The relationship between night shift work, sleep patterns, psychological well-being, and mental health among Jordanian healthcare workers.

This study examines the associations between working night shifts and various outcomes, including sleep patterns, healthcare workers' sleep quality, and physical, mental, and social well-being. A descriptive cross-sectional study was conducted, where the findings revealed that night shift healthcare workers experienced poor sleep quality and pattern. In addition, night shift healthcare workers were more likely to express their intent to leave, the impact of work on their social lives, and a low level of job satisfaction. Healthcare workers showed moderate anxiety and mild depression levels. Lower job satisfaction correlated with higher anxiety and depression levels among healthcare workers, while the negative impact of working hours on social life was associated with increased anxiety and depression. Organizations should consider establishing comprehensive wellness initiatives covering work-life balance, stress management strategies, and mental health resources.

Investigation of the possible effects of night shift on telomere length and mtDNA copy number in nurses.

In this study, we aimed to investigate the impacts of altered circadian rhythm on telomere length and mtDNA copy number (mtDNA-CN) in nurses working night shifts. In our study, 52 healthy nurses working in shifts at Ondokuz Mayis University Hospital and 45 healthy control subjects working during the day were included. qRT-PCR technique was used for the determination of telomere length and mtDNA-CN. It was observed that the shift-work group had poor sleep quality (p = 0.004), feeling tired (p < 0.01) and stressed (p = 0.02) more than control group working during the day. Nurses working in shifts were found to have 1.18 times longer telomeres with respect to the control group working during the day (p = 0.005). When compared among shift workers, poor sleep quality and insufficient sleep duration shortened telomeres (r = 0.32; p = 0.02). There was no statistically significantdisparity regarding mtDNA-CN among the nurses working in shifts and the control group working during the day (p = 0.07). Insufficient sleep was associated with decreased mtDNA-CN when shift-working nurses were compared according to sleep quality (p = 0.006). Furthermore, mtDNA-CN of nurses with poor sleep quality was correlated with lower mtDNA-CN in comparison to nurses with good sleep quality (r = 0.284; p = 0.04). The mtDNA-CN of the nurses was positively associated with the sleep duration the night sleep before the night shift (r = 0.32; p = 0.02). Inadequate sleep duration and quality were observed to cause a reduction in mtDNA-CN of nurses. In conclusion, it has been observed that poor sleep quality and duration are related to shortened telomere length and decreased mtDNA-CN in night shift nurses.

Evaluation of the Impact of Night Shift Work on Disease Severity in Psoriatic Patients: A Case-Control Study with Clinical, Hormonal, and Immunological Evaluation.

INTRODUCTION: Night shift work disrupts circadian rhythms and has been associated with immune system alterations and various health conditions. However, there is limited data regarding its impact on psoriasis. The aim of our study was to compare psoriasis severity and the hormonal and immunological profile in patients with a night shift work to those with a daytime occupation. METHODS: In this case-control study, we enrolled psoriatic patients aged >18 years engaged in night shift work and a control group of psoriatic patients with a daytime occupation. A further categorization was performed by the duration of night shift work: < or ≥7 days a month and < or ≥8 years. Disease severity was evaluated by PASI, BSA, and DLQI, and blood samples were taken to measure various hormonal and immunological markers. Univariable and multivariable analysis were performed to assess differences between the two groups. RESULTS: A total of 40 night shift workers were included, along with 36 patients in the control group. Patients who worked night shifts at least 7 days a month had significantly higher PASI scores (11.2 ± 6.6 vs. 8.5 ± 6.6; p = 0.04) and higher IL-8 serum (115.33 ± 463.65 pg/mL vs. 19.98 ± 29.78 pg/mL; p = 0.006) compared to patients who did not. Night shifts workers for at least 8 years had higher BMI (28.65 ± 4.56 vs. 25.32 ± 5.50, p = 0.010), and females had higher testosterone levels (0.46 ± 0.53 ng/mL vs. 0.23 ± 0.13 ng/mL; p = 0.055). CONCLUSION: Night shift might increase psoriasis severity and have an impact on chronic inflammation, obesity, and hormonal imbalances.

Association of night-shift work with gambling and problem gambling among workers in Japan: A nationwide cross-sectional study.

