow-up analyses tested group differences separately in men and women. RNSW had 2.6-times higher odds of metabolic syndrome prevalence than RDW in unadjusted analyses (95% CI  [1.1,6.3]); this association was not significant when adjusting for age, race and education. RNSW and RDW (Mage = 68.4; 55% female) did not differ in percent flow-mediated dilation or carotid intima-media thickness. In sex-stratified analyses, women RNSW had 3.3-times higher odds of having high body mass index than women RDW (95% CI  [1.2,10.4]). Men RNSW had 3.9-times higher odds of having high triglycerides than men RDW (95% CI [1.1,14.2]). No other group differences were observed. We found mixed evidence that night shift work exposure was associated with cardiometabolic dysfunction in retirement, possibly in a sex-specific manner.

Association between Shift Work and Metabolic Syndrome: A 4-Year Retrospective Cohort Study

(1) Background: Previous studies on the association between shift work and metabolic syndrome have had inconsistent results. This may be due to the cross-sectional study design and non-objective data used in those studies. Hence, this study aimed to identify risk factors for Metabolic syndrome using objective information provided by the relevant companies and longitudinal data provided in health examinations. (2) Methods: In total, 1211 male workers of three manufacturing companies, including shift workers, were surveyed annually for 4 years. Data on age, smoking, drinking, physical activity, length of shift work, type of shift, past history, waist circumference, blood pressure, blood sugar, triglyceride, and high-density cholesterol (HDL) were collected and analyzed using generalized estimating equations (GEE) to identify the risk factors for Metabolic syndrome. (3) Results: In the multivariate analysis of Metabolic syndrome risk factors, age (OR = 1.078, 95% CI: 1.045–1.112), current smoking (OR = 1.428, 95% CI: 1.815–5.325), and BMI (OR = 1.498, 95% CI: 1.338–1.676) were statistically significant for day workers (n= 510). Additionally, for shift workers (N = 701), age (OR = 1.064, 95% CI: 1.008–1.174), current smoking (OR = 2.092, 95% CI: 1.854–8.439), BMI (OR = 1.471, 95% CI: 1.253–1.727) and length of shift work (OR = 1.115, 95% CI: 1.010-1.320) were statistically significant. Shift work was associated with a higher risk of Metabolic syndrome (OR = 1.093, 95% CI: 1.137–2.233) compared to day workers. For shift workers, shift work for more than 20 years was associated with Metabolic syndrome (OR = 2.080, 95% CI: 1.911–9.103), but the dose–response relationship was not statistically significant. (4) Conclusions: This study revealed that age, current smoking, BMI, and shift work are potential risk factors for Metabolic syndrome. In particular, the length of shift work (>20 years) is a potential risk factor for Metabolic syndrome in shift workers. To prevent metabolic syndrome in shift workers, health managers need to actively accommodate shift workers (especially those who have worked for more than 20 years), current smokers, and obese people. A long-term cohort study based on objective data is needed to identify the chronic health impact and the risk factors of shift work.

Prediction of risk of coronary artery disease based on the Framingham risk score in association with shift work among nurses

Objectives. This study aimed to determine the prediction of risk of coronary artery disease (CAD) based on the Framingham risk score (FRS) in association with shift work among nurses.Methods. This cross-sectional and descriptive-analytic study was conducted with nurses working in three hospitals located in Abadan, southwest Iran. The sample size was 120 participants, divided into 60 shift workers and 60 day workers (non-shift workers). Demographic data and medical and occupational history were collected through a checklist and interviews. CAD risk assessment tools used to estimate the 10-year cardiovascular disease (CVD) risk included the FRS. Data were analysed by Mann-Whitney U test, χ² test and one-way analysis of variance (ANOVA) using SPSS version 22.0.Results. There were statistically significant differences between blood pressure (BP), total cholesterol (TC), body mass index (BMI) and shift work (p ≤ 0.001). There was a statistically significant difference between prevalence of CAD risk and shift work based on the FRS (p = 0.04).Conclusion. The study findings showed that shift work is a risk factor for CAD disturbances. Therefore, particular follow-up of shift workers should be recommended for screening and preventing CAD.

Chrononutrition-When We Eat Is of the Essence in Tackling Obesity

Obesity is a chronic and relapsing public health problem with an extensive list of associated comorbidities. The worldwide prevalence of obesity has nearly tripled over the last five decades and continues to pose a serious threat to wider society and the wellbeing of future generations. The pathogenesis of obesity is complex but diet plays a key role in the onset and progression of the disease. The human diet has changed drastically across the globe, with an estimate that approximately 72% of the calories consumed today come from foods that were not part of our ancestral diets and are not compatible with our metabolism. Additionally, multiple nutrient-independent factors, e.g., cost, accessibility, behaviours, culture, education, work commitments, knowledge and societal set-up, influence our food choices and eating patterns. Much research has been focused on 'what to eat' or 'how much to eat' to reduce the obesity burden, but increasingly evidence indicates that 'when to eat' is fundamental to human metabolism. Aligning feeding patterns to the 24-h circadian clock that regulates a wide range of physiological and behavioural processes has multiple health-promoting effects with anti-obesity being a major part. This article explores the current understanding of the interactions between the body clocks, bioactive dietary components and the less appreciated role of meal timings in energy homeostasis and obesity.

Eating Patterns among Emergency Medical Service Providers in the United States: A Qualitative Interview Study

Emergency medical service (EMS) providers experience demanding work conditions in addition to shift work, which increases risk for nutrition related chronic disease such as metabolic syndrome, diabetes, obesity, and cardiovascular disease. The high stress, emergent, and unpredictable nature of EMS may interfere with healthy eating patterns on and off shift, however little is known about how these conditions impact dietary patterns among EMS providers. This study aimed to understand factors impacting dietary patterns through semi-structured interviews with 40 EMS providers throughout the United States. Interviews were conducted virtually via Zoom video conference. Inductive coding was used to identify themes throughout the interviews. Salient factors mentioned in the interviews included hunger, fatigue, stress, coworker influence, ambulance posting, geographical location, agency policy, and culture. Factors were grouped into 4 domains: physiological factors, psychosocial factors, physical environment, and organizational environment, represented by an adapted version of the social ecological model of health behaviors to include factors influencing eating patterns specific to EMS, which may contribute to overall health. Various barriers to healthy eating exist within EMS, and future studies should explore interventions at each level of our proposed model to improve conditions and reduce nutrition related disease risk in this essential population.

Night Shift Work, Genetic Risk, and Hypertension

OBJECTIVE

To perform a prospective cohort study to investigate whether night shift work is associated with incident hypertension and whether this association is modified by genetic susceptibility to hypertension because evidence on the association between night shift work and hypertension is insufficient.

METHODS

A total of 232,665 participants of UK Biobank who were recruited from 2006 to 2010 and observed to January 31, 2018, were included in this study. A Cox proportional hazards model with covariate adjustment was performed to assess the association between night shift work exposure and hypertension risk. We constructed a polygenic risk score (PRS) for genetic susceptibility to hypertension, which was used to explore whether genetic susceptibility to hypertension modified the effect of night shift work. The robustness of the results was assessed by sensitivity analysis.

