Rotational Shift Workers Research Articles

Association between shift work and obesity in a large sample of Iranian steel industry workers.

Obesity is associated with several chronic diseases, and previous research suggests that shift work could be associated with the risk of overweight and obesity, but the results remain inconclusive. Furthermore, only a few studies report related findings for industrial workforce with high job-related stress. The aim of this cross-sectional study was to see if such association exists in a large sample of 3063 industrial workers in a developing country. The sample was selected among 16,000 steel company workers through multistage cluster sampling. We took anthropometric measurements, including body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR). Information about potential confounders was collected with a self-administered questionnaire. The association between shift work and both general and abdominal obesity was established with multinomial and binary logistic regression analysis. The study sample consisted of 1683 (54.9 %) rotational shift workers and 1380 (45.1 %) day workers. Shift work was significantly associated with higher risk of overweight after adjusting for the impacts of potential confounders (OR=1.2; 95 % CI:1.04-1.4) but not with abdominal obesity. This study established that shift work was an independent risk factor for overweight in industrial shift workers. Modification of working schedules is recommended, particularly for prolonged, continuous shift work.

NOCTURNIN Gene Diurnal Variation in Healthy Volunteers and Expression Levels in Shift Workers.

Objective The NOCTURNIN gene links nutrient absorption and metabolism to the circadian clock. Shift workers are at a heightened risk of overweight and of developing obesity and metabolic syndrome. This study investigates the diurnal variation of NOCTURNIN in healthy volunteers and its expression levels in rotational shift and daytime workers. Methods NOCTURNIN expression levels were evaluated in peripheral blood lymphocytes from 15 healthy volunteers at 4-hour intervals for 24 h. Metabolic parameters and NOCTURNIN expression were measured in workers engaged in shift and daytime work. Results In the group of volunteers NOCTURNIN expression showed diurnal variation, with a peak at 8:00 AM. NOCTURNIN expression was higher in shift workers than in daytime workers. Multivariate analysis confirmed the role of shift work as an independent factor affecting NOCTURNIN expression. Notably, its level correlated directly with body mass index and inversely with total energy expenditure. Conclusions Measuring NOCTURNIN expression levels in human peripheral blood lymphocytes can improve investigations on the relationship between changes in circadian rhythm and metabolic disorders. Shift workers show higher NOCTURNIN levels than daytime workers.

Dietary patterns in relation to inflammation in shift workers

IntroductionRotational shift work has a considerable effect on immune function and cause inflammation. In addition, it may lead to unhealthy dietary intake. No earlier study has examined the association between...

Altered Regional Cerebral Blood Flow Associated with Mood and Sleep in Shift Workers: Cerebral Perfusion Magnetic Resonance Imaging Study.

Background and PurposeShift work disrupts the body's circadian rhythms and increases the risk of health problems. Despite evidence of neuropsychological disturbances in shift workers (SW), the brain functional status as measured by brain perfusion in chronic shift work has not been evaluated previously. We investigated the regional cerebral blood flow (rCBF) in SW using perfusion MRI (pMRI) and evaluated the relationships between altered rCBF and sleep, mood, psychometric measures, and quality of life.MethodsFifteen rotational SW and 15 day workers (DW) were enrolled. The participants were all female nurses working at a university-affiliated hospital. During 2 weeks of actigraphy they underwent pMRI scanning and psychometric testing on the last day immediately after working. Demographic characteristics, insomnia, daytime sleepiness, and mood were compared between the groups.ResultsThe participants were aged 35.3±2.9 years (mean±SD) and had been performing their current work for more than 2 years. The demographic characteristics did not differ between SW and DW, but the levels of insomnia, anxiety, depression, and hyperactivity-restlessness in psychometric measures were higher in SW than in DW. Cerebral perfusion in SW was significantly decreased in the cuneus, fusiform/parahippocampal gyri, and cerebellum of the right hemisphere, while it was increased in the inferior occipital gyrus of the left hemisphere. Perfusion changes in SW were significantly correlated with depression and insomnia severity. The onset and duration irregularity of sleep among SW were related to insomnia, mood, hyperactivity/ restlessness, and quality of life.ConclusionsSW experience considerably more insomnia and mood disturbances than do DW, and this is significantly related to perfusion changes in multiple brain areas.

