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Shift Work and the Relationship with Metabolic Syndrome in Chinese Aged Workers
PLOS ONE
Abstract and Figures
Shift work is indicated to be associated with adverse metabolic disorders. However, potential effects of shift work on metabolic syndrome (MetS) and its components have not been well established.
In total, 26,382 workers from Dongfeng-Tongji Cohort were included in this study. Information on shift work history was gathered through questionnaires and metabolic traits were measured. Logistic regression models were used to calculate the odds ratio (OR) and 95% confidence interval (CI) for long-term shift work related with MetS and each component, respectively. Further stratification analysis was performed to detect the differences on MetS between female and male shift workers.
Long-term shift work was associated with MetS without adjusting for any confounders. Compared with the group of non-shift work, the multivariate-adjusted ORs (95%CI) of MetS associated with 1-10, 11-20, and ≥20y of shift work were 1.05 (0.95-1.16), 1.14 (1.03-1.26), 1.16 (1.01-1.31), respectively. In female workers, we found a dose-response relationship that every 10 years increase in shift work was associated with a 10% (95% CI: 1%-20%) elevated OR of MetS, while no significant dose-response trend was found among male workers. Furthermore, shift work duration was significantly associated with ORs of high blood pressure (1.07, 1.01-1.13), long waist circumference (1.10, 1.01-1.20) and high glucose levels (1.09, 1.04-1.15). No significant association was observed between shift work and low HDL cholesterol) and raised triglyceride levels.
Long-term shift work was associated with metabolic syndrome and the association might differ by gender in retired workers. Applicable intervention strategies are needed for prevention of metabolic disorders for shift workers.
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... Se han realizado investigaciones que relacionan a los trabajadores por turnos y sus afecciones en el ritmo de sueño y descanso (12), (13) que modifican sus ritmos circadianos, y estos a su vez desencadenan en problemas de alteración de glucosa, resistencia a la insulina, aumento de peso, aumento de apetito, obesidad (14), (15), (16), (17). Al ser la resistencia a la insulina un factor de riesgo para el desarrollo de diabetes tipo 2 (18), es necesario analizar los agentes probablemente desencadenantes, como es la interrupción del ciclo sueño, y de esa manera buscar medidas preventivas en todos los individuos que están expuestos. ...
... En el estudio reciente de Ravibabu y col (26) se pudo valorar la resistencia a la insulina en tres grupos diferentes que incluyen a los trabajadores estrictamente diurnos, rotativos y nocturnos, haciéndolo más completo al incluir dos grupos que conforman los trabajadores por turnos para poder identificar si hay diferencias entre ellos o este factor insulinico solo se ve afectado en el grupo nocturno como ya se ha evidenciado en todas las investigaciones anteriores, los resultados arrojaron que el índice HOMAIR fue mayor proporcionalmente en el turno nocturno, seguido del turno rotativo aunque no se encontraron diferencias significativas al comparar sólo el turno nocturno con el turno rotativo o trabajadores diurnos, además también se valoró parámetros del síndrome metabólico encontrando un mayor porcentaje de igual forma en el trabajador de la noche, este resultado en el síndrome metabólico se ha demostrado también en varias investigaciones anteriores en los que se ve clara su clara asociación (15), (17). ...
El ciclo normal del sueño controlado por los ritmos circadianos del reloj central tiene una íntima relación con el correcto funcionamiento de los sistemas del cuerpo, uno de ellos es la regulación del metabolismo, hay evidencia que la interrupción del sueño como es el caso de los trabajadores por turnos afecta el metabolismo de la glucosa, de lípidos y la resistencia a la insulina siendo un factor de riesgo de desarrollar diabetes. El objetivo fue asociar las alteraciones del ciclo sueño/vigilia que ocurren en trabajadores por turnos con el aumento de la resistencia a la insulina en personas adultas. Se utilizaron bases de datos electrónicas como Pubmed, Scielo, Science Direct, Scopus y Web of Science; libros electrónicos y la Wiley Online Library; escogiendo aquellos realizados entre los años 2011 y 2021, en idiomas inglés y español, y solo en humanos. De un total de 222 artículos, según los criterios de elegibilidad, se escogieron ocho transversales y dos cruzados aleatorizados. Se encontró una evidencia media que asocia las alteraciones del sueño que ocurren en los trabajadores por turnos en mayor proporción los de turno nocturno con disminución de la sensibilidad y aumento de la resistencia a la insulina.