RESULTS

Night shift workers had a higher hypertension risk than day shift workers, which increased with increasing frequency of night shift work (P_trend<.001). The association was attenuated but still remained statistically significant in the fully adjusted model. We explored the joint effect of night shift work and genetic susceptibility on hypertension. Permanent night shift workers with higher hypertension PRSs had higher risk of hypertension than day workers with low PRSs.

CONCLUSION

Night shift work exposure was associated with increased hypertension risk, which was modified by the genetic risk for hypertension, indicating that there is a joint effect of night shift work and genetic risk on hypertension.

Sleep duration and metabolic body size phenotypes among Chinese young workers

The evidence linking sleep duration and metabolic body size phenotypes is limited, especially in young adulthood. In this study, we aimed to examine the association between sleep duration and metabolic body size phenotypes among Chinese young workers and investigate whether discrepancies exist among shift and non-shift workers. A cross-sectional study was performed between 2018 and 2019 in Wuhan, China and 7,376 young adults aged 20-35 years were included. Self-reported sleep duration was coded into four groups: <7, 7-8, 8-9, and ≥9 h per day. Participants were classified into four metabolic body size phenotypes according to their body mass index and metabolic health status: metabolically healthy normal weight, metabolically unhealthy normal weight, metabolically healthy overweight/obesity (MHO), and metabolically unhealthy overweight/obesity (MUO). Multinomial logistic regression models were used to explore the associations between sleep duration and metabolic body phenotypes. Compared with those who slept 7-8 h each night, those with sleep duration <7 h per day had higher odds of MHO (OR 1.27, 95% CI: 1.02-1.56) and MUO (OR 1.22, 95% CI: 1.03-1.43), irrespective of multiple confounders. Stratification analyses by shift work showed that the association between short nighttime sleep and increased odds of MUO was only observed in shift workers (OR 1.26, 95% CI 1.03-1.54). Sleep duration is independently associated with metabolic body size phenotypes among Chinese young adults, while shift work could possibly modulate the association. These results may provide evidence for advocating adequate sleep toward favorable metabolic body size phenotypes in young workers.

Metabolic syndrome and its relationship with shift work in petrochemical workers

BACKGROUND: The metabolic syndrome is a complex of interdependent risk factors for cardiovascular disease and diabetes. Shift work might have an impact on metabolic variables, and be a risk factor for type 2 diabetes. To date, only few studies have been done on the prevalence of MetS in industrial work environments in Iran, and most of them have been conducted on a small sample size. OBJECTIVE: The aim of this study was to evaluate the impact of shift work on prevalence of metabolic syndrome in one of the petrochemical companies in Iran. METHODS: This cross-sectional study was conducted among 692 male workers of a petrochemical company in south-west Iran. Metabolic syndrome was diagnosed according to criteria recommended by Adult Treatment Panel III. In order to determine correlation between MetS and its factors with shift work odds ratio (ORs) for the MetS, 95% confidence level (95% CL), chi-square test and logistic regression analysis were performed. RESULTS: Overall 15.1% of workers were diagnosed with metabolic syndrome and 80% of them were shift workers. A significant difference for prevalence of metabolic syndrome and mean values for body mass index, blood pressure, fast blood sugar, waist circumference among shift workers and non-shift workers were identified (p < 0.001). Compared with the day workers, shift workers had a significantly higher risk of MetS (odds ratio = 4.852; 95% CI 2.34–9.974). CONCLUSIONS: There is an association between metabolic syndrome and shift work in petrochemical workers. Promising intervention strategies are needed for prevention of metabolic disorders for shift workers.

Lack of food intake during shift work alters the heart transcriptome and leads to cardiac tissue fibrosis and inflammation in rats

Background

Many epidemiological studies revealed that shift work is associated with an increased risk of a number of pathologies, including cardiovascular diseases. An experimental model of shift work in rats has additionally been shown to recapitulate aspects of metabolic disorders observed in human shift workers, including increased fat content and impaired glucose tolerance, and used to demonstrate that restricting food consumption outside working hours prevents shift work-associated obesity and metabolic disturbance. However, the way distinct shift work parameters, such as type of work, quantity, and duration, affect cardiovascular function and the underlying mechanisms, remains poorly understood. Here, we used the rat as a model to characterize the effects of shift work in the heart and determine whether they can be modulated by restricting food intake during the normal active phase.

Results

We show that experimental shift work reprograms the heart cycling transcriptome independently of food consumption. While phases of rhythmic gene expression are distributed across the 24-h day in control rats, they are clustered towards discrete times in shift workers. Additionally, preventing food intake during shift work affects the expression level of hundreds of genes in the heart, including genes encoding components of the extracellular matrix and inflammatory markers found in transcriptional signatures associated with pressure overload and cardiac hypertrophy. Consistent with this, the heart of shift worker rats not eating during work hours, but having access to food outside of shift work, exhibits increased collagen 1 deposition and displays increased infiltration by immune cells. While maintaining food access during shift work has less effects on gene expression, genes found in transcriptional signatures of cardiac hypertrophy remain affected, and the heart of shift worker rats exhibits fibrosis without inflammation.

Conclusions

Together, our findings unraveled differential effects of food consumption on remodeled transcriptional profiles of the heart in shift worker rats. They also provide insights into how shift work affects cardiac function and suggest that some interventions aiming at mitigating metabolic disorders in shift workers may have adverse effects on cardiovascular diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01256-9.

Impact of night and shift work on metabolic syndrome and its components: a cross-sectional study in an active middle-to-older-aged population-based sample

OBJECTIVES

To examine the effects of work schedules on metabolic syndrome and its components in active middle-to-older-aged workers.

METHODS

A cross-sectional analysis including middle-to-older-aged active workers from the population-based CoLaus|PsyCoLaus study (Lausanne, Switzerland) was performed. Work schedule was self-reported and defined as follows: permanent day, day shift, night shift and permanent night work. Associations between work schedule and the risk of metabolic syndrome and its components were analysed using multivariable-adjusted logistic regressions.

RESULTS

A total of 2301 active workers (median age (IQR): 55.4 (50.8 to 60.4), 50.1% women) were included. Of these, 1905 were permanent day workers, 220 were day-shift workers, 134 were night-shift workers and 42 were permanent night-shift workers. There were significant interactions between sex and work schedule for metabolic syndrome, high triglycerides and visceral obesity. Men but not women permanent night workers had a higher prevalence of metabolic syndrome than permanent day workers in multivariable-adjusted analyses (OR 4.45 (95% CI 1.36 to 14.56)). Analysis of metabolic syndrome subcomponents showed that the association between work schedule and metabolic syndrome in men was mainly driven by visceral obesity (OR 3.35 (95% CI 1.04 to 10.76)). Conversely, women but not men working in night shift were at increased risk of having high triglycerides compared with permanent day workers (OR 2.92 (95% CI 1.03 to 8.27)).

CONCLUSIONS

The risk of metabolic syndrome is higher in men working in permanent night shift compared with permanent day work, and this association could be mediated by visceral obesity.

Rest-Activity Rhythm Is Associated With Obesity Phenotypes: A Cross-Sectional Analysis

BACKGROUND

The prevalence of obesity continues to increase in spite of substantial efforts towards its prevention, posing a major threat to health globally. Circadian disruption has been associated with a wide range of preclinical and clinical disorders, including obesity. However, whether rest-activity rhythm (RAR), an expression of the endogenous circadian rhythm, is associated with excess adiposity is poorly understood. Here we aimed to assess the association of RAR with general and abdominal obesity.