BACKGROUND AND AIMS: Night-shift work disturbs sleep and is associated with poor health conditions among workers. We aimed to investigate the association between night-shift work and gambling among workers and the association between night-shift work and problem gambling in working and gambling participants. METHODS: This cross-sectional study used data from an online survey conducted between February 6 and 27, 2023 in Japan. A total of 21,134 workers participated in this study, including 9,739 respondents who had gambled in the past year. We estimated the association between night-shift work and gambling among workers and the association between night-shift work and problem gambling among those who gambled at the survey. We defined problem gambling as a score ≥ 8 on the Problem Gambling Severity Index. All estimates were weighted using a nationally representative survey in Japan. We fitted multivariable weighted logistic regression models after adjusting for 14 confounders. RESULTS: The weighted prevalence of gambling among non-night and night-shift workers was 42.1 % and 55.4 %, respectively. When focusing on workers gambling in the survey, the prevalence of problem gambling among non-night and night-shift workers was 8.8 % and 24.2 %, respectively. The weighted multivariable logistic regression analyses showed that night-shift work was associated with gambling participation among workers (adjusted odds ratio [aOR], 1.39, 95 % confidence interval [CI] 1.25-1.53, p < 0.001). In addition, night-shift work was associated with problem gambling among those who gambled (aOR 1.94, 95 % CI 1.57-2.40, p < 0.001). CONCLUSIONS: Night-shift work was associated with gambling among workers and with problem gambling among those who gambled.

Risk of prostate cancer with increasing years of night shift work: A two-stage dose-response meta-analysis with duration of night shift work as exposure dose.

Introduction: Night shift work could be a modifiable risk factor for prostate cancer. However, the epidemiological evidence is inconsistent. To summarize the existing evidence on this topic, we conducted a two-stage dose-response meta-analysis. Methods: Medical librarians searched PubMed, EMBASE, and the Cochrane Library on December 30, 2022. Seven criteria were used to determine the inclusion of each study in the present analysis. Results: Eleven cohort studies (12 cohort reports; total cases: 9366; and total person-years: 88,238,009) and seven case-control studies (seven case-control reports; total cases: 5593; and total controls: 6876) were included. This study estimated that the risk of prostate cancer increased by 1, 12, 24, and 39% after 1, 10, 20, and 30 years of night shift work exposure, respectively, according to four cohort and five case-control studies. Discussion: Seven inclusion criteria were used to determine which studies were eligible for this analysis. Risk ratios from cohort studies and odds ratios from case-control studies were analyzed separately. However, all odds ratios from the case-control studies were excluded because of a high likelihood of publication bias. Moreover, exposure, measured in years of night shift work, was defined based on the information provided by individual studies. Finally, we utilized a recently reported two-stage dose-response meta-analysis method. This study provides evidence that night shift work contributes to the risk of prostate cancer in a dose-dependent manner.

Relationship between night work and health-related quality of life: an analysis based on profiles and cumulative duration of exposure to night work among French workers in the CONSTANCES cohort.

OBJECTIVE: The aim of this study is to estimate the association between night work and health-related quality of life (HRQoL) among French workers. The association between cumulative duration of night work and HRQoL was also investigated. METHODS: Three career-long night work exposure groups were defined at inclusion in the CONSTANCES cohort: permanent night workers, rotating night workers and former night workers. Day workers with no experience of night work were the reference group. HRQoL was assessed using the Short Form Health Survey (SF-12), in particular the physical component summary (PCS) and mental component summary (MCS) scores, with a higher score indicating better HRQoL. Several linear regression models were built to test the association between night work exposure and HRQoL. The relationship between cumulative duration of night work and HRQoL scores was analyzed using generalised additive models. RESULTS: The sample consisted of 10,372 participants. Former night workers had a significantly lower PCS score than day workers (ß [95% CI]: - 1.09 [- 1.73; - 0.45], p = 0.001), whereas permanent night workers had a significantly higher MCS score (ß [95% CI]: 1.19 [0.009; 2.36], p = 0.048). A significant decrease in PCS score from 5 to 20 years of cumulative night work was observed among former night workers. CONCLUSIONS: Former night workers had poorer physical HRQoL in contrast to permanent and rotating night workers who had similar or even better HRQoL than day workers, suggesting the well-known healthy worker survivor effect. Consequently, both current and former night workers require regular and specific follow-up focused on the physical components of their health.

A 90- followed by a 30-min nap reduces fatigue whereas a 30- followed by a 90-min nap maintains cognitive performance in night work: A randomized crossover-pilot study.

