Disruption of central and peripheral circadian clocks and circadian controlled estrogen receptor rhythms in night shift nurses in working environments.

Chronic disruption of circadian rhythms by night shift work is associated with an increased breast cancer risk. However, little is known about the impact of night shift on peripheral circadian genes (CGs) and circadian-controlled genes (CCGs) associated with breast cancer. Hence, we assessed central clock markers (melatonin and cortisol) in plasma, and peripheral CGs (PER1, PER2, PER3, and BMAL1) and CCGs (ESR1 and ESR2) in peripheral blood mononuclear cells (PBMCs). In day shift nurses (n = 12), 24-h rhythms of cortisol and melatonin were aligned with day shift-oriented light/dark schedules. The mRNA expression of PER2, PER3, BMAL1, and ESR2 showed 24-h rhythms with peak values in the morning. In contrast, night shift nurses (n = 10) lost 24-h rhythmicity of cortisol with a suppressed morning surge but retained normal rhythmic patterns of melatonin, leading to misalignment between cortisol and melatonin. Moreover, night shift nurses showed disruption of rhythmic expressions of PER2, PER3, BMAL1, and ESR2 genes, resulting in an impaired inverse correlation between PER2 and BMAL1 compared to day shift nurses. The observed trends of disrupted circadian markers were recapitulated in additional day (n = 20) and night (n = 19) shift nurses by measurement at early night and midnight time points. Taken together, this study demonstrated the misalignment of cortisol and melatonin, associated disruption of PER2 and ESR2 circadian expressions, and internal misalignment in peripheral circadian network in night shift nurses. Morning plasma cortisol and PER2, BMAL1, and ESR2 expressions in PBMCs may therefore be useful biomarkers of circadian disruption in shift workers.

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.

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.

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.

Night Shift Work Associates with All-Cause and Cause-Specific Mortality: A Large Prospective Cohort Study.

BACKGROUND: Health problems associated with shift work and night shift work are gaining increasing public attention. OBJECTIVE: To investigate the association between night shift work and the hazard of mortality. DESIGN: Prospective cohort study. PARTICIPANTS: A total of 283,579 individuals with paid employment or self-employment aged 37-73 years were included from the UK Biobank with a median follow-up period of 14.0 years. MAIN MEASURES: Participants were divided into day workers and shift workers, including the frequency of night shifts, to evaluate the association between baseline work schedules and all-cause and cause-specific mortality using the Cox proportional hazards model. Additionally, 75,760 participants with work histories were assessed for the association between average frequency and cumulative years of exposure to night shift work and all-cause and cause-specific mortality. KEY RESULTS: Compared with that of day workers, the adjusted hazard of all-cause mortality was increased by 12.0% (hazard ratio [HR], 1.12; 95% confidence interval [CI], 1.07-1.18) in shift workers, particularly in those with no or rare night shifts (approximately 16.1%; HR, 1.16; 95% CI, 1.08-1.25) and those with irregular night shifts (approximately 9.2%; HR, 1.09; 95% CI, 1.00-1.19). Moreover, a non-linear relationship was identified between cumulative night shift years and all-cause and cause-specific mortality. Only individuals who worked night shifts for 20-30 years exhibited a substantially increased hazard of all-cause (HR, 1.52; 95% CI, 1.15-2.00) and cardiovascular disease (CVD; HR, 2.08; 95% CI, 1.16-3.71) mortality. CONCLUSIONS: Shift workers, particularly those with rare or irregular night shifts, exhibited an increased hazard of mortality. Additionally, participants who worked night shifts for 20-30 years exhibited a substantially increased hazard of all-cause and CVD mortality.

The Effect of Meal Glycemic Index and Meal Frequency on Glycemic Control and Variability in Female Nurses Working Night Shifts: A Two-Arm Randomized Cross-Over Trial.