METHODS

Non-institutionalized adults aged ≥20 years participating in the US National Health and Nutrition Examination Survey (NHANES) 2011-2014 who wore accelerometers for at least four 24-hour periods were included (N=7,838). Amplitude, mesor, acrophase and pseudo-F statistic of RAR were estimated using extended cosinor model, and interdaily stability (IS) and intradaily variability (IV) were computed by nonparametric methods. We tested the association between rest-activity rhythm and general obesity defined by body mass index and abdominal obesity by waist circumference. Waist-to-height ratio, sagittal abdominal diameter, and total and trunk fat percentages measured by imaging methods were also analyzed.

RESULTS

In multivariable analysis, low amplitude (magnitude of the rhythm), mesor (rhythm-corrected average activity level), pseudo-F statistic (robustness of the rhythm), IS (day-to-day rhythm stability), or high IV (rhythm fragmentation) were independently associated with higher likelihood of general or abdominal obesity (all Ps<.05). Consistently, RAR metrics were similarly associated with all adiposity measures (all Ps<.01). Delayed phase of RAR (later acrophase) was only significantly related to general and abdominal obesity in women.

CONCLUSIONS

Aberrant RAR is independently associated with anthropometric and imaging measures of general and abdominal obesity. Longitudinal studies assessing whether RAR metrics can predict weight gain and incident obesity are warranted.

Night shift work and the risk of metabolic syndrome: Findings from an 8-year hospital cohort

Objectives

Studies concerning the risk of metabolic syndrome associated with night work have shown inconsistent findings, due to imprecise working time data and cross-sectional design. We used register-based daily working time data to examine the risk of incident metabolic syndrome associated with night shift work.

Methods

Working time data collected between 2010 and 2018 of 5775 Taiwanese hospital workers were used to identify night shift workers and to calculate the number of night shifts. Metabolic syndrome was identified by annual occupational health examination results, which were linked to the working time data. Logistic regression models and generalized estimating equations were used to examine the association between night shift work and metabolic syndrome and the 5 components of metabolic syndrome.

Results

Night shift work is associated with a higher risk of developing metabolic syndrome (adjusted OR = 1.36, 95% CI = 1.04 to 1.78) and high waist circumference (adjusted OR = 1.27, 95% CI = 1.07 to 1.78) compared to day work. Among night shift workers, increased number of night shifts was associated with high blood pressure (adjusted OR = 1.15, 95% CI = 1.01 to 1.31).

Conclusions

Night shift work is associated with metabolic risk factors. Long-term effects of circadian rhythm disruption on metabolic disturbances needs to be further studied.

The effects of dyslipidemia on noise-induced hearing loss in a petrochemical workers in the Southwest of Iran

BACKGROUND

Research has shown that the decrease in the inner diameter of vessels caused by hyperlipidemia lowers the capacity for blood oxygen delivery to the cochlea. This leads to impaired cochlear metabolism and causes hearing problems.

OBJECTIVE

The effects of dyslipidemia on noise-induced hearing loss in workers were examined.

METHODS

This descriptive cross-sectional study was performed on 692 male employees in a petrochemical industry in the southwest of Iran exposed to 85 dB noise. Clinical audiometry and blood sample tests were used to evaluate the hearing and prevalence indices of dyslipidemia (cholesterol, triglyceride, HDL and LDL). The data were analyzed using SPSS software version 25 (p = 0.05).

RESULTS

The results showed that the prevalence of dyslipidemia was 24.5%with abnormal relative triglyceride frequency of 49.5%, HDL of 28%, LDL of 33%, and total blood cholesterol level of 37.8%. There was no significant relationship between NIHL and dyslipidemia (p >  0.09). However, the major NIHL drops at different frequencies were in the individuals with dyslipidemia. The parameters age and dyslipidemia increased NIHL odds ratio (95%C.I.). by 1.130 (1.160-1.100) and 1.618 (2.418-1.082) respectivelyCONCLUSION:The rate of hearing loss in individuals with dyslipidemia increases at different frequencies and it leads to an increase of the OR of NIHL in individuals with dyslipidemia. We can control dyslipidemia and its effective factors. The NIHL is more common in people exposed to noise.

Is Shift Work Sleep Disorder a Risk Factor for Metabolic Syndrome and Its Components? A Systematic Review of Cross-Sectional Studies

Shift work sleep disorder is prevalent in night shift workers due to prolonged misalignment of the circadian rhythm. Night shift workers comprise a significant portion of the workforce and it is important to study the potential implications on their health. Studies have shown the association of metabolic syndrome (MetS) and the components, that is, obesity, dyslipidemia, hypertension, and insulin resistance, with shift workers. Nocturnal exposure to bright light can affect various physiological processes including melatonin secretion, which is a regulator in insulin synthesis. A systematic review was conducted to identify studies showing the association between shift work and MetS and/or its components, as well as to review the pathophysiology for further investigations. This review follows the guidelines as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist 2009. One thousand nine hundred ten records were identified from the PubMed database using both keywords and medical subject headings terms. After applying the inclusion/exclusion and eligibility criteria, 18 observational studies were included in the qualitative synthesis. Quality appraisal was conducted by two investigators independently using the Newcastle/Ottawa Scale, and 11 articles were finalized for the review after scoring 60% and above. Each study measured the different components of MetS and/or the presence of MetS. Statistically significant results were reported for the association between shift work and MetS, shift work and obesity, shift work and dyslipidemia, shift work and hypertension, and shift work and insulin resistance. This review identifies a need to emphasize treatment plans for shift workers to manage not only sleep disorders but other chronic diseases such as MetS, obesity, hypertension, dyslipidemia, and insulin resistance.

Actigraphy-derived rest-activity rhythms are associated with nocturnal blood pressure in young women

INTRODUCTION

Misalignment between lifestyle behaviors and endogenous circadian rhythms is associated with elevated nocturnal blood pressure (BP) in experimental studies; however, less is known about free-living (i.e. nonlaboratory) circadian disruption and nocturnal BP. Additionally, sex-specific cardiovascular implications of circadian disruption are unclear.

OBJECTIVE

To examine the associations between rest--activity rhythms (RAR), a field-based estimate of circadian disruption, and nocturnal BP characteristics in male and female young adults.

METHODS

Fifty participants (20 ± 1 years; 20 men/30 women) underwent 24-h ambulatory BP monitoring following 14 days of wrist actigraphy. RAR variables of interdaily stability (day-to-day consistency in RAR), intradaily variability (within-day fragmentation of RAR), and relative amplitude (difference between peak vs. trough activity) were derived from actigraphy. Multivariable regression models of mean nocturnal SBP, DBP, and SBP dipping were generated to test main associations with RAR variables, and sex × RAR interactions. Daytime BP, race, BMI, physical activity, sleep duration, alcohol, caffeine, and sodium intake were considered as covariates.

RESULTS

In the full sample, no main associations between RAR and nocturnal BP characteristics were found. Sex interacted with RAR such that in women, higher interdaily stability (β = -5.39, 95% CI = -10.04 to -0.73, P = 0.024) and relative amplitude (β = -4.78, 95% CI = -9.22 to -0.34, P = 0.036) were both associated with lower nocturnal SBP. Sex-stratified multivariable models of nocturnal BP also revealed associations between interdaily stability and relative amplitude with SBP dipping in women (all P ≤ 0.01). No associations were apparent in men.

