Shift Work and Respiratory Infections in Health-Care Workers

The Impact of Night Work on the Sleep and Health of Medical Staff-A Review of the Latest Scientific Reports

Introduction: Employees working in shifts are exposed to many threats affecting their health, quality of life and safety at work. Those who perform their work only at night are particularly vulnerable. The purpose of the review is to identify risks to the health, quality of life and sleep of shift health workers. Method: A systematic review (SR) was used in the analysis. Electronic databases were searched. The search was limited to the latest studies published in the last five years: 2019-2023. Results: Finally, 36 articles were included in the review. Most authors have shown a link between sleep disturbance or its quality and shift work/night work. Moreover, a three-shift schedule was the most significant factor for poorer subjective sleep quality when compared to other work schedules. Furthermore, many authors have shown a link between shift/night work and health problems, which include cardiometabolic risk, glucose intolerance, breast cancer and immune vulnerability. Conclusions: The research results clearly show a significant impact of night work on the increased risk of sleep disorders and health disturbance. Healthcare workers should be aware of the risks associated with night work in order to take measures preventing sleep/health problems. Shift/night workers should have the opportunity to be screened for disorders linked with their work.

Sleep quality, sleep duration, and sleep disturbances among hospital night workers: a prospective cohort study

PURPOSE

This study aimed to assess among hospital night workers (i) to what extent sleep quality, sleep duration and sleep disturbances overlap, and (ii) associations between sociodemographic factors, lifestyle factors and work characteristics and sleep components.

METHODS

Data were used from 467 hospital night workers participating in the Klokwerk + study, a prospective cohort study with two measurements. Sleep quality was measured by the Pittsburgh Sleep Quality Index, sleep duration and sleep disturbances were measured by the Medical Outcomes Study Sleep Scale. The overlap between the three sleep measures was visualized with a Venn diagram and the proportions of overlap was calculated. Associations between independent variables (sociodemographic factors, lifestyle factors and work characteristics) and the three sleep outcomes were estimated using between-within Poisson regression models.

RESULTS

About 50% of the hospital night workers had at least one poor sleep outcome. Overlap in poor sleep outcomes was apparent for 36.8% of these workers, while the majority had a poor outcome in one of the sleep components only (63.1%). Former smoking had a significant association with poor sleep quality. For most independent variables no associations with poor sleep outcomes were observed.

CONCLUSION

Our findings suggest that sleep quality, sleep duration and sleep disturbances are separate entities and should be studied separately. Lifestyle factors and work characteristics were generally not associated with poor sleep. Since these factors can have an acute effect on sleep, future research should consider ecological momentary assessment to examine how exposure and outcomes (co)vary within-persons, over time, and across contexts. Trial registration Netherlands Trial Register trial number NL56022.041.16.

Associations between long-term night shift work and incidence of chronic obstructive pulmonary disease: a prospective cohort study of 277,059 UK Biobank participants

BACKGROUND

Little is known about the effects of night shifts and their interactions with genetic factors on chronic obstructive pulmonary disease (COPD). In this study, we aim to investigate relationships between long-term night shift work exposure and COPD risk, and assess modification effects of genetic predisposition.

METHODS

A total of 277,059 subjects who were in paid employment or self-employed were included in the UK Biobank. Information on current and lifetime employment was obtained, and a weighted COPD-specific genetic risk score (GRS) was constructed. We used Cox proportional hazard models to investigate associations between night shift work and COPD risk, and their interaction with COPD-specific GRS.

RESULTS

The cohort study included 277,059 participants (133,063 men [48.03%]; mean [SD] age, 52.71 [7.08] years). During a median follow-up of 12.87 years, we documented 6558 incidents of COPD. From day work, irregular night shifts to regular night shifts, there was an increased trend in COPD incidence (P for trend < 0.001). Compared with day workers, the hazard ratio (HR) and 95% confidence interval (CI) of COPD was 1.28 (1.20, 1.37) for subjects with rarely/sometimes night shifts and 1.49 (1.35, 1.66) for those with permanent night shifts. Besides, the longer durations (especially in subjects with night shifts ≥ 10 years) and increasing monthly frequency of night shifts (in workers with > 8 nights/month) were associated with a higher COPD risk. Additionally, there was an additive interaction between night shifts and genetic susceptibility on the COPD risk. Subjects with permanent night shifts and high genetic risk had the highest risk of COPD (HR: 1.90 [95% CI: 1.63, 2.22]), with day workers with low genetic risk as a reference.

CONCLUSIONS

Long-term night shift exposure is associated with a higher risk of COPD. Our findings suggest that decreasing the frequency and duration of night shifts may offer a promising approach to mitigating respiratory disease incidence in night shift workers, particularly in light of individual susceptibility.

Exploration of genome-wide DNA methylation profiles in night shift workers

The past decades, studies indicated that night shift work is associated with adverse health effects, however, molecular mechanisms underlying these effects are poorly understood. A few previous studies have hypothesized a role for DNA-methylation (DNAm) in this relationship. We performed a cross-sectional epigenome-wide association study, to investigate if night shift work is associated with genome-wide DNAm changes and DNAm-based biological age acceleration, based on previously developed so-called 'epigenetic clocks.' Short term (2-6 years) and intermediate term (10-16 years) night shift workers, along with age and sex matched dayworkers (non-shift workers) were selected from the Lifelines Cohort Study. For genome-wide methylation analysis the Infinium Methylation EPIC array (Ilumina) was used. Linear regression analyses were used to detect differences in methylation at individual CpG-sites associated with night shift work. Pathway analysis was performed based on KEGG pathways and predictions of age acceleration in night shift workers were performed based on four previously developed epigenetic age calculators. Only in women, differences in methylation at individual CpG-sites were observed between night shift workers and non-shift workers. Most of these differentially methylated positions (DMPs) were observed in intermediate term night shift workers. Pathway analysis shows involvement of pathways related to circadian rhythm and cellular senescence. Increased age acceleration was observed only in short-term night shift workers (men and women). This might be indicative of adaptation to night shift work or a so-called healthy worker effect. In conclusion, these results show that DNA methylation changes are associated with night shift work, specifically in women.

Sex difference in cardiac performance in individuals with irregular shift work

Background: sex differences existed in animal behavioral adaption and activity rhythms when exposed to chronic disruption of the circadian rhythm. Whether these differences extend to cardiac performance has not been fully investigated by cardiac imaging technology.

Methods

One hundred and thirty patients enrolled in this study. Patients were divided into the day shift (DS) group and the irregular shift (IRS) group based on whether involved in the night shift and the frequency of the night shift. Comparisons of clinical data and cardiac imaging parameters were performed to identify the sex difference in cardiac function in the participants with day shift work or irregular shifts.

Results

The absolute value of GLS was significantly lower in male IRS group than in male DS group. In females, no significant difference was tested in left ventricular function between the two groups. In male participants, Weekly work hours (WWH) was positively correlated with HR (r = 0.51, p = 0.02) and QTc duration (r = 0.68, p < 0.00), and weakly negatively correlated with the GLS (r = -0.38, p = 0.05). Amongst patients, there was a 2.67-fold higher relative risk (RR) for impaired GLS in males than in females, with a 95 % confidence interval (CI) of 1.20-5.61. Moreover, there was an increased risk in the male IRS group compared to the female IRS group to develop impaired GLS (RR:3.14, 95 % CI 1.20-7.84).