... In this industrial era, more women are working since the opportunity and the economic demand for family income are getting higher. Previous studies in other countries show that more females than males work in the industrial sectors 3,4 . In Indonesia, West Java Province is the second province that has a high number of female workers 5 . ...
... The workload might cause reproductive health problems among the female workers 3 . Furthermore, the other study found work shift increased the risk to have hypertension and high blood sugar 4 Hypertension may lead to premature birth 11 . Therefore, it is important to know the health profile of female workers, so that the reproductive health risk among them could be identified to prevent morbidity and mortality among mother and child. ...
Background: Maternal and child morbidity and mortality remains problems in Indonesia. Based on the life cycle approach, the improvement should be done before the pregnancy which targeted to reproductive age women. One group that need attention is industrial female workers. It is crucial to know their health profile and reproductive health risk they may have. Objective: to describe the health profile of industrial female workers and their reproductive health risk in Bekasi District, Indonesia Method: We used cross sectional study design and involved 386 industrial female workers who live in Bekasi Disrict as respondents. The data collection was carried out during November 2021. We interviewed the respondents using questionnaire and measured their body mass index, total body fat, visceral fat, blood pressure, and random blood sugar. We analysed the data using univariate analysis. Result:. The respondent who categorized as obese based on body mass index (52.8%), total body fat (72%), visceral fat (9.8%). 11.9% respondents were suspected to hypertension, while 26.9% were suspected to hypertension according to diastole blood pressure measurement. The distribution of respondents who had potential risk to get diabetes was 2.3%. The anemia status of respondents was 10.4%. The result analysis shows that 88.3 % of respondents had risk to experience during pregnancy, delivery, and risk to have stunted baby because their health profile. Conclusion: The health profile of industrial female workers in this study indicated they have risk to obesity, diabetes mellitus and hypertension. This health profile placed them to the reproductive health risk, especially related to pregnancy and delivery. They also have risk to have stunted baby if they experience pregnancy. Keywords:, Female workers, industrial, health profile, reproductive health risk, Indonesia
... These results replicate findings from previous studies that showed an association between nightshift work and higher triglycerides levels (Ghiasvand et al., 2006;De Bacquer et al., 2009). However, some other studies do not confirm this association between nightshift work and triglyceride levels (Esquirol et al., 2011;Guo et al., 2015;Proper et al., 2016;Huang et al., 2021), which might be partly explained by the different age range of these study populations. We mainly find an effect in the (younger) recently started nightshift workers, while, for example, a large high quality cohort study in an older population of retired workers did not observe an effect in triglyceride levels (Guo et al., 2015). ...
... However, some other studies do not confirm this association between nightshift work and triglyceride levels (Esquirol et al., 2011;Guo et al., 2015;Proper et al., 2016;Huang et al., 2021), which might be partly explained by the different age range of these study populations. We mainly find an effect in the (younger) recently started nightshift workers, while, for example, a large high quality cohort study in an older population of retired workers did not observe an effect in triglyceride levels (Guo et al., 2015). Recently started nightshift workers had a mean age of 30 (SD 10), compared to a mean age 42 (SD 11) for the more experienced nightshift workers, which might have had an impact on differences in dietary intake and patterns between those groups. ...
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.
... Shift work was interpreted as individuals employed on work schedules that deviated from the standard daytime working hours, typically from 9:00 AM to 17:00 PM, for a period exceeding three months (Guo et al. 2015). The classification of physical labor intensity is mainly based on the level of energy consumption at work. ...