CONCLUSION

Consistent and high-amplitude RAR are favorably associated with nocturnal BP characteristics in young female adults.

Association between shift work or long working hours with metabolic syndrome: a systematic review and dose-response meta-analysis of observational studies

This meta-analysis investigates the relationship between both shift work and long working hours and risk of developing metabolic syndrome (MetS). PubMed, EMBASE, and Web of Science databases were searched from the outset to December 10, 2019. Two reviewers independently screened studies, extracted data, and assessed the risk of bias of included studies. A total of 36 (30 cross-sectional, 5 cohort, and a nested case-control) studies, involving 274,263 participants, were included. The pooled odds ratio of shift work and development of MetS was 1.35 (95% confidence interval: 1.24-1.48), and the pooled odds ratio of long working hours and development of MetS was 1.19 (95% confidence interval: 0.97-1.46). In the subgroup analysis stratified by gender, the pooled odds ratios for male and female shift workers were 1.25 (95% confidence interval: 1.14-1.37) and 1.47 (95% confidence interval: 1.18-1.82), respectively. The dose-response (number of years of shift work and development of MetS) analysis showed the pooled odds ratio for 5 years of shift work was 1.07 (95% confidence interval: 1.05-1.09) and for 10 years of shift work 1.11 (95% confidence interval: 1.06-1.15). Our meta-analysis confirmed shift work is significantly associated with risk of metabolic syndrome, but the relationship between long working hours and MetS was not substantiated. Additionally, there was a nonlinear dose-response relationship between the number of years of shift work and risk of MetS, showing positive relationship to about 20 years of shift work but not for longer than 20 years. Prospective cohort studies regarding specific shift work schedules are needed to confirm these results.

Circadian dysynchrony among nurses performing shift work at a tertiary care teaching hospital: a preliminary study

BACKGROUND

Circadian rhythm is intracellular molecular mechanisms, influenced by environmental factors such as light, noise, mealtime, and sleep pattern. Shift work affects the sleep pattern, mealtime and psychological aspects of workers. This study aims to compare the effect of shift work on circadian dysynchrony among nurses in two different groups based on the duration of shift work.

MATERIAL AND METHOD

It was a cross-sectional, preliminary study done at a tertiary care teaching hospital in North India. The study enrolled 170 nurses (aged <35 years) performing shift duties for last 3 years (group-1) and 1 year (group-2) respectively in a 1:1 ratio. Tools used to collect data were case reporting form (demographic and clinical variables, anthropometric measures), Hamilton Anxiety Rating Scale, and Pittsburg Sleep Quality Index.

RESULTS

Mean age of participants was 27.39±2.89 vs. 26.14±2.45 in group 1 and 2. We found significant positive correlation of duration of shift work with diastolic blood pressure (DBP) (P=0.000), systolic blood pressure (SBP) (P=0.001), body fat % (P=0.019), weight (P=0.034), hip circumference (HC) (P=0.000) and also significant difference between means of DBP (P=0.001) and HC (P=0.003) in both groups. Whereas bad sleep quality was found in 79% and 66% of participants in group 1 and 2 respectively, the prevalence of moderate to severe anxiety in groups 1 and 2 was 60% and 37% respectively.

CONCLUSION

Long duration of shift work increases the risk of developing cardiometabolic risk factors as a consequence of circadian dysynchrony and varies with the duration of shift work.

Behavioural characteristics and abdominal obesity among Brazilian shift working women

OBJECTIVE

To explore the association between behavioural characteristics with the prevalence of abdominal obesity (AO) among a population of Southern Brazilian shift working women.

DESIGN

A cross-sectional study was conducted. AO was estimated using waist circumference (WC), and it was used to classify women as having AO (WC ≥ 88 cm). Prevalence ratios were estimated using Poisson regression with robust variance.

SETTING

A large plastic utensils company in Southern Brazil.

PARTICIPANTS

450 female shift workers.

RESULTS

The prevalence of the AO in the women shift workers was 44·5 % (95 % CI 40·0, 49·2 %). In night shift workers, the prevalence of AO was 56·1 % compared with 40·9 % among hybrid shift workers. After adjustments for covariates, women who were current smokers had a decrease in the prevalence of AO compared with those who never smoked. Women who had three or fewer meals per day had a 46 % increase in the AO prevalence compared with those eating more frequent meals. Night shift work was associated with increase in AO prevalence compared with hybrid shift (PR 1·33; 95 % CI: 1·08, 1·64).

CONCLUSIONS

Our findings indicate that behavioural characteristics are associated with a high prevalence of AO in female shift workers, thus suggesting that behavioural modifications among women working shifts, such as increase in meal frequency and physical activity, may reduce AO.

Role of the Immune System and the Circadian Rhythm in the Pathogenesis of Chronic Pancreatitis: Establishing a Personalized Signature for Improving the Effect of Immunotherapies for Chronic Pancreatitis

Pancreatitis, in both acute and chronic forms, poses a major therapeutic challenge and is associated with great morbidity and several complications. The nature of pancreatic injury in chronic pancreatitis (CP) and the wide range of causative processes that lead to CP have made effective therapy a true unmet need. Multiple physiological, genetic, environmental, and behavioral factors contribute to the development of CP. As a result, several fields of research are aimed at identifying and addressing the factors that contribute to pancreatic injury. In this article, we review the current understanding of the pathogenesis and natural history of CP. We focus on the autonomous nervous system, immune system, and role of a chronobiological therapeutic approach to alleviate symptoms and prevent or reverse pancreatic injury associated with CP. We aim to demonstrate that individualizing chronopharmacological treatments for CP is a promising direction for future treatment using immune, nervous, and circadian systems.

Consequences of Circadian Disruption in Shift Workers on Chrononutrition and their Psychosocial Well-Being

The workers and employees in various institutions are subjected to different shifts and work schedules. The employees work not only at daytime but also during odd hours at night. The biological clock of an individual is often altered during night shifts. This affects the psychosocial well-being and circadian nutritional intake of the worker. Disturbance in circadian rhythm results in the development of metabolic disorders such as hypertension, dyslipidemia, dysglycemia, and abdominal obesity. In the present review, we discuss the nature of shift work, sleep/wake cycle of an individual, chrononutrition, dietary habits, and meal changes with regard to timing and frequency, related to shift work. We also discuss the relationship between nutritional intake and psychosocial well-being among shift workers. The review may be beneficial for prevention of metabolic disorders and maintaining sound psychological condition in shift workers.

Sex differences in the circadian misalignment effects on energy regulation

Shift work causes circadian misalignment and is a risk factor for obesity. While some characteristics of the human circadian system and energy metabolism differ between males and females, little is known about whether sex modulates circadian misalignment effects on energy homeostasis. Here we show-using a randomized cross-over design with two 8-d laboratory protocols in 14 young healthy adults (6 females)-that circadian misalignment has sex-specific influences on energy homeostasis independent of behavioral/environmental factors. First, circadian misalignment affected 24-h average levels of the satiety hormone leptin sex-dependently (P < 0.0001), with a ∼7% decrease in females (P < 0.05) and an ∼11% increase in males (P < 0.0001). Consistently, circadian misalignment also increased the hunger hormone ghrelin by ∼8% during wake periods in females (P < 0.05) without significant effect in males. Females reported reduced fullness, consistent with their appetite hormone changes. However, males reported a rise in cravings for energy-dense and savory foods not consistent with their homeostatic hormonal changes, suggesting involvement of hedonic appetite pathways in males. Moreover, there were significant sex-dependent effects of circadian misalignment on respiratory quotient (P < 0.01), with significantly reduced values (P < 0.01) in females when misaligned, and again no significant effects in males, without sex-dependent effects on energy expenditure. Changes in sleep, thermoregulation, behavioral activity, lipids, and catecholamine levels were also assessed. These findings demonstrate that sex modulates the effects of circadian misalignment on energy metabolism, indicating possible sex-specific mechanisms and countermeasures for obesity in male and female shift workers.