Conclusions

The present study suggests that chronic circadian disruption brings cardiac dysfunction in people with night-shift work. Gender differences exist in the impact of circadian rhythmicity on cardiac function and may help to guide the work schedule and breaks in shift workers and bring forward prevention strategies in response to chronic circadian disruption.

Circadian Disruption in Night Shift Work and Its Association with Chronic Pulmonary Diseases

Globalization and the expansion of essential services over continuous 24 h cycles have necessitated the adaptation of the human workforce to shift-based schedules. Night shift work (NSW) causes a state of desynchrony between the internal circadian machinery and external environmental cues, which can impact inflammatory and metabolic pathways. The discovery of clock genes in the lung has shed light on potential mechanisms of circadian misalignment in chronic pulmonary disease. Here, the current knowledge of circadian clock disruption caused by NSW and its impact on lung inflammation and associated pathophysiology in chronic lung diseases, such as asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and COVID-19, is reviewed. Furthermore, the limitations of the current understanding of circadian disruption and potential future chronotherapeutic advances are discussed.

Associations of burnout with job demands/resources during the pandemic in health workers from Southeast European countries

Introduction

Despite several studies assessing job demands and burnout in countries from the Southeast European (SEE) region, there is still a lack of data about the psychological impact of the pandemic on health workers (HWs).

Aims

The present study aimed to demonstrate and compare levels of burnout dimensions in HWs from SEE countries and to reveal the burnout-job demands/resources relationships in these workers during the pandemic.

Materials and methods

During the autumn of 2020, this online multicentric cross-sectional survey studied a large group (N = 4.621) of HWs working in SEE countries. The Maslach Burnout Inventory was used for the measurement of burnout dimensions. We analyzed the job demands by using the Hospital Experience Scale. Remuneration and relationships with superiors were measured using the Questionnaire sur les Ressources et Contraintes Professionnelles (English version).

Results

A series of ANOVA comparisons of means revealed the countries in which respondents showed higher mean values of emotional exhaustion (Bosnia and Herzegovina, Bulgaria, Croatia, Moldova, Montenegro, and North Macedonia) and the countries in which respondents showed lower mean values of this burnout dimension (Israel and Romania) (Welch F = 17.98, p < 0.001). We also found differences among HWs from different countries in job demands and job resources. The testing of hierarchical regression models, which have been controlled for certain confounding factors, clearly revealed that emotional exhaustion was predicted by job demands (R2 = 0.37) and job resources (R2 = 0.16).

Conclusion

Preventive measures for the improvement of mental health in HWs during the pandemic and beyond have to take into account the differences between countries regarding the country context and current scientific knowledge. A modified stress test should be implemented in hospitals regarding future shocks that might include new pandemics, terrorism, catastrophes, or border conflicts.

Uncovering Novel Biomarkers of Inflammation as Potential Screening Targets of Disease Risk in Healthcare Shift Workers: A Pilot Study

Shift work, experienced by nearly 30% of the U.S. workforce, is hazardous to health and has become a pervasive labor practice in the healthcare sector worldwide. It increases the risk of stroke, diabetes, cancer, and cardiovascular disease. Nonetheless, specific screening targets for shift workers still need to be defined. In this study, we have begun uncovering these targets as specific low-grade systemic inflammation markers and functional endotoxin-elicited responses that may foreshadow disease risk in shift workers. One hundred four participants (normothermic and normotensive) were healthy, non-smoking, and drug- and medication-free volunteers recruited from Atlanta area hospitals and medical schools. We assessed the concentration of three proteins in plasma samples from day workers and shift workers (lipopolysaccharide-binding protein, IL-10, and TNF-α), and the relationship between these baseline biomarkers and their response to an ex-vivo endotoxin challenge. We show that shift work increases low-grade systemic inflammation and disrupts discrete endotoxin responses. As shift work exposure increases, the correlation between low-grade systemic inflammation markers and their endotoxin responses was disrupted; this effect was more robust for TNF-α than for IL-10. With increased shift work exposure, these events, alone or combined, represent potential systemic and functional signals that may be harnessed to develop screening tools to identify at-risk individuals.

Consequences of Shift Work and Night Work: A Literature Review

Nonstandard work schedules such as shift work and night work tend to trigger problems for workers in different areas. To illustrate the diversity of areas affected and the relative interest of the scientific community, we conducted a literature review of the effects of shift work and night work on workers. In particular, we intended to identify the main variables addressed in the field of health, the family sphere, and the organizational context. The literature review was carried out using the Web of Science with the following terms: "shift work", "rotating shifts", and "night work". Inclusion criteria incorporated empirical studies and articles written in Portuguese or English published in 2019. We selected 129 of the 619 articles identified. Regarding the impacts of shift work and night work, there existed a high discrepancy of focus between the three defined areas: health, family life, and organizational context. Specifically, health-related variables were the most studied (83.4%), followed by organizational variables (9.2%), and, lastly, family variables (7.4%). Based on these results, it is essential to extend the study of the two underrepresented impacts to other crucial areas, not only for the worker but also for organizations.

Daily activity timing in the Anthropocene

Animals are facing novel 'timescapes' in which the stimuli entraining their daily activity patterns no longer match historical conditions due to anthropogenic disturbance. However, the ecological effects (e.g., altered physiology, species interactions) of novel activity timing are virtually unknown. We reviewed 1328 studies and found relatively few focusing on anthropogenic effects on activity timing. We suggest three hypotheses to stimulate future research: (i) activity-timing mismatches determine ecological effects, (ii) duration and timing of timescape modification influence effects, and (iii) consequences of altered activity timing vary biogeographically due to broad-scale variation in factors compressing timescapes. The continued growth of sampling technologies promises to facilitate the study of the consequences of altered activity timing, with emerging applications for biodiversity conservation.

Influence of electromagnetic fields on the circadian rhythm: Implications for human health and disease

Living organisms have evolved within the natural electromagnetic fields (EMFs) of the earth which comprise the global atmospheric electrical circuit, Schumann resonances (SRs) and the geomagnetic field. Research suggests that the circadian rhythm, which controls several physiological functions in the human body, can be influenced by light but also by the earth's EMFs. Cyclic solar disturbances, including sunspots and seasonal weakening of the geomagnetic field, can affect human health, possibly by disrupting the circadian rhythm and downstream physiological functions. Severe disruption of the circadian rhythm increases inflammation which can induce fatigue, fever and flu-like symptoms in a fraction of the population and worsen existing symptoms in old and diseased individuals, leading to periodic spikes of infectious and chronic diseases. Possible mechanisms underlying sensing of the earth's EMFs involve entrainment via electrons and electromagnetic waves, light-dependent radical pair formation in retina cryptochromes, and paramagnetic magnetite nanoparticles. Factors such as electromagnetic pollution from wireless devices, base antennas and low orbit internet satellites, shielding by non-conductive materials used in shoes and buildings, and local geomagnetic anomalies may also affect sensing of the earth's EMFs by the human body and contribute to circadian rhythm disruption and disease development.