Association of obesity in shift workers with the minor allele of a single-nucleotide polymorphism (rs4851377) in the largest circadian clock gene (NPAS2)

ABSTRACTA growing body of evidence has hinted at the involvement of the largest gene of the circadian clock family, NPAS2, in the regulatory mechanisms underlying the link between metabolic diseases and circadian rhythm disruption. We tested whether one of single-nucleotide polymorphisms in NPAS2 (rs4851377) is associated with obesity and alternations of sleep times in 126 male rotational shift workers (bus drivers). We confirmed positive association of Body Mass Index (BMI) with the difference between free and working days in sleep times, but this difference was smaller in the homozygotes for the minor allele. Moreover, BMI above 30 (obesity) was revealed in the majority of these homozygotes and in the minority of homozygotes for the major allele (11 of 21 or 52.4% and 3 of 40 or 7.5%, respectively). Further studies are required to replicate these results and to elucidate the mechanisms linking NPAS2ʹpolymorphism in with obesity in shift workers.

Are Supplementation of Omega-3 and Ascorbic Acid Effective in Reducing Oxidative Stress and Depression among Depressed Shift Workers?

This study assessed the effect of supplementation of omega-3 fatty acids and ascorbic acid alone and in combination on the level of lipid peroxidation (malondialdehyde, MDA concentration), total antioxidant capacity (TAC) and depression scores in depressed rotational shift workers in the Tehran Shahid Tondgoyan Oil refinery. In this randomized, double-blind, placebo-controlled trial, 136 men who met the inclusion and exclusion criteria and had a Beck Depression Inventory (BDI) score ≥ 10 were selected. Among the participants, 33 received omega-3 fatty acid soft gel (1000 mg twice daily) with vitamin C (250 mg twice daily) (group 1), 31 took omega-3 fatty acid supplements and vitamin C placebo (group 2), 30 took omega-3 fatty acid supplement placebo and vitamin C (group 3), and 32 received omega-3 fatty acid supplement placebo and vitamin C placebo (group 4) for 2 months. Measured were serum MDA, TAC concentrations, and BDI scores at baseline and after 2 months. This study showed that the BDI score was reduced significantly in all 4 groups, however, the level of decrease was more in the omega-3 fatty acid (alone) supplementation group (mean 6.29 score decrease) (p < 0.001). MDA level decreased significantly in groups with omega-3 fatty acids (mean 0.78 μmol/L ± 1.64 μmol/L decrease) (p = 0.014) or vitamin C supplementation alone (mean 0.74 μmol/L ± 1.55 μmol/L decrease) (p = 0.014), but not in combination. Supplementation of omega-3 fatty acids alone and not in combination with vitamin C had a better impact on depression and MDA level pronounced in depressed male shift workers.

Total Antioxidant Capacity and Malondialdehyde in Depressive Rotational Shift Workers

Shift work is associated with sleep deprivation, occupational stress, and increased risk of depression. Depressed patients show increased oxidative stress. During excessive oxidative stress, Malondialdehyde (MDA) increases and total antioxidant capacity (TAC) decreases in body. This cross-sectional study was conducted to determine the serum level of TAC and MDA among depressed rotational shift workers in Shahid Tondooyan Tehran Oil Refinery. 21-item Beck Depression Inventory was used to measure depression level. The level of TAC and MDA was measured by 8 mL fasting blood sample. MDA was determined by thiobarbituric acid reaction. Serum total antioxidants were measured using the ABTS. Results of this study showed that TAC mean and standard deviation concentration was 2.451 (±0.536) mg/dL and MDA was 3.725 (±1.098) mic·mol/L, and mean and standard deviation of depression score and BMI were 14.07 (±3.84) and 24.92 (±3.65) kg/m2, respectively. Depression score had a positive correlation with rotational shift work experience and work experience (r = 0.218 and r = 0.212), respectively, (P < 0.05).

