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Abo SMC, Layton AT. Modeling the circadian regulation of the immune system: Sexually dimorphic effects of shift work. PLoS Comput Biol 2021; 17:e1008514. [PMID: 33788832 PMCID: PMC8041207 DOI: 10.1371/journal.pcbi.1008514] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 04/12/2021] [Accepted: 03/06/2021] [Indexed: 12/31/2022] Open
Abstract
The 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 light-dark 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 in the male and female rats. 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 circadian time (CT) CT12 versus CT0 due to a dynamic change of Interleukin 10 (IL-10), an anti-inflammatory cytokine. 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 CT0, 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.
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Affiliation(s)
- Stéphanie M. C. Abo
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Anita T. Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
- Department of Biology, Cheriton School of Computer Science, and School of Pharmacology, University of Waterloo, Waterloo, Ontario, Canada
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Chung Y, Kim H, Koh DH, Park JH, Yoon S. Relationship Between Shift Intensity and Insomnia Among Hospital Nurses in Korea: A Cross-sectional Study. J Prev Med Public Health 2021; 54:46-54. [PMID: 33618499 PMCID: PMC7939760 DOI: 10.3961/jpmph.20.555] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 11/26/2020] [Indexed: 12/11/2022] Open
Abstract
Objectives This study explored the relationship between shift intensity and insomnia among hospital nurses. Methods The participants were 386 female hospital nurses who underwent a special health examination for night workers in 2015. The Korean Insomnia Severity Index (ISI), indices of shift work intensity, and other covariates such as amount of exercise, level of alcohol consumption, employment duration, and hours worked were extracted from the health examination data. The indices for shift intensity were (1) number of 3 consecutive night shifts and (2) number of short recovery periods after a previous shift, both assessed over the prior 3 months. Multiple logistic regression analysis adjusted for the aforementioned covariates was performed to evaluate the association of shift intensity with insomnia, defined as an ISI score of ≥8. Results The nurses with insomnia tended to be younger (p=0.029), to have worked 3 consecutive night shifts more frequently (p<0.001), to have experienced a greater number of short recovery periods after the previous shift (p=0.021), and to have worked for more hours (p=0.006) than the nurses without insomnia. Among the other variables, no statistically significant differences between groups were observed. Experiences of 3 or more consecutive night shifts (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.29 to 4.20) and 3 or more short recovery periods (OR, 2.01; 95% CI, 1.08 to 3.73) were associated with increased odds of insomnia. Conclusions The results suggest that decreasing the shift intensity may reduce insomnia among hospital nurses working rotating shifts.
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Affiliation(s)
- Yuhjin Chung
- Department of Preventive Medicine, Graduate School of Public Health, Seoul National University, Seoul, Korea
| | - Hyunjoo Kim
- Department of Occupational and Environmental Medicine, Ewha Womans University Mokdong Hospital, Seoul, Korea
| | - Dong-Hee Koh
- Department of Occupational and Environmental Medicine, International St. Mary's Hospital, Incheon, Korea
| | - Ju-Hyun Park
- Department of Statistics, Dongguk University, Seoul, Korea
| | - Seohyun Yoon
- Ewha Medical Research Institute, Ewha Womans University School of Medicine, Seoul, Korea
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Pallesen S, Jacobsen DP, Nielsen MB, Gjerstad J. The 5-HTTLPR rs25531 L AL A-genotype increases the risk of insomnia symptoms among shift workers. Sleep Med 2019; 60:224-229. [PMID: 31213395 DOI: 10.1016/j.sleep.2019.04.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 04/12/2019] [Accepted: 04/15/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND Previous studies indicate that shift work tolerance may be associated with individual factors including genetic variability in the gene encoding the serotonin transporter 5-HTT (SLC6A4). The present study aimed to explore the interaction between work schedule (shift work versus non-shift work), genetic variability in SLC6A4 and insomnia symptoms. METHODS The study was based on a national probability sample survey of 987 Norwegian employees drawn from The Norwegian Central Employee Register by Statistics Norway. Insomnia symptoms were assessed by three items reflecting problems with sleep onset, sleep maintenance, and early morning awakenings. Genotyping concerning SLC6A4 (the 5-HTTLPR S versus L and the SNP rs25531 A versus G) was carried out using a combination of gel-electrophoresis and TaqMan assay. RESULTS Using the LALA genotype as a reference a main effect of the SS genotype (B = 0.179; 95% CI = 0.027-0.330) was found. In addition, a main effect of work schedule (0 = non shift, 1 = shift work) was found (B = 0.504; 95% CI = 0.185-0.823). The genotype x work schedule interaction was significant for all genotypes; SLA (B = -0.590; 95% CI = -0.954-0.216), LALG (B = -0.879; 95% CI = -1.342-0.415), SLG (B = -0.705; 95% CI = -1.293-0.117) and SS (B = -0.773; 95% CI = -1.177-0.369) indicating higher insomnia symptom scores among LALA-participants compared to participants with other genotypes when working shifts. CONCLUSIONS The ability to cope with shift work is associated with the combination of the SLC6A4 variants 5-HTTLPR and SNP rs25531. Our findings demonstrated that the LALA-genotype increases the risk of insomnia symptoms among shift workers.