Vitamin D3 Supplementation at 5000 IU Daily for the Prevention of Influenza-like Illness in Healthcare Workers: A Pragmatic Randomized Clinical Trial

Vitamin D supplementation has been shown to reduce the incidence of acute respiratory infections in populations at risk. The COVID-19 pandemic has highlighted the importance of preventing viral infections in healthcare workers. The aim of this study was to assess the hypothesis that vitamin D3 supplementation at 5000 IU daily reduces influenza-like illness (ILI), including COVID-19, in healthcare workers. We conducted a prospective, controlled trial at a tertiary university hospital. A random group of healthcare workers was invited to receive 5000 IU daily vitamin D3 supplementation for nine months, while other random healthcare system workers served as controls. All healthcare workers were required to self-monitor and report to employee health for COVID-19 testing when experiencing symptoms of ILI. COVID-19 test results were retrieved. Incidence rates were compared between the vitamin D and control groups. Workers in the intervention group were included in the analysis if they completed at least 2 months of supplementation to ensure adequate vitamin D levels. The primary analysis compared the incidence rate of all ILI, while secondary analyses examined incidence rates of COVID-19 ILI and non-COVID-19 ILI. Between October 2020 and November 2021, 255 healthcare workers (age 47 ± 12 years, 199 women) completed at least two months of vitamin D3 supplementation. The control group consisted of 2827 workers. Vitamin D3 5000 IU supplementation was associated with a lower risk of ILI (incidence rate difference: -1.7 × 10^-4/person-day, 95%-CI: -3.0 × 10^-4 to -3.3 × 10^-5/person-day, p = 0.015) and a lower incidence rate for non-COVID-19 ILI (incidence rate difference: -1.3 × 10^-4/person-day, 95%-CI -2.5 × 10^-4 to -7.1 × 10^-6/person-day, p = 0.038). COVID-19 ILI incidence was not statistically different (incidence rate difference: -4.2 × 10^-5/person-day, 95%-CI: -10.0 × 10^-5 to 1.5 × 10^-5/person-day, p = 0.152). Daily supplementation with 5000 IU vitamin D3 reduces influenza-like illness in healthcare workers.

GlycA, a Biomarker of Low-Grade Inflammation, Is Increased in Male Night Shift Workers

Sustained night shift work is associated with various adverse health risks, including an increased risk of cardiovascular disease, type II diabetes, and susceptibility to infectious respiratory diseases. The extent of these adverse health effects, however, seems to greatly vary between night shift workers, yet the underlying reasons and the mechanisms underlying these interindividual differences remain poorly understood. Metabolomics assays in the blood have recently gained much attention as a minimally invasive biomarker platform capturing information predictive of metabolic and cardiovascular diseases. In this cross-sectional study, we explored and compared the metabolic profiles of 1010 night shift workers and 1010 age- and sex-matched day workers (non-shift workers) from the Lifelines Cohort Study. The metabolic profiles were determined using the ¹H-NMR Nightingale platform for the quantification of 250 parameters of metabolism, including routine lipids, extensive lipoprotein subclasses, fatty acid composition, and various low-molecular metabolites, including amino acids, ketone bodies, and gluconeogenesis-related metabolites. Night shift workers had an increased BMI (26.6 vs. 25.9 kg/m²) compared with day workers (non-shift workers) in both sexes, were slightly more likely to be ever smokers (only in males) (54% vs. 46%), worked on average 5.9 ± 3.7 night shifts per month, and had been working in night shifts for 18.3 ± 10.5 years on average. We observed changes in several metabolic markers in male night shift workers compared with non-shift workers, but no changes were observed in women. In men, we observed higher levels of glycoprotein acetyls (GlycA), triglycerides, and fatty acids compared with non-shift workers. The changes were seen in the ratio of triglycerides and cholesterol(esters) to total lipids in different sizes of VLDL particles. Glycoprotein acetyls (GlycAs) are of particular interest as markers since they are known as biomarkers for low-grade chronic inflammation. When the analyses were adjusted for BMI, no significant associations were observed. Further studies are needed to better understand the relationship between night shift work and metabolic profiles, particularly with respect to the role of sex and BMI in this relationship.

When the clock ticks wrong with COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a member of the coronavirus family that causes the novel coronavirus disease first diagnosed in 2019 (COVID-19). Although many studies have been carried out in recent months to determine why the disease clinical presentations and outcomes can vary significantly from asymptomatic to severe or lethal, the underlying mechanisms are not fully understood. It is likely that unique individual characteristics can strongly influence the broad disease variability; thus, tailored diagnostic and therapeutic approaches are needed to improve clinical outcomes. The circadian clock is a critical regulatory mechanism orchestrating major physiological and pathological processes. It is generally accepted that more than half of the cell-specific genes in any given organ are under circadian control. Although it is known that a specific role of the circadian clock is to coordinate the immune system's steady-state function and response to infectious threats, the links between the circadian clock and SARS-CoV-2 infection are only now emerging. How inter-individual variability of the circadian profile and its dysregulation may play a role in the differences noted in the COVID-19-related disease presentations, and outcome remains largely underinvestigated. This review summarizes the current evidence on the potential links between circadian clock dysregulation and SARS-CoV-2 infection susceptibility, disease presentation and progression, and clinical outcomes. Further research in this area may contribute towards novel circadian-centred prognostic, diagnostic and therapeutic approaches for COVID-19 in the era of precision health.

Circadian Disruption and Consequences on Innate Immunity and Inflammatory Response

Circadian rhythms control almost all aspects of physiology and behavior, allowing temporal synchrony of these processes between each other, as well as with the external environment. In the immune system, daily rhythms of leukocyte functions can determine the strength of the immune response, thereby regulating the efficiency of defense mechanisms to cope with infections or tissue injury. The natural light/dark cycle is the prominent synchronizing agent perceived by the circadian clock, but this role of light is highly compromised by irregular working schedules and unintentional exposure to artificial light at night (ALAN). The primary concern is disrupted circadian control of important physiological processes, underlying potential links to adverse health effects. Here, we first discuss the immune consequences of genetic circadian disruption induced by mutation or deletion of specific clock genes. Next, we evaluate experimental research into the effects of disruptive light/dark regimes, particularly light-phase shifts, dim ALAN, and constant light on the innate immune mechanisms under steady state and acute inflammation, and in the pathogenesis of common lifestyle diseases. We suggest that a better understanding of the mechanisms by which circadian disruption influences immune status can be of importance in the search for strategies to minimize the negative consequences of chronodisruption on health.

Sleep in the intensive care unit

PURPOSE OF REVIEW

Sleep is particularly important for critically ill patients. Here, we review the latest evidence on how sleep and circadian disruption in the intensive care unit (ICU) affects physiology and clinical outcomes, as well as the most recent advances in sleep and circadian rhythm promoting interventions including therapeutics.

RECENT FINDINGS

On a molecular level, clock genes dysrhythmia and altered immunity are clearly linked, particularly in sepsis. Melatonin may also be associated with insulin sensitivity in ICU patients. Clinically, changes in sleep architecture are associated with delirium, and sleep-promoting interventions in the form of multifaceted care bundles may reduce its incidence. Regarding medications, one recent randomized controlled trial (RCT) on melatonin showed no difference in sleep quality or incidence of delirium.