OBJECTIVE: To investigate the effects of combinations of brief naps (a 90- followed by a 30-min nap vs. a 30- followed by a 90-min nap) on sleep inertia, reducing sleepiness and fatigue, and maintaining performance during night hours. METHODS: This randomized, comparative, repeated-measure, cross-over study investigated subjective and cognitive performance in 12 healthy females, evaluated in three experimental nap conditions: 1) from 22:30 to 00:00 and 02:30 to 03:00 (Pre90-NAP group), 2) from 23:30 to 00:00 and 02:30 to 04:00 (Pre30-NAP) group, and 3) no naps (NO-NAP group). Participants' body temperature, psychomotor vigilance task (PVT) and Uchida-Kraepelin test (UKT) scores, and subjective feelings of drowsiness and fatigue were evaluated. Sleep state was determined by an actigraphy monitoring device worn by participants. RESULTS: Regardless of timing, both 90-min naps were associated with sleep inertia, and both 30-min naps with minimal sleep inertia. Reaction times were shorter and fewer errors were committed at 2 h post-nap in the Pre30-NAP and Pre90-NAP groups compared with those at the same time in the NO-NAP group. Adding a 90-min nap to a 30-min nap reduced subjective fatigue and shortened reaction times, and adding a 30-min nap to a 90-min nap was effective in maintaining performance, suggesting a synergistic effect. CONCLUSIONS: Taking two naps during a night work can mitigate sleepiness and fatigue, and maintain performance. A 90- followed by a 30-min nap reduced fatigue and reaction time, and a 30- followed by a 90-min nap maintained cognitive performance in the early morning.

Night shift work, genetic risk, and the risk of depression: A prospective cohort study.

BACKGROUND: Genetic factors and night shift work both contribute to the risk of depression, but whether the association of night shift work with depression varies by genetic predisposition remains unclear. OBJECTIVES: To assess whether night shift work is associated with a higher risk of depression regardless of genetic predisposition. METHODS: We used data from the UK biobank of 247,828 adults aged 38-71 free of depression at baseline from March 13, 2006, to October 1, 2010. Genetic predisposition to depression was assessed using polygenic risk scores (PRS) weighted sums of genetic variant indicator variables and classified as low (lowest tertile), intermediate (tertile 2), and high (highest tertile). Night shift work exposures were collected using a touchscreen questionnaire and were divided into four categories. RESULTS: After a median follow-up of 12.7 years, 7315 participants developed depression. Compared with day workers, HRs (95 % CIs) of depression were 1.28 (1.19-1.38) for shift work, but never or rarely night shifts, 1.32 (1.20-1.45) for irregular night shifts, and 1.20 (1.07-1.34) for permanent night shifts. Considering lifetime employment and compared with never shift workers, >8 nights/month (HR: 1.40; 95 % CI: 1.19-1.66) and <10 years (HR: 1.30; 95 % CI: 1.09-1.54) of night shift work were associated with a higher risk of depression. In joint effect analyses, compared to participants with low genetic predisposition and day workers, the HRs (95 % CIs) of depression were 1.49 (1.32-1.69) in those with high genetic predisposition and shift work, but never or rarely night shifts, and 1.36 (1.20-1.55) for those with high genetic predisposition and irregular/permanent night shifts. In addition, there was neither multiplicative nor additive interaction between genetic predisposition and night shift work on the risk of depression. CONCLUSIONS: Night shift work was associated with an increased risk of depression regardless of genetic risk.

Trabajo a turnos y enfermedades no transmisibles relacionadas con la nutrición / Shift work and non-communicable diseases associated with nutrition