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Affiliation(s)
- Ståle Pallesen
- Department for Psychosocial Science, University of Bergen, Norway; Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Norway.
| | | | - Morten B Nielsen
- Department for Psychosocial Science, University of Bergen, Norway; National Institute of Occupational Health, Oslo, Norway
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Booker LA, Magee M, Rajaratnam SMW, Sletten TL, Howard ME. Individual vulnerability to insomnia, excessive sleepiness and shift work disorder amongst healthcare shift workers. A systematic review. Sleep Med Rev 2018; 41:220-233. [PMID: 29680177 DOI: 10.1016/j.smrv.2018.03.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/16/2018] [Accepted: 03/21/2018] [Indexed: 12/21/2022]
Abstract
Shift workers often experience reduced sleep quality, duration and/or excessive sleepiness due to the imposed conflict between work and their circadian system. About 20-30% of shift workers experience prominent insomnia symptoms and excessive daytime sleepiness consistent with the circadian rhythm sleep disorder known as shift work disorder. Individual factors may influence this vulnerability to shift work disorder or sleep-related impairment associated with shift work. This paper was registered with Prospero and was conducted using recommended standards for systematic reviews and meta-analyses. Published literature that measured sleep-related impairment associated with shift work including reduced sleep quality and duration and increased daytime sleepiness amongst healthcare shift workers and explored characteristics associated with individual variability were reviewed. Fifty-eight studies were included. Older age, morning-type, circadian flexibility, being married or having children, increased caffeine intake, higher scores on neuroticism and lower on hardiness were related to a higher risk of sleep-related impairment in response to shift work, whereas physical activity was a protective factor. The review highlights the diverse range of measurement tools used to evaluate the impact of shift work on sleep. Use of standardised and validated tools would enable cross-study comparisons. Longitudinal studies are required to establish causal relationships between individual factors and the development of shift work disorder.
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Affiliation(s)
- Lauren A Booker
- Institute for Breathing and Sleep, Austin Health, Austin Hospital, Heidelberg, Victoria, Australia; School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia; Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Victoria, Australia.
| | - Michelle Magee
- School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia; Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Victoria, Australia
| | - Shantha M W Rajaratnam
- School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia; Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Victoria, Australia
| | - Tracey L Sletten
- School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia; Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Victoria, Australia
| | - Mark E Howard
- Institute for Breathing and Sleep, Austin Health, Austin Hospital, Heidelberg, Victoria, Australia; School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia; Cooperative Research Centre for Alertness, Safety and Productivity, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
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Waage S, Pallesen S, Moen BE, Bjorvatn B. Restless Legs Syndrome/Willis-Ekbom Disease Is Prevalent in Working Nurses, but Seems Not to Be Associated with Shift Work Schedules. Front Neurol 2018; 9:21. [PMID: 29434568 PMCID: PMC5796891 DOI: 10.3389/fneur.2018.00021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/11/2018] [Indexed: 01/04/2023] Open
Abstract
Insomnia and excessive sleepiness are among the most commonly reported sleep problems related to shift work. Sleep-related movement disorders have, however, received far less attention in relation to such work schedules. The objective of this study was to investigate the association between different shift work schedules and the prevalence of Restless legs syndrome/Willis–Ekbom disease (RLS/WED) in a large sample of Norwegian nurses. Our hypothesis was that shift working nurses would report higher prevalence of RLS/WED compared to day workers. A total of 1,788 nurses with different work schedules (day work, two-shift rotation, night work, three shift rotation) participated in a cohort study, started in 2008/2009. Four questions about RLS/WED based on the diagnostic criteria were included in wave 4 (2012). RLS/WED prevalence rates across different shift schedules were explored by the Pearson chi-square test. Logistic regression analysis was used to assess the association between RLS/WED and work schedules and shift work disorder (SWD) with adjustment for sex, age, marital status, smoking, and caffeine use. In total, 90.0% of the nurses were females, mean age 36.5 years (SD = 8.6, range 25–67). The overall prevalence of RLS/WED was 26.8%. We found no significant differences between the prevalence of RLS/WED across the different shift schedules, ranging from 23.3% (day work) to 29.4% (night work). There was a significant difference (p < 0.001) in the prevalence of RLS/WED between nurses having SWD (33.5%) compared to nurses not having SWD (23.8%). SWD remained significantly associated with RLS/WED in the adjusted logistic regression analysis (1.56, CI: 1.24–1.97). This study did not support the hypothesis. RLS/WED was associated with SWD, which might indicate that nurses vulnerable to shift work also are sensitive to other complaints related to a misalignment of the biological clock.
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Affiliation(s)
- Siri Waage
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.,Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway
| | - Ståle Pallesen
- Department of Psychosocial Science, University of Bergen, Bergen, Norway
| | - Bente Elisabeth Moen
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.,Centre for International Health, University of Bergen, Bergen, Norway
| | - Bjørn Bjorvatn
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.,Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway
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