SUMMARY

Further investigation is needed to establish the clinical relevance of sleep and circadian disruption in the ICU. For interventions, standardized protocols of sleep promotion bundles require validation by larger multicenter trials. Administratively, such protocols should be individualized to both organizational and independent patient needs. Incorporating pharmacotherapy such as melatonin and nocturnal dexmedetomidine requires further evaluation in large RCTs.

Role of Omega-3 Fatty Acids as Non-Photic Zeitgebers and Circadian Clock Synchronizers

Omega-3 fatty acids (ω-3 FAs) are well-known for their actions on immune/inflammatory and neurological pathways, functions that are also under circadian clock regulation. The daily photoperiod represents the primary circadian synchronizer (‘zeitgeber’), although diverse studies have pointed towards an influence of dietary FAs on the biological clock. A comprehensive literature review was conducted following predefined selection criteria with the aim of updating the evidence on the molecular mechanisms behind circadian rhythm regulation by ω-3 FAs. We collected preclinical and clinical studies, systematic reviews, and metanalyses focused on the effect of ω-3 FAs on circadian rhythms. Twenty animal (conducted on rodents and piglets) and human trials and one observational study providing evidence on the regulation of neurological, inflammatory/immune, metabolic, reproductive, cardiovascular, and biochemical processes by ω-3 FAs via clock genes were discussed. The evidence suggests that ω-3 FAs may serve as non-photic zeitgebers and prove therapeutically beneficial for circadian disruption-related pathologies. Future work should focus on the role of clock genes as a target for the therapeutic use of ω-3 FAs in inflammatory and neurological disorders, as well as on the bidirectional association between the molecular clock and ω-3 FAs.

Investigation of Possible Factors Influencing the Neutralizing Anti-SARS-CoV-2 Antibody Titer after Six Months from the Second Vaccination Dose in a Sample of Italian Nursing Home Personnel

The titer of the anti-SARS-CoV-2 antibodies produced after vaccination shows a relevant decay over time, as demonstrated in several studies. However, less is known on the possible factors affecting the entity of this decay. The aim of this study is to analyze a group of individual factors which are possibly associated with anti-SARS-CoV-2 antibody titer decay six months after the second vaccine dose. We report here the results of a follow-up serological analysis and a questionnaire-based evaluation of a sample of workers from an Italian nursing home, vaccinated with two doses of BNT162b2 vaccine in early 2021. The baseline data were collected one month after the vaccine, while in the present analysis we report the data collected six months later. Our data show a relevant decay of the neutralizing antibody titer, even if for all the workers a largely positive response was detected. Moreover, our results demonstrate a possible association between younger age and the absence of previous COVID-19 infection, and a higher decay rate of the anti-SARS-CoV-2 antibodies titer.

Immune disruptions and night shift work in hospital healthcare professionals: The intricate effects of social jet-lag and sleep debt

Objectives

We aimed to examine the effects of circadian and sleep rhythm disruptions on immune biomarkers among hospital healthcare professionals working night shifts and rotating day shifts.

Methods

Hospital nurses working either as permanent night shifters (n=95) or as day shifters rotating between morning and afternoon shifts (n=96) kept a daily diary on their sleep and work schedules over a full working week. Blood samples were collected at the beginning and end of the last shift during the week, and participants were categorized into three groups based on work shift: morning shift (39 day shifters sampled at 7:00 and 14:00), afternoon shift (57 day shifters sampled at 14:00 and 21:00), and night shift (95 night shifters sampled at 21:00 and 7:00). Circulating blood counts in immune cells, interleukin-6 and C-reactive protein concentrations as well as total sleep time per 24 hours during work days (TST24w) and free days (TST24f), sleep debt (TST24f - TST24w) and social jet-lag (a behavioral proxy of circadian misalignment) were assessed.

Results

Compared with day shifters, night shifters had shorter sleep duration (TST24w=5.4 ± 1.4h), greater sleep debt (3.2 ± 1.4 h) and social jet-lag (6.7 ± 2.4 h). Variations of immune biomarkers concentrations were consistent with the expected diurnal variations among day shifters (i.e., low level in the morning, increase during the day, peak value in the evening). By contrast, in night shifters, blood concentrations of total lymphocytes, T-helper cells, cytotoxic T-cells, memory B-cells and interleukin-6 were lower at 21:00, increased during the night, and reached higher values at 7:00. Multivariate analyses ruled out significant impact of TST24w, sleep debt, and social jet-lag on immune biomarkers concentrations among day shifters. In contrast, among night shifters, multivariate analyses indicated a combined effect of total sleep time (TST24w), sleep debt and social jet-lag for total lymphocytes and T-helper cells but only a social jet-lag effect for interleukin-6 and a single total sleep time effect for neutrophil and B-Cells.

Conclusions

Altogether, our results point to intricate response patterns of immune rhythms to circadian misalignment and sleep debt in night shifters. Specifically, these altered pattern expressions of immune cells may increase vulnerability to infections and reduce vaccination efficiency in night workers.

Night-shift work is associated with increased susceptibility to SARS-CoV-2 infection

Night-shift workers experience disturbances of their circadian rhythm and sleep, which may make them more susceptible to infectious diseases. Therefore, we studied whether night-shift workers are at higher risk of testing positive for SARS-CoV-2 infection than day workers. In this prospective study, data were used from 20 questionnaire rounds of the Dutch Lifelines COVID-19 cohort that was initiated in March 2020. In the different questionnaire rounds, 2285 night-shift workers and 23,766 day workers reported whether they had tested positive for SARS-CoV-2. Cox proportional hazards regression models adjusted for demographic, work, and health covariates were used to compare SARS-CoV-2 incidence between night-shift and day workers. From March 2020-January 2021, 3.4% of night-shift workers and 2.2% of day workers reported to have tested positive for SARS-CoV-2 (p < .001). After adjustment for covariates, night-shift workers had a 37% higher risk of testing positive for SARS-CoV-2 (hazard ratio: 1.37, 95% confidence interval: 1.05-1.77). In this study, we show that night-shift workers were more likely to test positive for SARS-CoV-2 than day workers, which adds to the growing evidence that night-shift work may influence the complex processes involved in infection susceptibility. Further mechanistic insight is needed to understand the relation between night-shift work and (SARS-CoV-2) infection susceptibility.

Study design of PerfectFit@Night, a workplace health promotion program to improve sleep, fatigue, and recovery of night shift workers in the healthcare sector

Background

Healthcare workers need to be at work 24 h a day to ensure continuity of care in hospitals. However, shift work - particularly night shifts - can have negative acute and long-term effects on health and productivity due to disturbances in the circadian rhythm. Shift work is also associated with unhealthy lifestyle behaviors such as poor sleep hygiene and diet. The PerfectFit@Night intervention aims to improve sleep and recovery, and reduce fatigue, and therewith contribute to sustainable employability of healthcare workers. The current study describes the intervention and the evaluation and implementation.