Objetivos: presentar las evidencias disponibles en cuanto al trabajo a turnos y las enfermedades no transmisibles relacionadas con la nutrición, e identificar qué efectos en la salud produce este tipo de trabajo, así como sintetizar las intervenciones más apropiadas para prevenir o tratar dichas patologías. Método: revisión narrativa. Se realizó una búsqueda en las bases de datos Pubmed, Web of Science y Scopus, con los descriptores MeSH: “Shift Work Schedule”, “Rotating Shift Work”, “Night shift work”, “Nutritional Status” y “Nutritional Disorders”. Se utilizaron filtros cronológicos (2018-2023) e idioma (inglés y español). Resultados: fueron seleccionados 29 artículos. Todos los trabajos coinciden en que existen alteraciones en la salud de los trabajadores que realizan trabajo a turnos, teniendo especial efecto en la dieta que seguían. Los principales efectos son el aumento del riesgo cardiovascular con mayores posibilidades de padecer síndrome metabólico, aumento del riesgo de desarrollar hipertensión arterial; peor control glicémico y del peso. En cuanto a intervenciones dietéticas, no se han encontrado trabajos de investigación que aborden esta cuestión. Se encontró una intervención de ocho semanas de ejercicio físico en un gimnasio presente en el lugar donde se trabaja. Conclusiones: el trabajo a turnos rotatorios se asocia con mayor riesgo cardiovascular, debido en gran parte a que estos trabajadores comen peor (mayor cantidad de energía ingerida, sin pautas fijas, abuso de grasas y azúcares, insuficiencia de fibra, etc.) y no realizan ejercicio de manera regular. Son necesarias intervenciones en el ámbito individual, organizacional y colectivo, así como profundizar en la investigación mediante estudios experimentales sobre la dieta. (AU)

Objectives: to present the evidence available regarding shift work and non-communicable diseases associated with nutrition, and to identify the impact on health caused by this type of work, as well as to summarize the most adequate interventions to prevent or treat said conditions. Method: a narrative review. A search was conducted in the Pubmed, Web of Science and Scopus databases, with the MeSH descriptors: “Shift Work Schedule”, “Rotating Shift Work”, “Night shift work”, “Nutritional Status” and “Nutritional Disorders”. The filters used were chronological (2018-2023) and language (English and Spanish). Results: twenty-nine (29) articles were selected. All of them coincided in the existence of alterations in the health of workers who conducted shift work, with particular impact on the diet they followed. The main effects were an increase in cardiovascular risk with higher likelihood of suffering metabolic syndrome, an increase in the risk of developing hypertension, and worse glycemic and weight control. In terms of diet interventions, no research articles addressing this matter were found. An intervention was found regarding eight weeks of physical exercise at a gym in the workplace. Conclusions: shift work was associated with higher cardiovascular risk, mostly due to the fact that these workers followed a worse diet (higher amount of energy ingested, without fixed patterns, abuse of fat and sugar, fibre deficiency, etc.) and did not exercise regularly. Interventions are required in the individual, organizational and collective settings, as well as to delve in research through experimental studies on diet. (AU)

Night shift work was associated with functional outcomes in acute ischemic stroke patients treated with endovascular thrombectomy.

Objective: This study aimed to explore the impact of late night shift work on the functional outcomes of patients with acute ischemic stroke (AIS) treated with endovascular thrombectomy (EVT). Methods: Consecutive AIS patients who underwent EVT between June 2019 and June 2021 were enrolled and divided into non-night shift work and night shift work groups based on their occupational histories. The primary outcome was the modified Rankin Scale score defined 3-month functional outcome. The secondary outcomes were 3-month mortality, symptomatic intracerebral hemorrhage (sICH), ICH and early recanalization. Results: A total of 285 patients were enrolled, 35 patients (12.3%) were night shift workers, who were younger (P < 0.001) and had a significantly higher prevalence of smoking (P < 0.001), hyperlipidemia (P = 0.002), coronary heart disease (P = 0.031), and atrial fibrillation (P < 0.001). The 3-month favorable outcomes were achieved in 44.8% and 25.7% of patients in the non-night shift work and night shift work groups, respectively (adjusted odds ratio [OR]: 0.24, 95% CI: 0.10-0.57; adjusted P = 0.001). No difference was found in 3-month mortality (adjusted OR: 0.43; 95% CI: 0.14-1.25, adjusted P = 0.121), rates of ICH (adjusted OR: 0.73; 95% CI: 0.33-1.60; adjusted P = 0.430), sICH (adjusted OR: 0.75; 95% CI: 0.34-1.67; adjusted P = 0.487), or early successful recanalization (adjusted OR: 0.42; 95% CI: 0.12-1.56; adjusted P = 0.197). These results were consistent after PSM analysis. Conclusion: Our findings suggest that late night shift work is significantly associated with unfavorable outcomes in patients with AIS after EVT.

Latent class analysis of the sleep quality of night shift nurses and impact of shift-related factors on the occupational stress and anxiety.