BACKGROUND: Night shift workers are exposed to circadian disruption, which contributes to impaired glucose tolerance. Although fasting during the night shift improves glucose homeostasis, adhering to this dietary strategy may be challenging. OBJECTIVES: This study evaluated the effect of fasting compared with the consumption of meals with different combinations of glycemic index (GI, low or high) and frequency (1 or 3 times) during the night shift on continuous glucose monitoring metrics. METHODS: A 2-arm randomized cross-over trial was conducted on female nurses working night shifts. In each of those arms, the participants were either provided with no meal (fasted), low GI, or high-GI meal during the night shift with a meal frequency according to which arm they were randomly allocated to, either 1-MEAL or 3-MEAL. Outcome variables were glycemic control and variability (GC and GV) metrics during the night shift (21:30-7:00), in the morning after the night shift (07:00-13:00), and in the 24 h period (18:00-18:00). RESULTS: Compared to no meal, the consumption of 1 high-GI meal increased all GV metrics not only during the night shifts but also in the morning, for instance, as observed in the coefficient of variation (ß = 0.03 mmol/L; 95% CI: 0.01, 0.05), and GV percentage (ß = 4.13; 95% CI: 2.07, 6.18). The consumption of 1 or 3 low GI meals did not raise GC or GV metrics except for continuous overall net glycemic action during the night shifts after consuming 3 low GI meals. When controlling for GI, night shift meal frequency did not affect any metrics in any timeframe. CONCLUSIONS: High meal GI but not higher meal frequency during the night shift increased GC and GV in female night shift workers. Results for 1 low-GI meal during the night shift were not different from a glucose profile after no meal. This trial was registered at trialsearch.who.int as NL8715.

The effect of meal frequency and glycemic index during the night shift on alertness, hunger and gastrointestinal complaints in female health care workers - a two-armed randomized cross-over trial.

BACKGROUND: Nutrition strategies for night shift workers could optimize alertness, and minimize hunger and reduce gastrointestinal complaints, enhancing safety and well-being. OBJECTIVE: To investigate the effects of 1 or 3 small meals, with either low or high glycemic index (GI), compared to no meal, on alertness, hunger, and gastrointestinal complaints during the night shift. METHODS: Fifty-one female healthcare workers, aged 18 to 61, participated in a 2-armed randomized cross-over design. In one study arm, participants received one yogurt meal during the night shift, in the other, they received three. Each study-arm involved three intervention periods during night shifts, with participants consuming yoghurt with low GI (1LGI or 3LGI), high GI (1HGI or 3HGI) carbohydrates or no meal (0NGI). Objective alertness was assessed using a validated brief psychomotor vigilance task (PVT-B), subjective alertness with the Samn-Perelli scale, and hunger and gastrointestinal complaints through questionnaires. RESULTS: Participants in the 1LGI (ß -4.6; 95% CI 0.0, 9.3) and 3LGI (ß -3.4; 95% CI 0.0, 6.8) conditions had fewer lapses during the PVT-B than those in the 3HGI condition. No differences were found between meal conditions for median and reciprocal reaction time or subjective alertness. All four conditions reported less hunger (ß from -0.6 to -1.2) compared to no meal. The 3LGI condition resulted in more rumbling intestines than the 3HGI (ß 1.1; 95% CI 0.4, 1.7) and 0NGI (ß 0.74; 95% CI 0.11, 1.37) conditions. CONCLUSIONS: Our study suggests that consuming three small low GI meals during the night shift helps maintain alertness, and reduces lapses compared to three high GI meals. It also minimizes hunger but may cause mild gastrointestinal complaints. https://trialsearch.who.int/Trial2.aspx?TrialID=NL-OMON25574.

Dietary taste patterns and diet quality of female nurses around the night shift.

PURPOSE: Night shift workers are at risk of making poor food choices: e.g. sleep deprivation may lead to higher food intake with innate preferred tastes, such as sweet, savoury and fatty foods. Therefore, better insight in dietary taste patterns of night shift workers may improve the understanding of their food choices. METHODS: This observational study assessed dietary taste patterns of 120 female night shift working nurses and compared them to 307 women of a reference population. Dietary intake, assessed with 24-h dietary recalls, was combined with a taste intensity database, including taste profiles of 557 foods. The contribution to the daily intake of 6 taste clusters was assessed: fat, neutral, sweet/fat, sweet/sour, salt/umami/fat and bitter. RESULTS: During night shifts, nurses consumed a significantly higher energy percentage (en%) of 'neutral' (5.9 en%), 'sweet/sour' (8.1 en%) and 'sweet/fat' (6.5 en%) tasting foods and a lower en% of 'fat' (- 17.1 en%) and 'bitter' (- 2.1 en%) tasting foods than outside the night shift. They consumed a larger en% from foods with a 'sweet/sour' (1.9 en%) taste and a lower en% from foods with a 'bitter' (- 2.1 en%) taste than the reference population, irrespective of age, BMI and smoking status. A higher en% and gram% of 'fat' tasting foods and a higher gram% 'fat/salt/umami' tasting foods were associated with lower diet quality. CONCLUSION: Our results only partly support our hypothesis that nurses would select foods with more innate taste preferences. In addition, fat and savoury tasting foods were negatively associated with their diet quality.

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.