Methods

The study population will consist of healthcare workers, nurses and physicians, with night shifts in a large Dutch academic hospital. The intervention consists of individual and environmental intervention elements: i) an e-learning for healthcare workers to increase knowledge and awareness on a healthy lifestyle during night shifts, ii) a powernap bed to take powernaps during night shifts, iii) the availability of healthy food at the department during night shifts, iv) a workshop on healthy rostering at the level of the department, and v) individual sleep coaching among the high risk group. In a longitudinal prospective study, data will be collected 1 month before the start of the intervention, in the week before the start of the intervention, and three and 6 months after the start of the intervention. The primary outcomes are sleep, fatigue, and need for recovery. The implementation process will be evaluated using the framework of Steckler and Linnan. Cost-benefit analyses from the employers perspective will be conducted to understand the possible financial consequences or benefits of the implementation of PerfectFit@Night.

Discussion

The feasibility and effectiveness of this workplace health promotion program will be investigated by means of an effect, process and economic evaluation. If proven effective, PerfectFit@Night can be implemented on a larger scale within the healthcare sector.

Trial registration

Netherlands Trial Register trial number NL9224. Registered 17 January 2021.

Characteristics and Determinants of the Presence of Respiratory Symptoms among Sewage Workers in Malaysia

Background

The purpose of this study was to determine the relationships of PM 2.5 and H₂S exposure with the presence of work-related respiratory symptoms among sewage workers.

Methods

A cross-sectional study was conducted in eleven sewage plants located in the central region of Peninsular Malaysia. One hundred ninety-one sewage workers were assessed using the British Medical Research Council (BMRC) questionnaire. Area air sampling was performed in three different sewage plants to measure the following parameters: physical air quality and concentration of PM 2.5 and H₂S.

Result

Chronic cough (34.0%) was reported as the most common symptom, followed by chronic phlegm (26.2%), shortness of breath (7.9%), and chest tightness (3.7%). There were five significant determinants of the presence of respiratory symptoms among the sewage workers: shift work (AOR 23.50, 95% CI: 1.90–616.52), working at a sludge treatment facility (STF) (AOR 25.46, 95% CI: 2.06–314.29), a longer duration of working years (AOR 1,21, 95% CI: 1.01–1.44), individual cumulative exposure to PM 2.5 (AOR 9.01, 95% CI: 1.98–83.33), and individual cumulative exposure to H₂S (AOR 1.04, 95% CI: 1.01–1.07). The majority of STF and non-STF workers had higher exposure to PM 2.5 and H₂S concentrations in the air than office workers.

Conclusion

Sewage workers working at non-STFs or STFs reported a significantly higher prevalence of work-related respiratory symptoms and exposure to PM 2.5 and H₂S compared with office workers. Exposure-response relationships were also found in sewage workers' cumulative exposure to PM 2.5 and H₂S and the presence of respiratory symptoms.

Circadian regulation of innate immunity in animals and humans and implications for human disease

Circadian rhythms are 24-h oscillating variations in physiology generated by the core circadian clock. There is now a wide body of evidence showing circadian regulation of the immune system. Innate immune cells contain the molecular circadian clock which drives rhythmic responses, from the magnitude of the inflammatory response to the numbers of circulating immune cells varying throughout the day. This leads to rhythmic presentation of disease clinically, for example the classic presentation of nocturnal asthma or the sudden development of pulmonary oedema from acute myocardial infarction first thing in the morning.

Macrophage Meets the Circadian Clock: Implication of the Circadian Clock in the Role of Macrophages in Acute Lower Respiratory Tract Infection

The circadian rhythm is a biological system that creates daily variations of physiology and behavior with a 24-h cycle, which is precisely controlled by the molecular circadian clock. The circadian clock dominates temporal activity of physiological homeostasis at the molecular level, including endocrine secretion, metabolic, immune response, coupled with extrinsic environmental cues (e.g., light/dark cycles) and behavioral cues (e.g., sleep/wake cycles and feeding/fasting cycles). The other side of the clock is that the misaligned circadian rhythm contributes to the onset of a variety of diseases, such as cancer, metabolic diseases, and cardiovascular diseases, the acceleration of aging, and the development of systemic inflammation. The role played by macrophages is a key mediator between circadian disruption and systemic inflammation. At the molecular level, macrophage functions are under the direct control of the circadian clock, and thus the circadian misalignment remodels the phenotype of macrophages toward a ‘killer’ mode. Remarkably, the inflammatory macrophages induce systemic and chronic inflammation, leading to the development of inflammatory diseases and the dampened immune defensive machinery against infectious diseases such as COVID-19. Here, we discuss how the circadian clock regulates macrophage immune functions and provide the potential risk of misaligned circadian rhythms against inflammatory and infectious diseases.

Night shift work characteristics are associated with several elevated metabolic risk factors and immune cell counts in a cross-sectional study

Night shift work is associated with increased health risks. Here we examined the association of metabolic risk factors and immune cell counts, with both night shift work and particular characteristics thereof: frequency, duration and consecutive night shifts. We performed a cross-sectional study using data from 10,201 non-shift workers and 1062 night shift workers of the Lifelines Cohort study. Linear regression analyses, adjusted for demographic, lifestyle and occupational factors, were used to study associations of night shift work characteristics with metabolic risk factors and immune cell counts. Night shift workers had an increased BMI, waist circumference and immune cell counts compared to non-shift workers. This was especially seen in night shift workers who had a higher frequency of night shifts per month (≥ 5: BMI: B = 0.81 kg/m² (95%-CI = 0.43–1.10); waist circumference: B = 1.58 cm (95%-Cl = 0.34–1.71; leukocytes: B = 0.19 × 10⁹ cells/L (95%-CI = 0.04–0.34 × 10⁹)) and worked more consecutive night shifts (> 3: BMI: B = 0.92 kg/m² (95%-CI = 0.41–1.43); waist circumference: B = 1.85 cm (95%-Cl = 0.45–3.24); leukocytes: B = 0.32 × 10⁹ cells/L (95%-CI = 0.09–0.55 × 10⁹)). This association was less pronounced in long-term night shift workers (≥ 20 years). Our findings provide evidence for the association between night shift work characteristics and BMI, waist circumference and leukocytes (including, monocytes, lymphocytes, and basophil granulocytes).

Potential effects of shift work on skin autoimmune diseases

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

Shift Work Predicts Increases in Lipopolysaccharide-Binding Protein, Interleukin-10, and Leukocyte Counts in a Cross-Sectional Study of Healthy Volunteers Carrying Low-Grade Systemic Inflammation

The disruption of inflammatory responses is a potential mechanism behind the harmful effects of shift work and is associated with increased risk of hypertension, stroke, obesity, diabetes, and cancer. These responses are linked to the proliferation of leukocytes in shift workers, suggesting a systemic signal as a potential mediator. The purpose of this study was to assess the relationship between systemic inflammation, leukocyte counts, and systemic endotoxemia in samples from a diverse cohort of day workers and shift workers. Participants (normothermic and normotensive) were healthy volunteers, non-smoking, and drug- and medication-free. The following outcomes were measured: C-reactive protein, TNF-α, IL-6, IL-1β, IL-10, leukocyte counts (monocytes, lymphocytes, and neutrophils), and lipopolysaccharide-binding protein (LBP). Risk factors that increase systemic inflammation, such as blood pressure, sleep loss, and cortisol, were also assessed. The results indicated that shift workers slept significantly less than day workers and had significantly increased concentrations of all of the cytokines measured as well as plasma cortisol. Regression models found that after controlling for covariates, shift-work exposure predicted the significant increase observed in IL-10, leukocyte counts, and LBP. Our results suggest that acute increases in low-grade systemic endotoxemia are unresolved during chronic shift-work exposure. This ongoing immune challenge may underlie the disrupted inflammatory responses characteristic of shift-work-related pathologies. Systemic endotoxemia may represent a novel target to investigate the early effects of exposure to shift-work schedules.