AIMS: The objective of this study is to explore the various latent categories within the sleep quality of night shift nurses and to investigate whether shift-related factors predispose nurses to higher levels of occupational stress and anxiety. DESIGN: This is a cross-sectional study. METHODS: From November to December 2020, registered nurses from 18 tertiary hospitals and 16 secondary hospitals in Chongqing were selected through convenience sampling for this study. Latent class analysis was used to investigate the sleep quality of nurses working night shifts. Furthermore, univariate analysis and logistic multivariate analysis were utilized to identify the contributing factors to occupational stress and anxiety. RESULTS: The four latent categories of Pittsburgh Sleep Quality Index for night shift nurses were identified as 'Low Sleep Disorder Group' (56.34%), 'Moderate Sleep Disorder Group' (37.27%), 'High Sleep Disorder Non-Reliant on Sleeping medication Group' (4.89%) and 'High Sleep Disorder Reliant on Sleeping medication Group' (1.50%). The results showed that having a night-shift frequency of 3-4 times per month, night-shift durations of 9-12 h, sleep time delay after night shift (≥2 h), total sleep time after night shift less than 4 h were shift-related factors that increased the levels of occupational stress and anxiety. CONCLUSION: The sleep quality of night shift nurses demonstrates heterogeneity and can be classified into four latent categories. Higher frequency of night shifts, extended work hours and insufficient rest time are all associated with increased levels of occupational stress and anxiety. IMPACT: By identifying the four latent categories of sleep quality among night shift nurses, this study sheds light on the relationship between sleep patterns and levels of occupational stress and anxiety. These findings have important implications for healthcare institutions in the management of nurse well-being and work schedules. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution.

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.

Association between night work and prostate cancer: a systematic review and meta-analysis.

OBJECTIVE: The aim was to conduct a systematic review and meta-analysis to study the association between night work and the development of prostate cancer. METHODS: A systematic literature search was conducted in CINAHL, Embase, MEDLINE, and Web of Science. Studies were included based on a PECOS; the population included men in/above the working age, exposure defined as night work, outcome defined as prostate cancer, and study design restricted to cohort studies. The exclusion of articles, risk-of-bias assessment, and data extraction were performed by two reviewers. A meta-analysis was conducted using a random-effects model, including a sensitivity analysis stratified based on the risk-of-bias assessment. We evaluated publication bias using a funnel plot and Egger´s test, and the level of evidence was assessed using GRADE. RESULTS: A total of 528 articles were identified, and eight cohort studies were included. Three studies had a moderate risk of bias, while five studies had a high risk of bias. The meta-analysis showed a pooled hazard ratio (HR) of 1.0 (95% CI 0.6-1.7). In the sensitivity analysis, moderate vs. high risk-of-bias studies showed a pooled HR of 1.2 (95% CI 0.3-4.1) and 0.9 (95% CI 0.6-1.3), respectively. Based on GRADE, the level of evidence was rated low. CONCLUSION: We found no association between night work and the development of prostate cancer. The evidence was assessed as limited and inconsistent. Future studies encompassing consistent definitions of night work, including objective exposure data, are highly warranted.

Preconception sleep duration, non-daytime work schedules, and incidence of spontaneous abortion: a prospective cohort study.