The effects of rotating and extended night shift work on the prevalence of metabolic syndrome and its components

BACKGROUND

Some studies indicated night shift work can be associated with the higher risk of metabolic syndrome (MetS). However, the effect of both rotating and extended night shift work (12-hr rotating night) on MetS has not well-known. We aimed to examine and clarify the association among petrochemical workers.

METHODS

We recruited 1575 eligible workers in this study. According to shift work schedules the participants were divided into following groups: 12-hr fixed day and 12-hr rotating night. Biochemical data, including fasting blood sugar and lipid panel (TC, TG, LDL, and HDL) were determined by blood tests. Demographic data was obtained by interview at the time of blood pressure and anthropometric indices measurements. The National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) was applied to identify subjects with MetS. The Logistic regression models were used to predict risk of MetS and its components between study groups.

RESULTS

The prevalence of MetS was showed 18.4% (290/1575). We found a significant difference between study groups in the prevalence of MetS (p < 0.05). The odds ratios (ORs) and 95% confidence intervals (CIs) in the 12-hr rotating night group in comparison to the 12-hr fixed day shift group according to unadjusted and full adjusted logistic regression models were estimated 1.26 (0.96, 1.65) and 1.34 (1.01, 1.76), respectively. Among MetS components, we observed the significant higher risk in TG and HDL (P < 0.05).

CONCLUSION

This study suggests 12-hr rotating night shift as the high-risk group for MetS. More studies needed to confirm our findings.

Metabolic syndrome in shift healthcare workers

Background:

Shift work including night shifts is generally associated with chronic misalignment between the endogenous circadian timing system and behavior cycles, leading to metabolic disorders including metabolic syndrome (MS).

Objectives:

The purpose of this research was to analyze the latest developments in assessing and managing the occupational risk of MS in shift-healthcare workers (HCWs).

Methods:

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, the authors used MEDLINE/Pubmed to perform a systematic review of literature from January 2008 to December 2018.

Results:

Six studies were selected; the topics, discussed in order of frequency from highest to lowest, were: risk assessment, occurrence rates, and risk management. The main occupational determinants for MS were the cumulative shift work including night shifts and the number of nights worked per month per worker. With regard to cumulative lifetime exposure to shift work, the findings of our review suggest a dose–response relationship between increasing years of shift work history and MS in shift-HCWs.

Conclusions:

The findings suggest the need to better investigate the impact of sleep deprivation in the assessment of MS risk in shift-HCWs and clarify the role of such variables as confounders, mediators, or effect modifiers. Moreover, to date the data regarding management interventions focused on the risk of MS are inconsistent and therefore a special effort is required to detect strategic ways to minimize the likelihood of MS occurring in shift-HCWs.

Metabolic syndrome: Association between prevalence and risk at worksites

This study, conducted at major Japanese companies, aimed to determine if asymptomatic workers in workplaces with a high prevalence of metabolic syndrome have a greater risk of developing metabolic syndrome. Data were obtained from the health records of 298,145 people, from 2011 to 2015. We collected data on the participants' age, sex, physical examinations, laboratory tests, and lifestyle behaviors. To test whether the risk of metabolic syndrome in asymptomatic workers differed between groups with a higher and lower prevalence in 2011, Cox proportional hazards regression model was performed, with the covariates being controlled for. The analysis showed that the risk of metabolic syndrome among asymptomatic workers in the high-prevalence group was about 1.1-fold elevated compared to those within the low-prevalence group. As a follow-up to these results, interventions aimed at asymptomatic workers should be provided in workplaces with a high prevalence of metabolic syndrome.

Working Time Society consensus statements: Evidence-based effects of shift work on physical and mental health

Potential effects of shift work on health are probably related to the misalignment between the light-dark cycle and the human activity-rest cycle. Light exposure at night mediates these effects, including social misalignment and leads to an inversion of activity and rest, which, in turn, is linked to changes in behaviours. This article reviews the epidemiological evidence on the association between shift work and health, and possible mechanisms underlying this association. First, evidence from findings of the meta-analyses and systematic reviews published in the last 10 yr is presented. In addition, it reports the larger single-occupation studies and recent large population-based studies of the general workforce. Koch's postulates were used to evaluate the evidence related to the development of disease as a result of exposure to shift work. Finally, we discussed limitations of the multiple pathways that link shift work with specific disorders and the methodological challenges facing shift work research. We concluded that the clearest indications of shift work being the cause of a disease are given when there is a substantial body of evidence from high quality field studies showing an association and there is good evidence from laboratory studies supporting a causal explanation of the link.

Shift Work and the Risk of Cardiovascular Diseases and Metabolic Syndrome Among Jordanian Employees

Objectives

We sought to evaluate the effect of night shift working on increasing the risk of developing cardiovascular disease (CVD) using three different predictors.

Methods

One hundred and forty adult Jordanian employees were recruited in this cross-sectional study. Demographic data, anthropometric parameters, and working patterns information were documented. Metabolic syndrome (MetS) was diagnosed, and atherogenic index of the plasma (AIP) and Framingham risk score were calculated.

Results

Night shift workers had a significantly higher AIP ratio compared to daytime workers (p = 0.024). No significant association was observed between the two groups in term of 30-year Framingham risk score (p = 0.115). However, the duration of night shifts and the number of night shifts per months were found to significantly increase the 30-year Framingham risk (p = 0.000 and 0.012, respectively). Furthermore, the incidence of MetS among night shift workers was 15.9% (13/82) compared to 10.3% (6/58) among daytime workers (p = 0.484).

Conclusions

This is the first study to assess the association between night shift work and AIP as well as the 30-year Framingham risk score as predictors of CVDs. Night shift work was associated with an increase in AIP score compared to daytime work. Also, the duration of night shifts and the number of night shifts per month significantly increased the 30-year Framingham risk among night shift workers. These findings suggest an association between night shift work and the risk of CVD and atherosclerosis. Our results highlight the need for interventional strategies to diminish the risk of CVD in night shift workers.

Associations of rotational shift work and night shift status with hypertension: a systematic review and meta-analysis

BACKGROUND

The reported risks of hypertension (HTN) in rotating shift and night shift workers are controversial. The objective of this meta-analysis was to assess the association between shift work status and HTN.

METHODS

A literature search was performed using MEDLINE, EMBASE and Cochrane Database from inception through October 2016. Studies that reported odds ratios (OR) comparing the risk of HTN in shift workers were included. A prespecified subgroup analysis by rotating shift and night shift statuses were also performed. Pooled OR and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method. The protocol for this study is registered with International Prospective Register of Systematic Reviews; no. CRD42016051843.