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.
... The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/antiox12040959/s1. Table S1: The relation between shift work and MetS -epidemiological studies [158][159][160][161][162][163][164][165][166][167][168]. ...
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.
... Algunos estudios han descrito que la edad y la antigüedad pueden ser factores importantes para el desarrollo del síndrome metabólico y sus componentes (Guo, 2013;Guo et al., 2015). Los participantes de esta investigación tuvieron una mediana de edad que no sobrepasa los 40 años, siendo aún más jóvenes los trabajadores que no rotan turnos. ...
Debido al aumento en la demanda de producción en las empresas alrededor del mundo, así como la posibilidad de reducir los costos de manufactura, cada vez más personas trabajan con rotación de turnos. En diversas investigaciones el trabajo por turnos ha sido relacionado con repercusiones negativas para la salud de las personas que laboran bajo este sistema, tales como hipertensión, diabetes, obesidad y dislipidemias, que son componentes del síndrome metabólico. En una investigación desarrollada en una empresa de manufactura de autos, en la que existen dos calendarios: rotación de turnos (obreros) y no rotación de turnos (administrativos), se indentificó mediante el análisis de tres evaluaciones médicas que se hicieron a los trabajadores en los años 2015, 2016 y 2017, que los niveles de colesterol total, triglicéridos, índice de masa corporal e índice cintura cadera son más altos y el colesterol HDL es más bajo en los trabajadores por turno que en los que no laboran de esta manera. Aunque no se pudo comprobar una relación entre el trabajo por turnos y el síndrome metabólico es importante saber que trabajar rotando turnos es un factor que puede favorecer modificaciones hormonales y metabólicas que ocasionan problemas de salud.
... Other studies on the association between shift work and Metabolic syndrome do not always show a positive association between the two factors [18][19][20][21][22][23]. The discrepancy in these results is likely due to cross-sectional design and non-objective data. ...
(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.
... Therefore, night shift workers, such as emergency room physicians, have a significant liability to develop poor sleep quality. A fair number of studies have focused on the effects of shift work on the general health, and have found a link between shift work and cardiovascular diseases [6][7][8][9][10][11][12] , diabetes mellitus type 2 [13][14][15][16][17] , breast canser 21 , metabolic syndrome [22][23] , memory loss 24 and obesity [25][26] . In contrast, fewer studies have addressed the relation between shift work and its effect on sleep quality and it is negative consequences on sleep patterns and mood. ...
Hypercholesterolemia (high cholesterol) is an important risk factor for the development of cardiovascular disease (CVD). Shift work is now considered as one of the possible factors that could have an effect on lipid profile. The aim of this study was to determine the association of shift work with hypercholesterolemia among nurses. This cross‐sectional and descriptive-analytical study was conducted on nurses who worked in three hospitals. The sample size was 120 participants and divided into 60 shift workers and 60 day workers (nonshift workers). Demographic data, medical and occupational history were collected through a checklist. Data were analyzed by Mann–Whitney U, chi-square, and logistic regression analysis using SPSS version 22. There was statistically significant difference between prevalence of hypercholesterolemia and shift work. Also, a small percentage (8.33%) had low levels of HDL (high-density lipoprotein) in shift workers and 5% in day workers. On the other hand, there was no significant difference between HDL and shift work. The findings of this study showed that shift work is a risk factor for Hypercholesterolemia and increased duration of shift work was associated with higher risk of hypercholesterolemia in shift working nurses. Due to the indispensable of shift work in the nursing profession, it is essential to teach courses to promote healthy work environments and conduct periodical checkup to help nurses decrease their occupational problems.
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.
Objectives We examined the association of night shift work history and age when night shift work was performed with cancer and cardiovascular disease risk factors among 54 724 women in the Nurses’ Health Study (NHS) II.