STUDY QUESTION: To what extent do self-reported sleep duration and non-daytime work schedules in either partner affect the rate of spontaneous abortion (SAB)? SUMMARY ANSWER: Incidence of SAB had little association with female sleep duration and a modest positive association with male short sleep duration, female work at night, and discrepant work schedules among partners. WHAT IS KNOWN ALREADY: Several studies have reported an association between short sleep duration in either partner and reproductive health outcomes, including fecundability. Moreover, certain types of female occupational exposures during pregnancy have been associated with an increased risk of SAB. No studies have evaluated SAB risk in relation to male sleep and work schedules, or joint exposures within a couple. STUDY DESIGN, SIZE, DURATION: This prospective cohort study included 9357 female participants and 2602 of their male partners residing in North America (June 2013 to April 2023). PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants enrolled when they were attempting pregnancy and completed self-administered baseline questionnaires about their average sleep duration and work schedules. Among those who conceived, we ascertained SAB and gestational age at loss via follow-up questionnaires. We used multivariable Cox proportional hazards models with gestational weeks as the time scale to estimate hazard ratios (HRs) and 95% CIs relating SAB with sleep duration and non-daytime work schedules for female and male participants, and the couple. We used inverse probability weighting to account for potential selection bias due to the possibility of differential participation of male partners with respect to the exposures. MAIN RESULTS AND THE ROLE OF CHANCE: Compared to female participants with recommended sleep (7-8.9 h), those reporting short sleep duration (<6 h) did not have a higher rate of SAB (HR 0.88, 95% CI 0.69, 1.13). Short self-reported sleep duration among male participants was modestly associated with a higher rate of SAB (adjusted and weighted HR 1.30, 95% CI 0.96, 1.75). Female night work at night (adjusted HR 1.19, 95% CI 1.02, 1.38) and male non-daytime work (adjusted and weighted HR 1.26, 95% CI 1.00, 1.59) were associated with modestly higher rates of SAB, whereas female rotating shift work was not (adjusted HR 0.91, 0.78, 1.05) compared with daytime workers. Couples in which work schedules were discrepant had an elevated rate of SAB if the male partner worked a non-daytime shift (adjusted and weighted HR 1.46, 95% CI 1.13, 1.88) compared with couples in which both members worked during the day. The corresponding HR if only the female partner worked a non-daytime shift was 1.21 (95% CI 0.92, 1.58). LIMITATIONS, REASONS FOR CAUTION: Data on sleep duration and work schedules were based on self-report, which is vulnerable to misclassification, particularly since participants were asked to report their average sleep duration during the past month. Work exposures were heterogeneous, as many different types of employment may require night and shift work and may have different associations with SAB. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are consistent with previous research indicating that some types of female employment schedules may be associated with SAB incidence. This is the first study to indicate a relationship between SAB and male employment schedules, indicating that discrepant work schedules within a couple might be relevant. STUDY FUNDING/COMPETING INTEREST(S): This work was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development grants R01HD105863 (PIs: L.A.W. and M.L.E.), R01HD086742 (PIs: L.A.W. and E.E.H.), and R21HD072326 (PI: L.A.W.). PRESTO has received in-kind donations from Swiss Precision Diagnostics and Kindara.com for primary data collection. L.A.W. is a consultant for AbbVie, Inc. and the Gates Foundation. M.L.E. is an advisor for and holds stock in Ro, Hannah, Dadi, Underdog, Vseat, & Doveras. The other authors have no competing interests to declare. TRIAL REGISTRATION NUMBER: N/A.

Interindividual variability in coherence between self-reported alertness and performance in shift workers.

OBJECTIVES: Evidence indicates that self-reported measures of alertness do not always reflect performance impairments. The present study aims to explore whether subjective and objective measures of vigilance vary in the same direction in individuals working nights. METHODS: A total of 76 police officers participated to a month-long observational study. They worked either a 2 or 3-shift system during which they self-reported alertness and completed a psychomotor vigilance task several times a day. RESULTS: A reduction in alertness and reaction speed was observed with time awake. At the group level, changes in alertness and reaction speed with time awake were positively correlated during night shifts only. In 63.6% of the officers, changes were coherent between both variables. The other officers reported that their alertness dropped (25.5%) or improved (10.9%) whereas their performance changed in the opposite direction. CONCLUSION: Significant interindividual variability exists in self-appraisal vigilance impairment due to night shift work.

Cohort Studies Versus Case-Control Studies on Night-Shift Work and Cancer Risk: The Importance of Exposure Assessment.

It is a general assumption that the prospective cohort study design is the gold standard approach and is superior to the case-control study design in epidemiology. However, there may be exceptions if the exposure is complex and requires collection of detailed information on many different aspects. Night-shift work, which impairs circadian rhythms, is an example of such a complex occupational exposure and may increase the risks of breast, prostate, and colorectal cancer. So far, for logistical reasons, investigators in cohort studies have assessed shift work rather crudely, lacking information on full occupational history and relevant shift-work metrics, and have presented mostly null findings. On the other hand, most cancer case-control studies have assessed the lifetime occupational histories of participants, including collection of detailed night-shift work metrics (e.g., type, duration, intensity), and tend to show positive associations. In this commentary, we debate why cohort studies with weak exposure assessment and other limitations might not necessarily be the preferred or less biased approach in assessing the carcinogenicity of night-shift work. Furthermore, we propose that risk-of-bias assessment and comparison of associations between studies with low versus high risks of bias be considered in future synthesis of the evidence.

Rotating Night Shift Work, Sleep, and Thyroid Cancer Risk in the Nurses' Health Study 2.