RESULTS

Twenty-seven observational studies (nine cohort and 18 cross-sectional studies) with a total of 394 793 individuals were enrolled. The pooled ORs of HTN in shift workers in cohort and cross-sectional studies were 1.31 (95% CI, 1.07-1.60) and 1.10 (95% CI, 1.00-1.20), respectively. When meta-analysis was restricted only to cohort studies in rotating shift, the pooled OR of HTN in rotating shift workers was 1.34 (95% CI, 1.08-1.67). The data regarding night shift and HTN in cohort studies was limited. The pooled OR of HTN in night shift workers in cross-sectional studies was 1.07 (95% CI, 0.85-1.35).

CONCLUSION

Based on the findings of our meta-analysis, shiftwork status may play an important role in HTN, as there is a significant association between rotating shift work and HTN. However, there is no significant association between night shift status and risk of HTN.

Association between rotating night shift work and metabolic syndrome in Korean workers: differences between 8-hour and 12-hour rotating shift work

This study aimed to analyze the association between the shift work schedule and metabolic syndrome (MetS). This is a retrospective longitudinal study based on the 2015 health checkup data of 2,090 workers evaluated for MetS in 2010 at a general hospital in Korea. The participants were divided according to their shift work schedule into daytime, three-shift (8-h rotation), and two-shift (12-h rotation) workers. The index that indicates the association between the shift work schedule and MetS is the odds ratio (OR) calculated using multivariate logistic regression. The analysis for the entire group of workers indicated that there was positive association between two-shift rotation and MetS (OR=1.58, 95% confidence interval [CI]: 1.09, 2.29). In the analysis of rotating night-shift workers, the years of rotating night shifts, frequency of night-shift work, and sleep disturbance were added to the confounding variables, and two-shift work remained positively associated with MetS (OR=1.72, 95% CI: 1.10, 2.70). The risk of MetS differs based on the shift work schedules they engage in. Hence, structural changes to the shift work schedules are required to prevent MetS in night-shift workers.

Exploring sleep disorders in patients with chronic kidney disease

Kidney disorders have been associated with a variety of sleep-related disorders. Therefore, researchers are placing greater emphasis on finding the role of chronic kidney disease (CKD) in the development of obstructive sleep apnea and restless legs syndrome. Unfortunately, the presence of other sleep-related disorders with CKDs and non-CKDs has not been investigated with the same clinical rigor. Recent studies have revealed that myriad of sleep disorders are associated with CKDs. Furthermore, there are a few non-CKD-related disorders that are associated with sleep disorders. In this narrative review, we provide a balanced view of the spectrum of sleep disorders (as identified in International Classification of Sleep disorders-3) related to different types of renal disorders prominently including but not exclusively limited to CKD.

Association between Metabolic Syndrome and Job Rank

Background:

The occupation of the people can influence the development of metabolic syndrome.

Objective:

To determine the association between metabolic syndrome and its determinants with the job rank in workers of a large car factory in Iran.

Methods:

3989 male workers at a large car manufacturing company were invited to participate in this cross-sectional study. Demographic and anthropometric data of the participants, including age, height, weight, and abdominal circumference were measured. Blood samples were taken to measure lipid profile and blood glucose level. Metabolic syndrome was diagnosed in each participant based on ATPIII 2001 criteria. The workers were categorized based on their job rank into 3 groups of (1) office workers, (2) workers with physical exertion, and (3) workers with chemical exposure. The study characteristics, particularly the frequency of metabolic syndrome and its determinants were compared among the study groups.

Results:

The prevalence of metabolic syndrome in our study was 7.7% (95% CI 6.9 to 8.5). HDL levels were significantly lower in those who had chemical exposure (p=0.045). Diastolic blood pressure was significantly higher in those who had mechanical exertion (p=0.026). The frequency of metabolic syndrome in the office workers, workers with physical exertion, and workers with chemical exposure was 7.3%, 7.9%, and 7.8%, respectively (p=0.836).

Conclusion:

Seemingly, there is no association between metabolic syndrome and job rank.

Night work as a risk factor for future cause-specific disability pension: A prospective twin cohort study in Sweden

The objectives of the study were to investigate the associations between night work and disability pension (DP) due to all causes, cardiovascular (CVD), mental, and other diagnoses, adjusting for familial confounding. The material of the study included comprehensive survey data on 27 165 Swedish twins born in 1935-1958 that were linked with DP data for the survey period (1998-2003) to 2013. Night work was assessed as years of working nights at least every now and then, and categorized into not at all, 1-10 years and over 10 years. For statistical analyses, Cox proportional hazards regressions were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). The results of the study indicated that over 10 years duration of night work had an age- and sex-adjusted HR of 1.48 (95% CI 1.11-1.98) for DP due to CVD and 1-10 years of night work an HR of 1.28 (95% CI 1.06-1.55) for DP due to mental diagnoses, but attenuated when covariates were adjusted for. Both 1-10 years (HR 1.27, 95% CI 1.17-1.39) and >10 years of night work (HR 1.20, 95% CI 1.08-1.34) were associated with DP due to all causes and other diagnoses. These risks remained after adjusting for covariates. To conclude, even modest exposure in terms of duration of night work is a risk factor for all-cause DP, but also for DP due to mental and other diagnoses. The risk of DP due to CVD seems to be associated with longer (>10 years) periods of night work. All the associations between night work and DP seem to be influenced by various covariates.

Circadian and Metabolic Effects of Light: Implications in Weight Homeostasis and Health

Daily interactions between the hypothalamic circadian clock at the suprachiasmatic nucleus (SCN) and peripheral circadian oscillators regulate physiology and metabolism to set temporal variations in homeostatic regulation. Phase coherence of these circadian oscillators is achieved by the entrainment of the SCN to the environmental 24-h light:dark (LD) cycle, coupled through downstream neural, neuroendocrine, and autonomic outputs. The SCN coordinate activity and feeding rhythms, thus setting the timing of food intake, energy expenditure, thermogenesis, and active and basal metabolism. In this work, we will discuss evidences exploring the impact of different photic entrainment conditions on energy metabolism. The steady-state interaction between the LD cycle and the SCN is essential for health and wellbeing, as its chronic misalignment disrupts the circadian organization at different levels. For instance, in nocturnal rodents, non-24 h protocols (i.e., LD cycles of different durations, or chronic jet-lag simulations) might generate forced desynchronization of oscillators from the behavioral to the metabolic level. Even seemingly subtle photic manipulations, as the exposure to a “dim light” scotophase, might lead to similar alterations. The daily amount of light integrated by the clock (i.e., the photophase duration) strongly regulates energy metabolism in photoperiodic species. Removing LD cycles under either constant light or darkness, which are routine protocols in chronobiology, can also affect metabolism, and the same happens with disrupted LD cycles (like shiftwork of jetlag) and artificial light at night in humans. A profound knowledge of the photic and metabolic inputs to the clock, as well as its endocrine and autonomic outputs to peripheral oscillators driving energy metabolism, will help us to understand and alleviate circadian health alterations including cardiometabolic diseases, diabetes, and obesity.

Sleep duration as a mediator between an alternating day and night shift work schedule and metabolic syndrome among female hospital employees

Objectives

The main objective was to determine whether sleep duration on work shifts mediates the relationship between a current alternating day and night shift work schedule and metabolic syndrome among female hospital employees. The secondary objective was to assess whether cumulative lifetime shift work exposure was associated with metabolic syndrome.