COVID-19, circadian rhythms and sleep: from virology to chronobiology

Various aspects of our physiology and immune response to pathogens are under 24 h circadian control and its role in clinical and research practice is becoming increasingly recognized. Severe acute respiratory syndrome coronavirus-2, the causative agent of Coronavirus disease 2019 (COVID-19) has affected millions of people to date. Cross-disciplinary approaches and collaborative efforts have led to an unprecedented speed in developing novel therapies and vaccines to tackle the COVID-19 pandemic. Circadian misalignment and sleep disruption have a profound impact on immune function and subsequently on the ability of individuals to combat infections. This review summarizes the evidence on the interplay between circadian biology, sleep and COVID-19 with the aim to identify areas of translational potentials that may inform diagnostic and therapeutic strategies in this pandemic.

Factors Associated with SARS-CoV-2 Infection Risk among Healthcare Workers of an Italian University Hospital

We report the results of a study on the cumulative incidence of SARS-CoV-2 infections in about 6000 workers of the University Hospital of Modena, Northern Italy, in the period March 2020–January 2021, and the relations with some individual and occupational factors. Overall, in healthcare workers (HCW) the cumulative incidence of COVID-19 during the period was 13.8%. Results confirm the role of overweight and obesity as significant risk factors for SARS-CoV-2 infection. Chronic respiratory diseases, including asthma, also proved to be significantly associated with the infection rate. Considering occupational factors, the COVID-19 risk was about threefold (OR: 2.7; 95% CI 1.7–4.5) greater in nurses and nurse aides than in non-HCW, and about double (OR: 1.9; 95% CI 1.2–3.2) in physicians. Interestingly, an association was also observed between infection risk and nightshifts at work (OR: 1.8; 95% CI 1.4–2.3), significantly related to the total number of shifts in the whole eleven-month period. Even if the vaccination campaign has now greatly modified the scenario of SARS-CoV-2 infections among HCW, the results of this study can be useful for further development of health and policy strategies to mitigate the occupational risk related to the new variants of coronavirus, and therefore the evolution of the pandemic.

Hospitalized COVID-19 Patients Were Five Times More Likely to Suffer From Total Sleep Deprivation Compared to Non-COVID-19 Patients; an Observational Comparative Study

Objectives: Sleeping disorders are a common complaint in patients who suffer from an acute COVID-19 infection. Nonetheless, little is known about the severity of sleep disturbances in hospitalized COVID-19 patients, and whether these are caused by disease related symptoms, hospitalization, or the SARS-CoV-2 virus itself. Therefore, the aim of this study was to compare the quality and quantity of sleep in hospitalized patients with and without COVID-19, and to determine the main reasons for sleep disruption. Methods: This was an observational comparative study conducted between October 1, 2020 and February 1, 2021 at the pulmonary ward of an academic hospital in the Netherlands. This ward contained both COVID-19-positive and -negative tested patients. The sleep quality was assessed using the PROMIS-Sleep Disturbance Short Form and sleep quantity using the Consensus Sleep Diary. Patient-reported sleep disturbing factors were summarized. Results: A total of 79 COVID-19 patients (mean age 63.0, male 59.5%) and 50 non-COVID-19 patients (mean age 59.5, male 54.0%) participated in this study. A significantly larger proportion of patients with COVID-19 reported not to have slept at all (19% vs. 4% of non-COVID-19 patients, p = 0.011). The Sleep quality (PROMIS total score) and quantity (Total Sleep Time) did not significantly differ between both groups ((median PROMIS total score COVID-19; 26 [IQR 17-35], non-COVID-19; 23 [IQR 18-29], p = 0.104), (Mean Total Sleep Time COVID-19; 5 h 5 min, non-COVID-19 mean; 5 h 32 min, p = 0.405)). The most frequently reported disturbing factors by COVID-19 patients were; 'dyspnea', 'concerns about the disease', 'anxiety' and 'noises of other patients, medical staff and medical devices'. Conclusion: This study showed that both patients with and without an acute COVID-19 infection experienced poor quality and quantity of sleep at the hospital. Although the mean scores did not significantly differ between groups, total sleep deprivation was reported five times more often by COVID-19 patients. With one in five COVID-19 patients reporting a complete absence of night sleep, poor sleep seems to be a serious problem. Sleep improving interventions should focus on physical and psychological comfort and noise reduction in the hospital environment.

Comparison of Psychological and Physiological Stress in NICU Nurses: Effects of Unit Design and Shift

BACKGROUND

Effects of unit design and shift worked on stress in neonatal intensive care unit (NICU) nurses have not been fully studied.

PURPOSE

To compare stress in NICU nurses who work in single-family room (SFR) or open bay (OBY) units and on nonrotating day or night shift.

METHODS

Full-time registered nurses (RNs) (n = 72) from a 42-bed SFR and a 131-bed OBY NICU participated in this comparative cross-sectional study. The Nurse Stress Scale (NSS) and within-shift repeated salivary cortisol levels were used to measure stress. The relationship between NSS score and salivary cortisol level was examined using multiple linear regression. Salivary cortisol levels of day versus night shift were compared with mixed-effects linear models.

RESULTS

NSS scores were similar for SFR and OBY units (P = .672) and day versus night shift (P = .606). Changes in cortisol level over time (P = .764) and final cortisol level (P = .883) for SFR versus OBY were not significantly different after controlling for shift. Salivary cortisol level of day-shift nurses decreased significantly over time compared with night-shift nurses (P < .001). The final cortisol level was significantly higher for night-shift compared with day-shift nurses (P < .001).

IMPLICATIONS FOR PRACTICE

Psychological (NSS) and physiologic (salivary cortisol) stress of NICU nurses is similar in established SFR and OBY units. Cortisol levels are higher at the end of shift in nurses who work night shift and may reflect increased physiologic stress.

IMPLICATIONS FOR RESEARCH

Strategies are needed for reducing stress in NICU nurses who work night shift.

Associations between sleep duration, shift work, and infectious illness in the United States: Data from the National Health Interview Survey

OBJECTIVE

Insufficient sleep and circadian disruption have been linked to immune system dysregulation. The aim of this study was to examine the associations between self-reported sleep duration and work schedule with reports of head and chest colds among adults 18 years and older in the United States.

METHODS

Associations between self-reported habitual sleep duration and work schedule (regular daytime, regular evening, regular nighttime, rotating, other) with reports head and chest colds in the past 2 weeks were examined using data from the 2010 and 2015 National Health Interview Survey. Adults who slept 7-8 hours or reported a regular daytime work schedule were considered the reference group. Multivariate logistic regressions, incorporating sampling weights, were computed adjusting for sociodemographic and health characteristics.

RESULTS

Analyses revealed in fully adjusted models that compared to 7- 8 hours sleepers, those sleeping 5 or fewer hours were 44% more likely to report a cold (odds ratio [OR] = 1.44, 95% confidence interval [CI] 1.29-1.61) while those sleeping 9 or more hours were 20% more likely (OR = 1.20, 95% CI 1.06-1.36). Participants who reported a rotating work schedule were 20% more likely to report a cold (OR = 1.20, 95% CI 1.07-1.36) than those reporting a regular daytime work schedule.

