scholarly journals Disturbance of the Circadian System in Shift Work and Its Health Impact

2021 ◽  
pp. 074873042110642
Author(s):  
Diane B. Boivin ◽  
Philippe Boudreau ◽  
Anastasi Kosmadopoulos
Keyword(s):  
Circadian Clock ◽  
Human Genome ◽  
Shift Work ◽  
Clock Genes ◽  
Night Shift ◽  
Circadian System ◽  
Work Schedules ◽  
Shift Workers ◽  
Night Shift Work ◽  
Circadian Clock Genes

The various non-standard schedules required of shift workers force abrupt changes in the timing of sleep and light-dark exposure. These changes result in disturbances of the endogenous circadian system and its misalignment with the environment. Simulated night-shift experiments and field-based studies with shift workers both indicate that the circadian system is resistant to adaptation from a day- to a night-oriented schedule, as determined by a lack of substantial phase shifts over multiple days in centrally controlled rhythms, such as those of melatonin and cortisol. There is evidence that disruption of the circadian system caused by night-shift work results not only in a misalignment between the circadian system and the external light-dark cycle, but also in a state of internal desynchronization between various levels of the circadian system. This is the case between rhythms controlled by the central circadian pacemaker and clock genes expression in tissues such as peripheral blood mononuclear cells, hair follicle cells, and oral mucosa cells. The disruptive effects of atypical work schedules extend beyond the expression profile of canonical circadian clock genes and affects other transcripts of the human genome. In general, after several days of living at night, most rhythmic transcripts in the human genome remain adjusted to a day-oriented schedule, with dampened group amplitudes. In contrast to circadian clock genes and rhythmic transcripts, metabolomics studies revealed that most metabolites shift by several hours when working nights, thus leading to their misalignment with the circadian system. Altogether, these circadian and sleep-wake disturbances emphasize the all-encompassing impact of night-shift work, and can contribute to the increased risk of various medical conditions. Here, we review the latest scientific evidence regarding the effects of atypical work schedules on the circadian system, sleep and alertness of shift-working populations, and discuss their potential clinical impacts.

scholarly journals Modeling the circadian regulation of the immune system: sexually dimorphic effects of shift work

2020 ◽  
Author(s):  
Stéphanie M.C. Abo ◽  
Anita T. Layton
Keyword(s):  
Mathematical Model ◽  
Immune System ◽  
Circadian Clock ◽  
Shift Work ◽  
Acute Inflammation ◽  
Clock Genes ◽  
Work Schedules ◽  
Shift Workers ◽  
Natural Sleep ◽  
Males And Females

AbstractThe circadian clock exerts significance influence on the immune system and disruption of circadian rhythms has been linked to inflammatory pathologies. shift workers often experience circadian misalignment as their irregular work schedules disrupt the natural sleep-wake cycle, which in turn can cause serious health problems associated with alterations in genetic expressions of clock genes. In particular, shift work is associated with impairment in immune function, and those alterations are sex-specific. The goal of this study is to better understand the mechanisms that explain the weakened immune system in shift workers. To achieve that goal, we have constructed a mathematical model of the mammalian pulmonary circadian clock coupled to an acute inflammation model. shift work was simulated by an 8h-phase advance of the circadian system with sex-specific modulation of clock genes. The model reproduces the clock gene expression in the lung and the immune response to various doses of lipopolysaccharide (LPS). Under normal conditions, our model predicts that a host is more sensitive to LPS at CT12 versus CT0 due to a change in the dynamics of IL-10. We identify REV-ERB as a key modulator of IL-10 activity throughout the circadian day. The model also predicts a reversal of the times of lowest and highest sensitivity to LPS, with males and females exhibiting an exaggerated response to LPS at circadian time (CT) 0, which is countered by a blunted immune response at CT12. Overall, females produce fewer pro-inflammatory cytokines than males, but the extent of sequelae experienced by males and females varies across the circadian day. This model can serve as an essential component in an integrative model that will yield mechanistic understanding of how shift work-mediated circadian disruptions affect the inflammatory and other physiological responses.Author summaryShift work has a negative impact on health and can lead to chronic diseases and illnesses. Under regular work schedules, rest is a night time activity and work a daytime activity. Shift work relies on irregular work schedules which disrupt the natural sleep-wake cycle. This can in turn disrupt our biological clock, called the circadian clock, a network of molecular interactions generating biochemical oscillations with a near 24-hour period. Clock genes regulate cytokines before and during infection and immune agents can also impact the clock function. We provide a mathematical model of the circadian clock in the lung coupled to an acute inflammation model to study how the disruptive effect of shift work manifests itself in males and females during inflammation. Our results show that the extent of sequelae experienced by male and female mice depends on the time of infection. The goal of this study is to provide a mechanistic insight of the dynamics involved in the interplay between these two systems.