Methods

In this cross-sectional study of 294 female hospital employees, sleep duration was measured with the ActiGraph GT3X+. Shift work status was determined through self-report. Investigation of the total, direct and indirect effects between shift work, sleep duration on work shifts and metabolic syndrome was conducted using regression path analysis. Logistic regression was used to determine the association between cumulative shift work exposure and metabolic syndrome.

Results

Shift work is strongly associated with metabolic syndrome (ORTotal=2.72, 95% CI 1.38 to 5.36), and the relationship is attenuated when work shift sleep duration is added to the model (ORDirect=1.18, 95% CI 0.49 to 2.89). Sleep duration is an important intermediate between shift work and metabolic syndrome (ORIndirect=2.25, 95% CI 1.27 to 4.26). Cumulative shift work exposure is not associated with metabolic syndrome in this population.

Conclusions

Sleep duration mediates the association between a current alternating day–night shift work pattern and metabolic syndrome.

Adverse metabolic and mental health outcomes associated with shiftwork in a population-based study of 277,168 workers in UK biobank<sup/>

BACKGROUND

Reported associations between shiftwork and health have largely been based on occupation-specific, or single sex studies that might not be generalizable to the entire working population. The objective of this study was to investigate whether shiftwork was independently associated with obesity, diabetes, poor sleep, and well-being in a large, UK general population cohort.

METHODS

Participants of the UK Biobank study who were employed at the time of assessment were included. Exposure variables were self-reported shiftwork (any shiftwork and night shiftwork); and outcomes were objectively measured obesity, inflammation and physical activity and self-reported lifestyle, sleep and well-being variables, including mental health.

RESULTS

Shiftwork was reported by 17% of the 277,168 employed participants. Shiftworkers were more likely to be male, socioeconomically deprived and smokers, and to have higher levels of physical activity. Univariately, and following adjustment for lifestyle and work-related confounders, shiftworkers were more likely to be obese, depressed, to report disturbed sleep, and to have neurotic traits.

CONCLUSIONS

Shiftwork was independently associated with multiple indicators of poor health and wellbeing, despite higher physical activity, and even in shiftworkers that did not work nights. Shiftwork is an emerging social factor that contributes to disease in the urban environment across the working population. Key messages Studies have linked shiftwork to obesity and diabetes in nurses and industry workers, but little is known about the implications of shiftwork for the general workforce In this large cross sectional study of UK workers, shiftwork was associated with obesity, depression and sleep disturbance, despite higher levels of physical activity. Shiftwork was associated with multiple indicators of compromised health and wellbeing and were more likely to report neurotic traits and evening preference.

Morning Diastolic Blood Pressure May Be Independently Associated With Severity of Obstructive Sleep Apnea in Non-Hypertensive Patients: A Cross-Sectional Study

STUDY OBJECTIVES

The aim of the study is to verify a possible association between arterial blood pressure and obstructive sleep apnea (OSA) severity in a group of non-hypertensive patients.

METHODS

This is a retrospective study of 1,171 consecutive patients referred to the sleep laboratory with complaints suggestive of OSA who underwent standard diagnostic polysomnography. In total, 454 patients with no History of arterial hypertension nor had received any such treatment were selected from this group.

RESULTS

Patients with severe OSA (apnea-hypopnea index [AHI] ≥ 30 events/h) presented with higher diastolic blood pressure (DBP) in the morning than healthy subjects (AHI < 5 events/h) or those suffering from mild (15 < AHI ≥ 5 events/h) or moderate OSA (30 < AHI ≥ 15 events/h): 86.2 ± 11.3 versus 79.2 ± 8.5, 80.3 ± 10.2 and 81.4 ± 9.6 mmHg, P < .01, respectively. In a linear regression model, a rise in morning DBP was predicted by AHI (ß = 0.14, P < .001) and body mass index (BMI) (ß = 0.22, P < .01), but not by age (ß = 0.01, P = .92), male sex (ß = -0.06, P = .19), or smoking (ß = 0.01, P = .86). In contrast, no association existed between morning systolic blood pressure (SBP) and AHI independently of BMI, sex, age, or smoking. High blood pressure (ie, SBP ≥ 140 mmHg or DBP ≥ 90 mmHg on each of three measurements on different occasions) was predicted by age of 42 years or older, BMI of at least 29 kg/m2, and severe OSA.

CONCLUSIONS

High AHI, independent of obesity, age and sex, was associated with elevated DBP in the morning. Thus, elevated morning DBP may be one of the symptoms related to OSA that warrants specific diagnostics.

COMMENTARY

A commentary on this article appears in this issue on page 861.

Night-shift work is associated with poorer glycaemic control in patients with type 2 diabetes

The circadian system plays a role in regulating metabolism. Night-shift work, a form of circadian misalignment, is associated with increased type 2 diabetes risk. This study aimed to determine if night-shift workers with type 2 diabetes experience poorer glycaemic control than non-shift workers. Patients with type 2 diabetes (104 unemployed, 85 day workers and 60 night-shift workers) participated. Sleep duration, sleep quality, morningness-eveningness preference, depressive symptoms and dietary intake were assessed using standardized questionnaires. Haemoglobin A1c levels were measured. Night-shift workers had significantly higher haemoglobin A1c levels compared with others, while there were no differences between day workers and unemployed participants (median 7.86% versus 7.24% versus 7.09%, respectively). Additionally, night-shift workers were younger, had a higher body mass index, and consumed more daily calories than others. Among night-shift workers, there were no significant differences in haemoglobin A1c levels between those performing rotating versus non-rotating shifts (P = 0.856), or those with clockwise versus counterclockwise shift rotation (P = 0.833). After adjusting for age, body mass index, insulin use, sleep duration, morningness-eveningness preference and percentage of daily intake from carbohydrates, night-shift work, compared with day work, was associated with significantly higher haemoglobin A1c (B = 0.059, P = 0.044), while there were no differences between unemployed participants and day workers (B = 0.016, P = 0.572). In summary, night-shift work is associated with poorer glycaemic control in patients with type 2 diabetes.

Can short-wavelength depleted bright light during single simulated night shifts prevent circadian phase shifts?

In single night shifts, extending habitual wake episodes leads to sleep deprivation induced decrements of performance during the shift and re-adaptation effects the next day. We investigated whether short-wavelength depleted (=filtered) bright light (FBL) during a simulated night shift would counteract such effects. Twenty-four participants underwent a simulated night shift in dim light (DL) and in FBL. Reaction times, subjective sleepiness and salivary melatonin concentrations were assessed during both nights. Daytime sleep was recorded after both simulated night shifts. During FBL, we found no melatonin suppression compared to DL, but slightly faster reaction times in the second half of the night. Daytime sleep was not statistically different between both lighting conditions (n = 24) and there was no significant phase shift after FBL (n = 11). To conclude, our results showed positive effects from FBL during simulated single night shifts which need to be further tested with larger groups, in more applied studies and compared to standard lighting.

Shift Work Is Associated with Metabolic Syndrome in Young Female Korean Workers

Background

Shift work is associated with health problems, including metabolic syndrome. This study investigated the association between shift work and metabolic syndrome in young workers.