Methods We calculated age-adjusted and socioeconomic status-adjusted means and percentages for cancer and cardiovascular risk factors in 2009 across categories of night shift work history. We used multivariable-adjusted logistic regression to estimate odds ratios (ORs) and 95% CIs for key risk factors among 54 724 participants (72% ever shift workers). We further examined these associations by age (20–25, 26–35, 36–45 and 46+ years) at which shift work was performed.
Results Ever night shift workers had increased odds of obesity (body mass index ≥30 kg/m2; OR=1.37, 95% CI 1.31 to 1.43); higher caffeine intake (≥131 mg/day; OR=1.16, 95% CI 1.12 to 1.22) and total calorie intake (≥1715 kcal/day; OR=1.09, 95% CI 1.04 to 1.13); current smoking (OR=1.30, 95% CI 1.19 to 1.42); and shorter sleep durations (≤7 h of sleep/day; OR=1.19, 95% CI 1.15 to 1.24) compared to never night shift workers. These estimates varied depending on age at which night work was performed, with a suggestion that night shift work before age 25 was associated with fewer risk factors compared to night shift work at older ages.
Conclusions Our results indicate that night shift work may contribute to an adverse chronic disease risk profile, and that risk factors may vary depending on the age at which night shift work was performed.
This study aimed to determine identify any association between shift work and the metabolic syndrome by comparing the prevalence rates of the metabolic syndrome in shift work groups and daytime work groups for female workers.
Based on data from health examinations carried out from April to December of 2012, we selected as our subjects 254 female workers from the Daegu area Dyeing Industrial Complex. We diagnosed the metabolic syndrome using the examination results, and information about age, whether or not they did shift work, job type, smoking habits, drinking habits, exercise habits, and past medical history was collected through self-administered questionnaire surveys and face-to-face interviews. The variables found in a univariate analysis to be significant in the occurrence of the metabolic syndrome - age, drinking habits, exercise habits, and shift work - were included in a logistic regression analysis of the risk of the metabolic syndrome for female workers.
The prevalence rates of the metabolic syndrome for the total group of study subjects was 11.8%, for daytime workers was 2.8%, and for shift workers was 15.3%. A logistic regression analysis of the odds of the metabolic syndrome for female workers was conducted that included factors associated with the occurrence of the metabolic syndrome: age, drinking habits, exercise habits, and shift work. The results revealed that the odds ratio of the metabolic syndrome in the shift work group, 6.30 (95% CI 1.24-32.15), was significantly higher when compared with the daytime work group.
Shift work appears to have an association with the metabolic syndrome in female workers. Accordingly, we believe that the attention of government agencies and business owners is needed together with the individual practice of health behaviors to manage the metabolic syndrome for the prevention of cardiovascular disease in female shift workers.
Background
Not all the people with metabolic syndrome (MS) have abdominal obesity (AO). The study aimed to investigate gender differences in the prevalence and development of MS in Chinese population with abdominal obesity, which has rarely been reported.
Methods
Data were obtained from the 2007-08 China National Diabetes and Metabolic Disorders Study, and participants were divided into two samples for analysis. Sample 1 consisted of 19,046 people with abdominal obesity, while sample 2 included 2,124 people meeting pre-specified requirements. Survival analysis was used to analyze the development of MS.
Results
The age-standardized prevalence of MS in Chinese population with AO was 49.5%. The prevalence in males (73.7%) was significantly higher than that in females (36.9%). Males had significantly higher proportions of combinations of three or four MS components than females (36.4% vs. 30.2% and 18.4% vs. 5%, respectively). MS developed quick at first and became slow down later. Half of the participants with AO developed to MS after 3.9 years (95% CI: 3.7–4.1) from the initial metabolic abnormal component, whereas 75% developed to MS after 7.7 years (95% CI: 7.5–7.9).
Conclusion
Compared with females, Chinese males with AO should receive more attention because of their higher prevalence of MS and its components, more complex and risky combinations of abnormal components, and faster development of MS.