scholarly journals O4A.5 Night shift work is associated with abnormal liver function

2019 ◽  
Vol 76 (Suppl 1) ◽  
pp. A33.2-A33
Author(s):  
Lap Ah Tse ◽  
Feng Wang ◽  
Liuzhuo Zhang ◽  
Zhimin Li
Keyword(s):  
Liver Function ◽  
Shift Work ◽  
Night Shift ◽  
Abnormal Liver Function ◽  
Baseline Survey ◽  
Shift Workers ◽  
Night Shift Work ◽  
Logistic Regression Models ◽  
Biochemical Analyzer ◽  
Stratified Analysis

ObjectiveTo examine the relationship between night shift work and elevated level of alanine transaminase (e-ALT) of workers, stratified by status of non-alcohol fatty liver.MethodsWe established a prospective cohort of night shift workers in Shenzhen, China. All 4740 male workers who had liver function data from the baseline survey of this night shift workers’ cohort were included in the current analysis. We collected information on demographics, lifestyles, and lifetime working schedule from standardized questionnaire. We examined workers’ NAFL status using liver sonography and their serum ALT levels using the automatic biochemical analyzer. Unconditional logistic regression models were used to evaluate odds ratios (ORs) and 95% confidence interval (95% CI).ResultsThis cohort contained 39.5% night shift workers. Compared with the day workers, night shift workers had higher odds of e-ALT (OR: 1.18; 95% CI 1.00–1.40). Stratified analysis showed that a positive gradient between night shift years and elevated e-ALT was only restricted to the night shift workers without NAFL. No similar trend was observed among those with NAFL.ConclusionsNight shift work is positively associated with the abnormal liver function in workers without NAFL, which indicates that shift work involving circadian disruption is likely to affect abnormal liver function.[National Natural Science Foundation of China (Project number 81273172 and 81372964), [email protected] (Lap Ah Tse)]

Relationship of work-related stress with obesity among Brazilian female shift workers

2020 ◽  
pp. 1-7
Author(s):  
Janaína Cristina da Silva ◽  
Anderson Garcez ◽  
Gabriela Herrmann Cibeira ◽  
Heloísa Theodoro ◽  
Maria Teresa Anselmo Olinto
Keyword(s):  
Shift Work ◽  
Night Shift ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Work Related Stress ◽  
Shift Workers ◽  
Night Shift Work ◽  
Work Related ◽  
Prevalence Of Obesity ◽  
Related Stress

Abstract Objectives: To explore the relationship between work-related stress and obesity among female shift workers. Additionally, we also aimed to test the interaction between shift work and work-related stress in this association. Design: A cross-sectional study was conducted among Brazilian female shift workers. Work-related stress was assessed through a demand–control questionnaire (Job Stress Scale). Work-related stress was defined by the presence of high psychological demands and low control at work. The obesity cases were defined as those with a BMI of 30 kg/m2 or more. Multivariate Poisson regression with robust variance was used to obtain the prevalence ratios (PR) and their respective 95 % CI. Setting: A group of industries located in southern Brazil in 2017. Participants: Four hundred and twenty female workers aged 18–59 years. Results: The overall prevalence of obesity was 30 % (95 % CI: 25·6, 34·4), and the presence of work-related stress was identified in 24 % (95 % CI: 19·9, 28·1) of the sample. We found an indication of interaction between work-related stress and night shift work on obesity (P = 0·026). After adjusting for confounding factors, work-related stress was associated with a 71 % greater probability of obesity (PR = 1·71; 95 % CI: 1·02, 2·87; P = 0·042) among female night shift workers. Conclusions: In this study, we revealed that exposure to work-related stress and night shift work were associated with obesity among female shift workers. Furthermore, the prevalence of obesity was high among female shift workers.