CONCLUSIONS

Short and long sleep duration, as well as a rotating shift work schedule, were associated with increased reports of head and chest colds in a nationally representative sample of US adults. Sleep and circadian function may serve as relevant targets to reduce susceptibility to infectious illness.

Shift work is associated with positive COVID-19 status in hospitalised patients

INTRODUCTION

Shift work is associated with lung disease and infections. We therefore investigated the impact of shift work on significant COVID-19 illness.

METHODS

501 000 UK Biobank participants were linked to secondary care SARS-CoV-2 PCR results from Public Health England. Healthcare worker occupational testing and those without an occupational history were excluded from analysis.

RESULTS

Multivariate logistic regression (age, sex, ethnicity and deprivation index) revealed that irregular shift work (OR 2.42, 95% CI 1.92 to 3.05), permanent shift work (OR 2.5, 95% CI 1.95 to 3.19), day shift work (OR 2.01, 95% CI 1.55 to 2.6), irregular night shift work (OR 3.04, 95% CI 2.37 to 3.9) and permanent night shift work (OR 2.49, 95% CI 1.67 to 3.7) were all associated with positive COVID-19 tests compared with participants that did not perform shift work. This relationship persisted after adding sleep duration, chronotype, premorbid disease, body mass index, alcohol and smoking to the model. The effects of workplace were controlled for in three ways: (1) by adding in work factors (proximity to a colleague combined with estimated disease exposure) to the multivariate model or (2) comparing participants within each job sector (non-essential, essential and healthcare) and (3) comparing shift work and non-shift working colleagues. In all cases, shift work was significantly associated with COVID-19. In 2017, 120 307 UK Biobank participants had their occupational history reprofiled. Using this updated occupational data shift work remained associated with COVID-19 (OR 4.48 (95% CI 1.8 to 11.18).

CONCLUSIONS

Shift work is associated with a higher likelihood of in-hospital COVID-19 positivity. This risk could potentially be mitigated via additional workplace precautions or vaccination.

Very-Short-Term Sleep Deprivation Slows Early Recovery of Lymphocytes in Septic Patients

Sleep plays an important role in immune function. However, the effects of very-short-term sleep deprivation on the early recovery of immune function after sepsis remain unclear. This study was conducted in the intensive care unit to investigate the effects of 2 consecutive days of sleep deprivation (SD) on lymphocyte recovery over the following few days in septic patients who were recovering from a critical illness. The patients' self-reports of sleep quality was assessed using the Richards–Campbell Sleep Questionnaire at 0 and 24 h after inclusion. The demographic, clinical, laboratory, treatment, and outcome data were collected and compared between the good sleep group and poor sleep group. We found that 2 consecutive days of SD decreased the absolute lymphocyte count (ALC) and ALC recovery at 3 days after SD. Furthermore, post-septic poor sleep decreased the plasma levels of atrial natriuretic peptide (ANP) immediately after 2 consecutive days of SD. The ANP levels at 24 h after inclusion were positively correlated with ALC recovery, the number of CD3⁺ T cells, or the number of CD3⁺ CD4⁺ cells in the peripheral blood on day 5 after inclusion. Our data suggested that very-short-term poor sleep quality could slow down lymphocyte recovery over the following few days in septic patients who were recovering from a critical illness. Our results underscore the significance of very-short-term SD on serious negative effects on the immune function. Therefore, it is suggested that continuous SD or several short-term SD with short intervals should be avoided in septic patients.

Light Environment Influences Developmental Programming of the Metabolic and Visual Systems in Mice

Purpose

Light is a salient cue that can influence neurodevelopment and the immune system. Light exposure out of sync with the endogenous clock causes circadian disruption and chronic disease. Environmental light exposure may contribute to developmental programming of metabolic and neurological systems but has been largely overlooked in Developmental Origins of Health and Disease (DOHaD) research. Here, we investigated whether developmental light exposure altered programming of visual and metabolic systems.

Methods

Pregnant mice and pups were exposed to control light (12:12 light:dark) or weekly light cycle inversions (circadian disruption [CD]) until weaning, after which male and female offspring were housed in control light and longitudinally measured to evaluate differences in growth (weight), glucose tolerance, visual function (optomotor response), and retinal function (electroretinogram), with and without high fat diet (HFD) challenge. Retinal microglia and macrophages were quantified by positive Iba1 and CD11b immunofluorescence.

Results

CD exposure caused impaired visual function and increased retinal immune cell expression in adult offspring. When challenged with HFD, CD offspring also exhibited altered retinal function and sex-specific impairments in glucose tolerance.

Conclusions

Overall, these findings suggest that the light environment contributes to developmental programming of the metabolic and visual systems, potentially promoting a pro-inflammatory milieu in the retina and increasing the risk of visual disease later in life.

The role of circadian rhythm stability and amplitude in musculoskeletal disorder prevalence and work-family conflict

Aim

This study aimed to investigate the effect of circadian rhythm stability and amplitude on musculoskeletal disorder prevalence and work–family conflict among nurses.

Design

This cross‐sectional study was conducted on 386 nurses working in three hospitals, in Shahroud, Iran.

Method

The data were collected using the Circadian Rhythm Inventory, Nordic Musculoskeletal Disorders, and Carlson Work‐Family Conflict questionnaires.

Results

The highest prevalence of musculoskeletal disorders was reported in the lower back (68.4%), upper back (65.5%) and shoulders (53.6%), respectively. No significant relation was found between circadian rhythm stability and amplitude, and musculoskeletal disorders prevalence. The nurses who could not overcome drowsiness reported more Work Interference with Family (WIF), Family Interference with Work (FIW) (time‐based) and FIW (strain‐based) compared to the nurses who overcame drowsiness. In addition, the appropriate nurses for shift work experienced less WIF, FIW (behavioural‐based) and WIF (strain‐based) compared to the nurses who could not work overtime or at night.

Shifted Firefighter Health Investigation by Personal Health Insurance Record in Taiwan

INTRODUCTION

Taiwan's firefighters use a shift rotation system with 2 days of work and 1 day of rest. Numerous papers have already explored the risks of shift work to the body. However, little data concern the impact of shift work on health as reflected in medical visits. This study used individuals' medical visit record in Taiwan's health insurance system. The locally called "health bank" contains individuals' medical visit record, health insurance payment points and the medicine used.

METHODS

Consent was obtained from 150 firefighters who were serving under the shift rotation system to obtain their 2015 individual "My Health Bank" medical data. Comparisons were made between national health insurance data norm.

RESULTS

Firefighters make significantly more visits for Western medicine than the annual average (firefighters 6.27 vs norm 5.24, P = 0.04142), more total number of medical visits (9.57 vs 7.75, P = 0.0102), more annual average payment points for Western medicine (4079 vs 2741, P = 0.003151), and a greater average number of total annual medical visit points (7003 vs 4940, p = 0.0003157). Firefighters had significantly higher incidents of respiratory diseases, urogenital diseases, skin and subcutaneous tissue diseases, musculoskeletal system and connective tissue diseases, injuries, and illness from poisoning than did the norm (P<0.05).