The aim of the present study was to assess the association between metabolic syndrome (MS) and coronary artery disease (CAD) complexity assessed by SYNTAX score (SS) and severity in non-diabetic patients with stable CAD whom underwent coronary angiography and to evaluate whether the MS defined by different definitions including International Diabetes Federation (IDF) and (American Heart Association/National Heart Lung Blood Institute) AHA/NHLBI guidelines similarly correlated with SS.
The present study is cross sectional and observational with prospective inclusion of 248 consecutive patients (157 male) who underwent coronary angiography due to stable coronary artery disease.
The prevalence of MS was 54.4% according to IDF definition and 50.4% according to AHA/NHLBI definition. MS score according to IDF definitions (r=0.446, p<0.001), MS score according to AHA/NHLBI definitions (r=0.341, p<0.001) were moderately correlated with SS. In Fisher r to z transformation test the correlations of the presence of MS according to IDF and AHA/NHLBI definitions with SS was not statistically significant (p=0.168, z=-1.38). The systolic blood pressure (p<0.001, B=0.354, CI95%=-0.308-0.228), diastolic blood pressure (p=0.006, B=-0.194, CI95%=-0.333- -0.056), age (p=0.014, B=0.147, CI95%=0.029-0.264), left ventricular ejection fraction (p=0.031, B=-0.150, CI95%=-0.286- -0.014), waist/hip circumference (p<0.001, B=45.713, CI95%=23.235-68.1919) and log10 high density lipoprotein (p<0.001, B=-22.209, CI95%=-33.298- -11.119) were the independent predictors of SS in linear regression analysis.
Metabolic syndrome is associated with the presence and complexity of CAD. Besides the presence of discrepancy about the limits of waist circumference, both IDF and AHA/NHLBI criteria were similarly correlated with CAD complexity.
Metabolic syndrome is considered as mainly caused by a deleterious lifestyle (sedentarity and diet). That smoking contributes to metabolic syndrome had been suggested by several small studies and a meta-analysis. The interesting study by Slagter et al. published in BMC Medicine is the first very large study confirming this association in both genders, in all classes of body mass index, and in a dose-related manner. Surprisingly, smoking is even associated with increased abdominal fat. Rather than a direct causal effect of smoking, the reason for these associations is most probably the frequent presence of other lifestyle components in smokers. For example, physical inactivity and alcohol drinking are known to be more often present in smokers and could completely explain the observations of the Slagter et al. study. Unfortunately, these factors, already not properly checked in the first studies, were not assessed at all in the present one. However, as it is still on-going, we hope that other lifestyle factors will be included in future publications.
Please see related research: http://www.biomedcentral.com/1741-7015/11/195.
Young to middle-aged women usually have notably lower rates of cardiovascular disease (CVD) than their male counterparts, but African American women lack this advantage. Their elevated CVD may be influenced by sex differences in associations between depressed mood and CVD risk factors. This cross-sectional study examined whether relations between scores on the Center for Epidemiologic Studies-Depression (CES-D) scale and a spectrum of CVD risk factors varied by sex among African Americans (n = 1076; ages 30-64) from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study. Sex-stratified multiple regressions and logistic regressions were conducted. Among women, CES-D scores correlated positively with systolic blood pressure and waist-to-hip ratio (P's < .05), but inversely with high-density lipoprotein cholesterol (HDL-C) (P < .01). Women had twice the odds for metabolic syndrome if CES-D scores ≥16 and had a ≥14% increase in odds of hypertension, abdominal obesity, and low HDL-C with each 5-unit increase in CES-D scores. Among men, CES-D scores correlated positively with high-sensitivity C-reactive protein (P < .05), and odds of hypertension increased by 21% with each 5-unit increase in CES-D scores. Depressive symptoms may promote premature CVD risk in African Americans, at least in part, via CVD risk factors and prevalent metabolic syndrome, particularly in African American women.