scholarly journals Impacts of shift work: A study in textile companies in Portugal

2017 ◽  
Vol 1 (1) ◽  
pp. 69-78
Author(s):  
I. S. Silva ◽  
J. Keating ◽  
D. Costa
Keyword(s):  
Shift Work ◽  
Social Life ◽  
Sleep Disturbances ◽  
Night Shift ◽  
The Other ◽  
Work Schedules ◽  
Textile Workers ◽  
Shift Workers ◽  
Work Shifts ◽  
Morning Shift

Shift work, especially if it involves night work and/or weekend work, may represent disadvantages for workers and their families at the level of family, social life, and health. The present study evaluates the impacts of three work shifts (morning, afternoon and night) on sleep, family and social life as well as satisfaction with work schedules. In total, 373 Portuguese textile workers participated in this study; all were men. The results indicated that night shift workers had greater sleep disturbances and less satisfaction with their work schedules. On the other hand, morning shift workers were most satisfied with family and social life in association with their work schedules. Based on the results, implications of the practice have been reflected.

scholarly journals 0025 Circadian Dysregulation of DNA Repair and Increased Endogenous and Exogenous Sensitivity to DNA Damage Precipitate Elevated Cancer Risk Associated with Night Shift Work

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A10-A10
Author(s):  
H Van Dongen ◽  
B Koritala ◽  
J E McDermott ◽  
K I Porter ◽  
O A Arshad ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Cancer Risk ◽  
Shift Work ◽  
Clock Genes ◽  
Night Shift ◽  
Night Shift Work ◽  
Shift Schedule ◽  
Γh2ax Foci ◽  
Damage Response

Abstract Introduction The elevated cancer risk associated with night shift work is poorly understood. To investigate whether circadian disruption may play a role, we assessed the circadian transcriptome and its association with hallmark cancer pathways, as well as sensitivity to endogenous and exogenous sources of DNA damage, after in-laboratory simulated shift work. Methods N=14 healthy humans (aged 22-34y; 10m, 4f) were exposed to a simulated night shift schedule (daytime sleep: 10:00-18:00) or a simulated day shift schedule (nighttime sleep: 22:00-06:00) for 3 days (n=7 in each condition). After the simulated shift schedule, subjects underwent a 24h constant routine protocol, during which blood was collected every 3h. Lymphocytes were extracted from the blood samples and subjected to transcriptome analysis using a NanoString multiplex assay. We evaluated 726 mRNA cancer hallmark targets (NanoString PanCancer Pathway Panel) and 17 circadian clock genes, with 18 arrhythmic internal controls. Gene expression was analyzed for circadian rhythmicity using mixed-effects cosinor analysis. Further, lymphocytes were investigated for DNA damage using an alkaline comet assay and immunofluorescence assessment of DNA damage response biomarkers BRCA1 and γH2AX. Lymphocytes collected at 07:30 and 19:30 were also exposed to ionizing radiation (2.5Gy) and DNA damage response assessments were repeated. Results Simulated night shift caused widespread disruption of circadian rhythmicity, as measured under constant routine, for core clock genes and the transcriptome of cancer hallmark pathways. The DNA repair pathway showed significant enrichment of rhythmic genes (p<0.05) after the simulated day shift schedule only. Following simulated night shift, lymphocytes showed induction of endogenous DNA damage, with extended tail in the comet assay (p<0.001), and higher percentage of lymphocytes with BRCA1 and γH2AX foci (p<0.01). Lymphocytes collected at 19:30 showed enhanced impact of ionizing radiation as indicated by increased prevalence of cells with BRCA1 and γH2AX foci (p<0.05). Conclusion Circadian dysregulation of DNA repair mechanisms and increased sensitivity to DNA damage following night shift work may increase genomic instability and precipitate elevated cancer risk in night shift workers. Support NIH grants ES022640 and CA227381, CDMRP award W81XWH-18-1-0100, and Pacific Northwest National Laboratory BRAVE investment under DOE contract DE-AC05-76RL01830.