Night shift work has been associated with breast, prostate, and colorectal cancer, but evidence on other types of cancer is limited. We prospectively evaluated the association of rotating night shift work, sleep duration, and sleep difficulty with thyroid cancer risk in the Nurses' Health Study 2 (NHS2). We assessed rotating night shift work duration (years) at baseline and throughout follow-up (1989-2015) and sleep characteristics in 2001. Cox proportional hazard models, adjusted for potential confounders, were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for (a) shift work duration, (b) sleep duration, and (c) difficulty falling or staying asleep. We stratified the analyses of night shift work by sleep duration and sleep difficulty. Over 26 years of follow-up, 588 incident cases were identified among 114,534 women in the NHS2 cohort. We observed no association between night shift work and the risk of thyroid cancer. Difficulty falling or staying asleep was suggestively associated with a higher incidence of thyroid cancer when reported sometimes (HR 1.26, 95% CI 0.95, 1.66) and all or most of the time (HR 1.35, 95% CI 1.00, 1.81). Night shift workers (10+ years) with sleep difficulty all or most of the time (HR 1.47; 0.58-3.73) or with >7 h of sleep duration (HR 2.17; 95% CI, 1.21-3.92) had a higher risk of thyroid cancer. We found modest evidence for an increased risk of thyroid cancer in relation to sleep difficulty, which was more pronounced among night shift workers.

Association between shift work and the risk of hypothyroidism in adult male workers in Korea: a cohort study.

Background: Shift work has been reported to have several harmful effects on the human body. However, a small number of studies have evaluated the association between shift work and adverse effects on the thyroid. In our longitudinal study, we examined the causal association between shift work and the risk of hypothyroidism. Methods: A Kangbuk Samsung Cohort Study was conducted on 112,648 men without thyroid disease at baseline who were followed up at least once between 2012 and 2019. Shift work status and shift schedule types were categorized using standardized questionnaires. Hypothyroidism was defined using the reference ranges of serum thyroid-stimulating hormones and free thyroxine levels. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident hypothyroidism were estimated using Cox proportional hazards regression analyses with the daytime work group as the reference. Results: During the 501,237 person-years of follow-up, there were 6,306 incident cases of hypothyroidism (incidence density, 1.26 per 100 person-years). The multivariable-adjusted HR of incident hypothyroidism for the shift work total group that included all shifts compared with the daytime work group was 1.27 (95% CI: 1.15-1.40). For the fixed evening, fixed night, rotating shift, and other shift workers, the multivariable-adjusted HRs (95% CI) were 1.11 (0.76-1.61), 2.18 (1.20-3.93), 1.39 (1.23-1.56), and 1.00 (0.82-1.22), respectively. In subgroup analyses by age, the association between shift work and hypothyroidism was more pronounced in younger participants (< 40 years; HR: 1.31; 95% CI: 1.16-1.47). Conclusions: Our large-scale cohort study showed an association between shift work and the incidence of hypothyroidism, especially in younger workers with night shifts.

A COVID-19 Outbreak in a Large Meat-Processing Plant in England: Transmission Risk Factors and Controls.

The meat-processing industry had frequent COVID-19 outbreaks reported worldwide. In May 2021, a large meat-processing plant in the UK had an outbreak affecting 4.1% (63/1541) of workers. A rapid on-site investigation was conducted to understand the virus transmission risk factors and control measures. This included observational assessments of work activities, control measures, real-time environmental measurements and surface microbial sampling. The production night-shift attack rate (11.6%, 44/380) was nearly five times higher than the production day-shift (2.4%, 9/380). Shared work transport was provided to 150 staff per dayshift and 104 per nightshift. Production areas were noisy (≥80 dB(A)) and physical distancing was difficult to maintain. Face visors were mandatory, additional face coverings were required for some activities but not always worn. The refrigeration system continuously recirculated chilled air. In some areas, the mean temperature was as low as 4.5 °C and mean relative humidity (RH) was as high as 96%. The adequacy of ventilation in the production areas could not be assessed reliably using CO2, due to the use of CO2 in the packaging process. While there were challenges in the production areas, the observed COVID-19 control measures were generally implemented well in the non-production areas. Sixty surface samples from all areas were tested for SARS-CoV-2 RNA and 11.7% were positive. Multi-layered measures, informed by a workplace specific risk assessment, are required to prevent and control workplace outbreaks of COVID-19 or other similar respiratory infectious diseases.