Methods

A total of 3,317 subjects aged 20–40 years enrolled in the 2011–2012 Korean National Health and Nutrition Examination Survey were divided into shift and day workers. We conducted a cross-sectional study and calculated odds ratios using multivariate logistic regression analysis in order to examine the association between shift work and metabolic syndrome.

Results

The prevalence of metabolic syndrome was 14.3% and 7.1% among male and female shift workers, respectively. After adjusting for confounding factors, shift work was associated with metabolic syndrome in female workers (odds ratio, 2.53; 95% confidence interval, 1.12 to 5.70).

Conclusion

Shift work was associated with metabolic syndrome in young women. Timely efforts are necessary to manage metabolic syndrome in the workplace.

Metabolic disturbances due to a high-fat diet in a non-insulin-resistant animal model

Objective:

Shift workers have metabolic changes more often than day workers. It is also known that night workers prefer foods high in saturated fat. Such data suggest that shift workers are prone to cardiovascular disease. Therefore, the objective of this study was to propose an animal model to test the effect of high-fat diet (HFD) based on shift workers' diet.

Methods:

This is an experimental study with 20 Wistar rats. Ten rats were allocated to the control group (CG) and were fed standard diet. Ten rats were allocated to the experimental group (EG) and were fed HFD (45% fat). Serum triglycerides (TG), glucose and high-density lipoprotein-cholesterol (HDL-cho) were measured 5, 10 and 15 weeks after the beginning of the study. The amount of visceral adipose tissue (VAT) was determined. Body weight was assessed weekly, and food and water intake were measured daily. Student's t-test was used for independent samples, and P<0.05 was considered significant.

Results:

After 15 weeks of intervention, the EG showed increased serum levels of TG (P=0.001) and glucose (P<0.001) and decreased HDL-cho (P<0.001) when compared with the CG. The EG showed increased VAT (P=0.005) and liver weight (P=0.01). Food intake and water intake were higher in the CG (P<0.001 and P<0.001, respectively), whereas energy intake showed no difference (P=0.48). No difference was found in the weight of adrenal glands (P=0.07) and body weight (P=0.63).

Conclusions:

The experimental diet was effective to show changes in the serum levels of glucose, TG and HDL-cho and visceral fat in spite of no change in body weight in 15 weeks.

Role of Physical Exercise, Education and Work Related Measures with the Longevity of Work in Older Population in United States

Growth of older population in United States (US) raises concerns for evaluation of health indices that could sustain their workability. This study aimed to characterize the association of health practices used by older working population and measures of quality and duration of their work. Forty (40) non-treatment seeking healthy working individuals residing within United States within 22 - 75 years of age were included in this study. Data were collected from the Customized Employee Biographical Questionnaire (EBQ) and Occupational Health Surveillance Questionnaire (OHRQ) by age groups as 22 - 31, 32 - 41, 42 - 51, 52 - 61 and 62+ and statistically analyzed. Length of working (LOW) showed close association with the duration of physical exercise (DPE) at adjusted R² = 0.295 and type of work (TOW) at adjusted R² = 0.598; and Education in the 62+ (oldest) age group. However such relationship was not observed in the 52 - 61 years age group even when DPE and Education were not significantly different from the 62+ group. In the 42 - 51 age group, significant correlation of LOW with DPE and TOW was found. Duration of physical activity could be an important factor associated with the duration of work in the oldest group. Type of work could be significant modifier in determining the length of working in older age-groups. Predecessor elderly groups might need to incorporate some of the measures that were significant in the oldest group, to improve their expectations to work longer. Larger studies could identify and capture various other measures that could be important both for the regional and national US perspective.

The Relationship Between Shift Work and Metabolic Risk Factors: A Systematic Review of Longitudinal Studies

CONTEXT

Although the metabolic health effects of shift work have been extensively studied, a systematic synthesis of the available research is lacking. This review aimed to systematically summarize the available evidence of longitudinal studies linking shift work with metabolic risk factors.

EVIDENCE ACQUISITION

A systematic literature search was performed in 2015. Studies were included if (1) they had a longitudinal design; (2) shift work was studied as the exposure; and (3) the outcome involved a metabolic risk factor, including anthropometric, blood glucose, blood lipid, or blood pressure measures.

EVIDENCE SYNTHESIS

Eligible studies were assessed for their methodologic quality in 2015. A best-evidence synthesis was used to draw conclusions per outcome. Thirty-nine articles describing 22 studies were included. Strong evidence was found for a relation between shift work and increased body weight/BMI, risk for overweight, and impaired glucose tolerance. For the remaining outcomes, there was insufficient evidence.

CONCLUSIONS

Shift work seems to be associated with body weight gain, risk for overweight, and impaired glucose tolerance. Overall, lack of high-methodologic quality studies and inconsistency in findings led to insufficient evidence in assessing the relation between shift work and other metabolic risk factors. To strengthen the evidence, more high-quality longitudinal studies that provide more information on the shift work schedule (e.g., frequency of night shifts, duration in years) are needed. Further, research to the (mediating) role of lifestyle behaviors in the health effects of shift work is recommended, as this may offer potential for preventive strategies.

The Relationship of Metabolic Syndrome with Stress, Coronary Heart Disease and Pulmonary Function--An Occupational Cohort-Based Study

BACKGROUND AND AIMS

Higher levels of stress impact the prevalence of metabolic syndrome (MetS) and coronary heart disease. The association between MetS, impaired pulmonary function and low level of physical activity is still pending assessment in the subjects exposed to stress. The study aimed to examine whether higher levels of stress might be related to MetS and the plaque presence, as well as whether MetS might affect pulmonary function.

DESIGN AND METHODS

The study embraced 235 police officers (mean age 40.97 years) from the south of Poland. The anthropometrics and biochemical variables were measured; MetS was diagnosed using the International Diabetes Federation criteria. Computed tomography coronary angiography of coronary arteries, exercise ECG, measurements of brachial flow-mediated dilation, and carotid artery intima-media thickness were completed. In order to measure the self-perception of stress, 10-item Perceived Stress Scale (PSS-10) was applied. Pulmonary function and physical activity levels were also addressed. Multivariate logistic regression analyses were applied to determine the relationships between: 1/ incidence of coronary plaque and MetS per se, MetS components and the number of classical cardiovascular risk factors, 2/ perceived stress and MetS, 3/ MetS and pulmonary function parameters.

RESULTS

Coronary artery atherosclerosis was less associated with MetS (OR = 2.62, 95%CI 1.24-5.52; p = 0.011) than with a co-existence of classical cardiovascular risk factors (OR = 5.67, 95% CI 1.07-29.85, p = 0.03; for 3 risk factors and OR = 9.05; 95% CI 1.24-66.23, p = 0.02; for 6 risk factors, respectively). Perceived stress increased MetS prevalence (OR = 1.07, 95% CI 1.03-1.13; p = 0.03), and impacted coronary plaque prevalence (OR = 1.05, 95% CI 1.001-1.10; p = 0.04). Leisure-time physical activity reduced the chances of developing MetS (OR = 0.98 95% CI 0.96-0.99; p = 0.02). MetS subjects had significantly lower values of certain pulmonary function parameters.

CONCLUSIONS

Exposure to job-specific stress among police officers increased the prevalence of MetS and impacted coronary plaque presence. MetS subjects had worse pulmonary function parameters. Early-stage, comprehensive therapeutic intervention may reduce overall risk of cardiovascular events and prevent pulmonary function impairment in this specific occupational population.