Differential effects of light at night and shift rotation pattern on the circadian system in night workers.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 1556-1556
Author(s):  
Pedram Razavi ◽  
Eva S Schernhammer ◽  
Keyword(s):  
Shift Work ◽  
Night Shift ◽  
Circadian System ◽  
Activity Level ◽  
Melatonin Level ◽  
Consecutive Night ◽  
Light At Night ◽  
Night Shift Work ◽  
Single Night ◽  
Night Shifts

1556 Background: Light at night as in shift work suppresses nocturnal secretion of melatonin, a pineal hormone with oncostatic properties. Several studies have associated night shift work with higher risk of cancer, leading WHO in 2007 to classify rotating night shift work as “probably carcinogenic”. We conducted one of the most comprehensive studies, to date, to evaluate the effects of light and night shift work on melatonin measurements in the field. Methods: Study participants were 130 active nurses (84 current rotating night shift workers and 46 day shift workers) participating in NHS2. Each nurse wore a head-mounted light- and accelerometer for a 3-day study period, during which each spontaneous urine was collected for repeated urinary 6-sulfatoxymelatonin (melatonin) measurements. In addition, nurses were asked to fill out paper questionnaires and diaries. We used mixed models to evaluate the influence of light, activity and night shift work on urinary melatonin level adjusting, for age, lifestyle, and occupational history. We log-transformed main variables and report geometric means (GM [standard deviation]). Results: Greater levels of light were associated with lower melatonin (P < 0.0001), independent of activity level. An increase in light intensity from 10 to 100 lux was associated with a 12% decrease in geometric mean of melatonin level; however, this inverse association was only significant at night (Ptrend = 0.01). At night, each hour increase in exposure to ≥ 20 lux light lowered melatonin level by 5.7% (Ptrend < 0.0001). A single night shift affected the circadian system by lowering melatonin peak by 22% (day shift: GM = 17.57 [2.73]; night shift: GM = 13.64 [2.54]) and induced a phase shift (PS) of 0.9 hours, -changes that reset to normal by the next day. Two consecutive night shifts had a similar effect as a single shift. However, the effect was worse after three consecutive night shifts (GM = 10.11 [2.77]; PS = 2.2 hours). Conclusions: We found significant inverse associations of intensity and duration of exposure to light at night with urinary melatonin, independent of activity level. Three consecutive night shifts affected the circadian system more strongly than two consecutive, or a single night shift.

scholarly journals Exosomes and Metabolic Function in Mice Exposed to Alternating Dark-Light Cycles Mimicking Night Shift Work Schedules

2017 ◽  
Vol 8 ◽  
Author(s):  
Abdelnaby Khalyfa ◽  
Valeriy A. Poroyko ◽  
Zhuanhong Qiao ◽  
Alex Gileles-Hillel ◽  
Ahamed A. Khalyfa ◽  
...  
Keyword(s):  
Shift Work ◽  
Night Shift ◽  
Metabolic Function ◽  
Work Schedules ◽  
Dark Light ◽  
Night Shift Work

Association between night-shift work, sleep quality and metabolic syndrome

2018 ◽  
Vol 75 (10) ◽  
pp. 716-723 ◽  
Author(s):  
Yin Cheng Lim ◽  
Victor C W Hoe ◽  
Azlan Darus ◽  
Nirmala Bhoo-Pathy
Keyword(s):  
Metabolic Syndrome ◽  
Sleep Quality ◽  
Shift Work ◽  
Sleep Disturbances ◽  
Night Shift ◽  
Future Research ◽  
Global Score ◽  
Early Screening ◽  
Shift Workers ◽  
Night Shift Work