Serum Level of Cortisol, hsCRP and IL-6 in Depressed Rotational Shift Workers

Background: Depression and sleep disorders are more prevalent among rotational shift workers than regular day workers. People with sleep disorders have higher inflammatory and pre-inflammatory cytokines than those in the control group. Objectives: The present study was conducted to investigate serum level of high sensitivity C-reactive protein (hsCRP), Interleukin-6 (IL-6) and cortisol among depressed rotational shift workers at Iran petroleum industry. Materials and Methods: In this cross sectional study, 136 shift workers were studied based on the inclusion and exclusion criteria. Demographic information was collected using a self-administered general questionnaire and depression score was gathered according to 21-question Beck depression inventory. Also, weight and height were measured to calculate body mass index and history of disease was collected based on their occupation profile at health center of Tehran Shahid Tondgoyan oil refinery. Results: Mean and standard deviation of serum concentration of hsCRP, IL-6 and cortisol were 1.03 ± 1.56, 1.24 ± 1.24 and 13.12 ± 3.93 respectively; while mean and standard deviation of depression score and BMI were 14.07 ± 3.84 and 24.92 ± 3.65, respectively. Depression score had a positive correlation with rotational shift work experience and work experience (r = 0.218 and r = 0.212, respectively, P < 0.05). An inverse relation was found between serum concentrations of cortisol and age, work experience and BMI (r = -0.236 and P < 0.05, r = -0.174 and P < 0.05, r = -0.288 and P < 0.05, respectively). IL-6 and hsCRP had a positive relation with each other (r = 0.616, P < 0.001). Serum concentration of hsCRP had a positive correlation with BMI (r = 0.241, P < 0.01). Conclusions: There was no significant correlation between depression score and inflammatory markers among depressed shift workers. However, depression score had a significant correlation with shift work experience.

Restless Legs Syndrome in shift workers: A cross sectional study on male assembly workers

BackgroundRestless Legs Syndrome (RLS) is a common neurological movement disorder characterized by symptoms that follow a circadian pattern. Night and rotating shift work schedules exert adverse effects on functions of the human body by disturbing circadian rhythms, and they are known to cause sleep disturbances and insomnia. In this paper, we investigate the possible association between shift work and RLS.MethodsThis cross sectional study was conducted in an automobile manufacturing factory in Tehran, Iran. A total of 780 male assembly workers were recruited in three groups, each with 260 workers: workers on a permanent morning shift (A) and two different rotating shift schedules (B and C) with morning, afternoon and night shifts. We used the international RLS study group criteria for diagnosis of RLS, and the severity scale for severity assessment in subjects with RLS. Self administered questionnaires were used to gather information on age, smoking, work history, medical condition, and existence and severity of RLS symptoms.ResultsThe prevalence of RLS was significantly higher in rotational shift workers (15%) than workers with permanent morning work schedule (8.5%). In workers suffering from RLS, we found greater mean values of age and work experience, higher percentages of drug consumption, smoking, and co-morbid illnesses compared with subjects who did not have RLS, although these differences were statistically significant only for age, work experience and drug consumption.ConclusionRotational shift work acts as a risk or exacerbating factor for Restless Legs Syndrome.

Assessment of cardiovascular risk in shift healthcare workers

Shift work has been associated with an increased risk of cardiovascular disease (CVD); in particular, night work affects the circadian rhythm. The study examines the effectiveness of three screening methods and plasma hyperhomocysteinemia, an independent risk factor, in assessing the risk of CVD in 147 healthcare providers doing daytime or rotational shift work. The methods applied were: (i) the method proposed by the European Cardiovascular Indicators Surveillance Set (EUROCISS); (ii) the metabolic syndrome (MS) criteria of the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATPIII) and (iii) the MS criteria of the International Diabetes Federation (IDF). EUROCISS was unable to distinguish between the CVD risk of daytime and rotational shift workers. Both the ATPIII and the IDF detected MS, which is strongly associated with CVD, but only the IDF evidenced a significantly greater prevalence of MS (P<0.05) among shift workers. Hyperhomocysteinemia was unable to discriminate the CVD risk between daytime and shift workers, as it was influenced by multiple confounding factors. The increased risk of CVD associated with shift work is related to the greater incidence of MS among these workers. In our study a high prevalence of MS was detected only with the IDF. The method is useful for CVD prevention and the promotion of health during any medical examination of shift workers.

Dynamics of a Multistage Circadian System

Tissues throughout the body exhibit circadian rhythms, forming a multioscillatory system whose disruption results in jet lag and other health problems in travelers and rotational shift workers. The authors' simulations of the dynamics of a multistage circadian system (based on experimental results for nocturnal rodents) reveal the flexibility and stability inherent in a multistage system, as well as potential pitfalls. The modeling predicts that jet lag tends to be most severe following an eastward change of 5 to 8 time zones due to prolonged desynchrony of the system. This desynchrony is partly due to differing reentrainment rates among components, but a much greater source of desynchrony is the antidromic reentrainment of some but not all components (reentrainment by partition), triggered by the overshoot of the master pacemaker's phase in response to these advances. Based on the multistage system dynamics, the authors design a simple protocol that results in a more orderly transition that avoids antidromic reentrainment in all components, thereby reducing the reentrainment time from nearly 2 weeks to just a few days for the most difficult shifts. The authors compare the predicted behavior of self-sustaining versus damped oscillatory components in the system as well as the effect of weak versus strong coupling from the master pacemaker to the peripheral components.