In this narrative review, we examined what level of research evidence is available that shift workers’ sleep–wake disturbances can be minimized through ergonomic shift scheduling. We classified the pertinent studies conducted on real shift workers in field conditions by the type of shift system and study design (ie, whether the shift systems were modified or not – “treatment” versus “no treatment”). The results of the observational studies in which no changes to the shift system were made (ie, no treatment) showed that, irrespective of the shift system, night and early-morning shifts and quick returns are associated with short sleep and increases in sleepiness. The same is true for very long shifts (>16 hours) and extremely long weekly working hours (>55 hours). For all categories of shift systems, there was a lack of controlled intervention studies, limiting the possibility to provide solution-focused recommendations for shift scheduling. Most of the controlled intervention studies had been conducted on workers under regular 3-shift systems. These studies suggested that a change from slowly backward-rotating shifts to rapidly forward-rotating shifts is advantageous for alertness and, to some degree, sleep. We also found that a change from an 8- to 12-hour shift system does not necessarily result in impairments in the sleep–wake pattern. The level of research evidence was affected by many of the studies’ frequent methodological limitations in measuring sleep and sleepiness. In all, to have reliable and solution-focused recommendations for shift scheduling, methodologically sound controlled intervention studies are required in different categories of shift systems.
Objectives This study aims to quantitatively summarise the association between night shift work and the risk of metabolic syndrome (MetS).
Method We systematically searched all observational studies published in English on Pubmed and Embase from 1971 to 2013. We extracted effect measures (relative risk, RR; or odd ratio, OR) with 95% confidence interval (CI) from individual studies to generate pooled results using meta-analysis approach. Pooled RR was calculated using random- or fixed effect model. Downs and Black scale was applied to assess the methodological quality of included studies.
Results A total of 13 studies were included in the meta-analysis. The pooled adjusted RR for the association between “ever exposed to night shift work” and MetS risk was 1.57 (95% CI = 1.24–1.98, pheterogeneity = 0.001). Further stratification analysis for gender, MetS definition and study population demonstrated similar trends. The sensitivity analysis confirmed the stability of the results and no publication bias was detected.
Conclusions The present meta-analysis suggests that night shift work is significantly associated with the risk of MetS, showing a positive dose-response relationship with the intensity of night shifts. Large-scale well-design prospective studies are required to further investigate the association, especially in Asia countries.[National Natural Science Foundation of China (Project number 81273172 and 81372964), Shelly@cuhk.edu.hk (Lap Ah Tse)]
To investigate the influence of sex and age on the relationship between sleep duration and metabolic syndrome in a nationally representative population.
We used data from the Korea National Health and Nutrition Examination Survey (2001-2010) and enrolled 24,511 participants aged 20-79 years. Sleep duration was categorized into five groups: ≤5, 6, 7 (referent), 8, and ≥9h/day. Age was categorized into three groups: younger (20-39y), middle-aged (40-59y), and older (60-79y). The association between sleep duration and metabolic syndrome was assessed in the total, separately in men and women, then in six groups based on sex and age.
The prevalence of metabolic syndrome by sleep category demonstrated a U-shaped pattern in the total population. However, after adjusting for age, education, occupation, exercise, smoking, alcohol, and body mass index, the prevalence of metabolic syndrome increased in long sleepers (OR 1.31; 95% CI 1.14-1.51) but not in short sleepers (OR 1.00; 95% CI 0.89-1.11). The relationship between sleep duration and metabolic syndrome varied by sex and age-long sleep (≥9h/day) was positively associated with metabolic syndrome only in younger (OR 2.13; 95% CI 1.38-3.28) and middle-aged (OR 1.63; 95% CI 1.21-2.21) women. Short sleep (≤5h/day) was not associated with metabolic syndrome in any sex and age groups. However, extremely short sleep (≤4h/day) was associated with metabolic syndrome in middle-aged men (OR 1.76, 95% CI 1.05-2.96).
These data suggest that sex and age significantly modify the relationship between sleep duration and metabolic syndrome.