ObjectivesOccupational factors, particularly night-shift work, are attracting growing interest as a possible determinant of metabolic syndrome (MetS). This study aimed to determine the association between night-shift work and MetS, and assess whether sleep quality is a mediating factor.MethodsA cross-sectional study was conducted among Malaysian manufacturing workers, aged 40–65 years old. They completed a self-administered questionnaire on sociodemographics, lifestyle and family history, and the Pittsburgh Sleep Quality Index (PSQI) questionnaire. Waist circumference, blood pressure, fasting blood sugar, triglycerides and high-density lipoprotein levels were measured. Baron and Kenny’s method, Sobel test and multiple mediation models with bootstrapping were used to determine whether the PSQI global score or its components mediated the association between night-shift work and MetS.ResultsOf the 494 participants, 177 (36%) worked night shift and 51% were men. The prevalence of MetS was 37%. Night-shift work was independently associated with a twofold increase in the risk of MetS (adjusted OR: 1.92, 95% CI 1.24 to 2.97). However, the association between night-shift work and MetS did not appear to be modified by sex. Night-shift workers also reported significantly poorer sleep quality, longer sleep latency, shorter sleep duration, sleep disturbances and daytime dysfunction. Robust mediation analysis nonetheless showed that neither PSQI global score nor its components mediated the association between night-shift work and MetS.ConclusionEarly screening and management of MetS and the development of programmes to improve sleep quality should be carried out among night-shift workers. Future research should investigate other modifiable mediators linking night-shift work and MetS.

scholarly journals Immunological effects of shift work in healthcare workers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Bette Loef ◽  
Nening M. Nanlohy ◽  
Ronald H. J. Jacobi ◽  
Chantal van de Ven ◽  
Rob Mariman ◽  
...  
Keyword(s):  
T Cells ◽  
Shift Work ◽  
Cd8 T Cells ◽  
Healthcare Workers ◽  
Night Shift ◽  
T Cell Subsets ◽  
Shift Workers ◽  
Night Shift Work ◽  
Adverse Health Effects ◽  
Immunological Effects

AbstractThe immune system potentially plays an important mechanistic role in the relation between shift work and adverse health effects. To better understand the immunological effects of shift work, we compared numbers and functionality of immune cells between night-shift and non-shift workers. Blood samples were collected from 254 night-shift and 57 non-shift workers employed in hospitals. Absolute numbers of monocytes, granulocytes, lymphocytes, and T cell subsets were assessed. As read out of immune function, monocyte cytokine production and proliferative capacity of CD4 and CD8 T cells in response to various stimuli were analysed. The mean number of monocytes was 1.15 (95%-CI = 1.05–1.26) times higher in night-shift than in non-shift workers. Furthermore, night-shift workers who worked night shifts in the past three days had a higher mean number of lymphocytes (B = 1.12 (95%-CI = 1.01–1.26)), T cells (B = 1.16 (95%-CI = 1.03–1.31)), and CD8 T cells (B = 1.23 (95%-CI = 1.05–1.45)) compared to non-shift workers. No differences in functional parameters of monocytes and lymphocytes were observed. The differences in numbers of monocytes and T cells suggest that chronic exposure to night-shift work as well as recent night-shift work may influence the immune status of healthcare workers. This knowledge could be relevant for preventive initiatives in night-shift workers, such as timing of vaccination.

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

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261349
Author(s):  
Wan-Ju Cheng ◽  
Chiu-Shong Liu ◽  
Kai-Chieh Hu ◽  
Yu-Fang Cheng ◽  
Kati Karhula ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Shift Work ◽  
Night Shift ◽  
Working Time ◽  
Health Examination ◽  
Long Term Effects ◽  
Time Data ◽  
Shift Workers ◽  
Night Shift Work ◽  
Night Shifts

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.

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