CONCLUSION

A persuasive health-survey-based method for workers in high occupational hazard industries was proposed in this study, and the result was highly correlated with risk factors of fireworkers. The proposed study method is potential to investigate risk factors of other working.

Sickness absenteeism, work performance, and healthcare use due to respiratory infections for shift and non-shift workers

This study aimed to compare sickness absenteeism, work performance, and healthcare use due to respiratory infections, as well as general sickness absenteeism and work performance between shift and non-shift workers. In this study, 589 shift and non-shift workers employed in hospitals were included. For 6 months, participants kept a daily record of their influenza-like illness/acute respiratory infection (ILI/ARI) symptoms using a diary application. After an episode of ILI/ARI symptoms ended, participants (n = 531) were questioned about their sickness absenteeism (occurrence and duration in hours), work performance (on a 10 point scale), and healthcare use during the ILI/ARI episode. At the end of the 6 months follow-up, participants (n = 498) were also asked about general sickness absenteeism and work performance in the past 4 weeks. Mixed-model and regression analyses were used to compare absenteeism, work performance, and healthcare use between shift and non-shift workers. No differences were found in sickness absenteeism [Odds Ratio (OR) = 1.00 (95%‒Confidence Interval (CI): 0.61‒1.64)] and work performance [Regression coefficient (B) = -0.19 (95%‒CI: -0.65‒0.26)] due to ILI/ARI between shift and non-shift workers. In addition, healthcare use due to ILI/ARI was similar between shift and non-shift workers. Furthermore, similar general sickness absenteeism rates and work performance levels were found between shift and non-shift workers. As this is the first study that examined the associations with shift work due to ILI/ARI, further studies are needed to confirm our findings.

Shift work influences the outcomes of Chlamydia infection and pathogenesis

Shift work, performed by approximately 21 million Americans, is irregular or unusual work schedule hours occurring after 6:00 pm. Shift work has been shown to disrupt circadian rhythms and is associated with several adverse health outcomes and chronic diseases such as cancer, gastrointestinal and psychiatric diseases and disorders. It is unclear if shift work influences the complications associated with certain infectious agents, such as pelvic inflammatory disease, ectopic pregnancy and tubal factor infertility resulting from genital chlamydial infection. We used an Environmental circadian disruption (ECD) model mimicking circadian disruption occurring during shift work, where mice had a 6-h advance in the normal light/dark cycle (LD) every week for a month. Control group mice were housed under normal 12/12 LD cycle. Our hypothesis was that compared to controls, mice that had their circadian rhythms disrupted in this ECD model will have a higher Chlamydia load, more pathology and decreased fertility rate following Chlamydia infection. Results showed that, compared to controls, mice that had their circadian rhythms disrupted (ECD) had higher Chlamydia loads, more tissue alterations or lesions, and lower fertility rate associated with chlamydial infection. Also, infected ECD mice elicited higher proinflammatory cytokines compared to mice under normal 12/12 LD cycle. These results imply that there might be an association between shift work and the increased likelihood of developing more severe disease from Chlamydia infection.

Poor-sleep is associated with slow recovery from lymphopenia and an increased need for ICU care in hospitalized patients with COVID-19: A retrospective cohort study

Sleep is known to play an important role in immune function. However, the effects of sleep quality during hospitalization for COVID-19 remain unclear. This retrospective, single-center cohort study was conducted to investigate the effects of sleep quality on recovery from lymphopenia and clinical outcomes in hospitalized patients with laboratory-confirmed COVID-19 admitted to the West District of Wuhan Union Hospital between January 25 and March 15, 2020. The Richards-Campbell sleep questionnaire (RCSQ) and Pittsburgh Sleep Quality Index (PSQI) were used to assess sleep quality. The epidemiological, demographic, clinical, laboratory, treatment, and outcome data were collected from electronic medical records and compared between the good-sleep group and poor-sleep group. In all, 135 patients (60 in good-sleep group and 75 in poor-sleep group) were included in this study. There were no significant between-group differences regarding demographic and baseline characteristics, as well as laboratory parameters upon admission and in-hospital treatment. Compared with patients in the good-sleep group, patients in the poor-sleep group had lower absolute lymphocyte count (ALC) (day 14: median, 1.10 vs 1.32, P = 0.0055; day 21: median, 1.18 vs 1.48, P = 0.0034) and its reduced recovery rate (day 14: median, 56.91 vs 69.40, P = 0.0255; day 21: median, 61.40 vs 111.47, P = 0.0003), as well as increased neutrophil-to-lymphocyte ratio (NLR; day 14: median, 3.17 vs 2.44, P = 0.0284; day 21: median, 2.73 vs 2.23, P = 0.0092) and its associated deterioration rate (day 14: median, -39.65 vs -61.09, P = 0.0155; day 21: median, -51.40% vs -75.43, P = 0.0003). Nine [12.0%] patients in the poor-sleep group required ICU care (P = 0.0151); meanwhile, none of the patients in good-sleep group required ICU care. Patients in the poor-sleep group had increased duration of hospital stay (33.0 [23.0-47.0] days vs 25.0 [20.5-36.5] days, P = 0.0116) compared to those in the good-sleep group. An increased incidence of hospital-acquired infection (seven [9.3%] vs one [1.7%]) was observed in the poor-sleep group compared to the good-sleep group; however, this difference was not significant (P = 0.1316). In conclusion, poor sleep quality during hospitalization in COVID-19 patients with lymphopenia is associated with a slow recovery from lymphopenia and an increased need for ICU care.

The mediating role of sleep, physical activity, and diet in the association between shift work and respiratory infections

Objectives:

Shift work may be associated with an increased incidence of respiratory infections. However, underlying mechanisms are unclear. Therefore, our aim was to examine the mediating role of sleep, physical activity, and diet in the association between shift work and respiratory infections.

Methods:

This prospective cohort study included 396 shift and non-shift workers employed in hospitals. At baseline, sleep duration and physical activity were measured using actigraphy and sleep/activity diaries, sleep quality was reported, and frequency of meal and snack consumption was measured using food diaries. In the following six months, participants used a smartphone application to report their influenza-like illness/acute respiratory infection (ILI/ARI) symptoms daily. Mediation analysis of sleep, physical activity, and diet as potential mediators of the effect of shift work on ILI/ARI incidence rate was performed using structural equation modeling with negative binomial and logistic regression.

Results:

Shift workers had a 23% [incidence rate ratio (IRR) 1.23, 95% CI 1.01–1.49] higher incidence rate of ILI/ARI than non-shift workers. After adding the potential mediators to the model, this reduced to 15% (IRR 1.15, 95% CI 0.94–1.40). The largest mediating (ie, indirect) effect was found for poor sleep quality, with shift workers having 29% more ILI/ARI episodes via the pathway of poorer sleep quality (IRR 1.29, 95% CI 1.02–1.95).

Conclusions:

Compared to non-shift workers, shift workers had a higher incidence rate of ILI/ARI that was partly mediated by poorer sleep quality. Therefore, it may be relevant for future research to focus on perceived sleep quality as an underlying mechanism in the relation between shift work and increased infection susceptibility.

Immunological effects of shift work in healthcare workers

The 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.