Prevalence and characterization of sleep quality and insomnia in security guards working on the day and night shift in Delhi-NCR.

BACKGROUND: In today's modern world, shift working has become an important part of society and industrial work; prolonged wakefulness is a widespread phenomenon due to which the sleep patterns of individuals are getting disturbed, and many sleep disorders are arising. PURPOSE: This study compared the sleep quality and insomnia of the security guards working the day and night shifts. METHODS: This observational study comprised 100 security guards from Delhi and the NCR region. Self-administered questionnaires, i.e., the Pittsburgh sleep quality index (PSQI) and the Athens Insomnia Scale (AIS), were used to assess sleep quality and insomnia. Fifty questionnaires were filled out by the day shift security guards, and the night shift security guards filled out 50. The data underwent analysis, and a comparison was conducted between security workers on night and day shifts using a Mann-Whitney U test, with a significance level set at p < 0.05. RESULTS: The result revealed a significant difference (95% CI; p < 0.05) for the variables, sleep quality and insomnia when compared between night and day shift working security guards. Among night shift workers, 74% reported issues with sleep quality and 48% experienced insomnia. In comparison, among day shift workers, 58% reported concerns about sleep quality, while 32% reported experiencing insomnia. CONCLUSION: The study concluded that night-shift working security guards had poorer sleep quality and a higher prevalence of insomnia compared to their day-shift counterparts. These differences are highly significant, highlighting the potential adverse effects of night shift work on sleep health, urging the need for interventions to improve sleep quality and manage insomnia among night shift workers.

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.

Night shift work and female breast cancer: a two-stage dose-response meta-analysis for the correct risk definition.

INTRODUCTION: The hypothesis of this study is night shift work exposure can increase the risk of female breast cancer. To validate this hypothesis, the authors conducted a two-stage dose-response meta-analysis with improved quality on this topic. METHODS: The medical librarian searched PubMed, EMBASE, and the Cochrane Library on December 30th, 2022. The eight inclusion criteria were determined and strictly applied to the selection process. A reliable dose-response meta-analysis methodology was applied. RESULTS: Reliable 10 cohort (total cases: 15,953, and total person-years: 6,812,138) and 11 case-control reports (total cases: 9196, and total controls:12,210) were included in the final analysis. The pooled risk ratio (RR) of female breast cancer (from cohort studies) for 1, 10, 20, and 30 years of night shift work exposure was 1.0042 (95% CI 1.0014-1.0070), 1.0425 (95% CI 1.0138-1.0719), 1.0867 (95% CI 1.0278-1.1490), and 1.1328 (95% CI 1.0419-1.2317), respectively. The pooled odds ratio (OR) of female breast cancer (from case-control studies) for 1, 10, 20, and 30 years of night shift work exposure was 1.0213 (95% CI 1.0108-1.0319), 1.2346 (95% CI 1.1129-1.3695), 1.5242 (95% CI 1.2386-1.8756), and 1.8817 (95% CI 1.3784-2.5687), respectively. DISCUSSION: This study has several strengths from the perspective of a dose-response meta-analysis: Strictly applied eight inclusion criteria, separately synthesized RRs from cohort studies and ORs from case-control studies, clearly defined exposure dose, years of night shift work for each risk estimate, a reliable dose-response meta-analysis methodology, and careful considering of selection, exposure, and outcome biases and confounder adjustment for each study. This careful consideration of potential biases and confounding led to the exclusion of unreliable two cohort and five case-control studies.

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.

Personalized sleep and nutritional strategies to combat adverse effects of night shift work: a controlled intervention protocol.

BACKGROUND: Working during the night interferes with the timing of normal daily activities and is associated with an increased risk of chronic diseases. Under controlled experimental conditions, interventions focusing on sleep and nutrition can mitigate the short-term adverse effects of shift work. However, it is unclear how these results translate to real-life, how they can be targeted to individual conditions, and how they relate to long-term health. Therefore, the current study aims to implement a personalized sleep and nutritional intervention among night shift workers in the field. METHODS: A non-blinded controlled intervention study is used, consisting of a run-in period, an intervention of 3 months, post-intervention measurements, and a follow-up after 12 months. Three study arms are included: sleep intervention, nutritional intervention, and control group (n = 25 each). Participants are healthy 18-60-year male night shift workers, with at least one year of experience in night shift work. Information from the run-in period will be used to personalize the interventions. The main outcomes are sleep measurements and continuous interstitial glucose levels. Furthermore, general health biomarkers and parameters will be determined to further evaluate effects on long-term health. DISCUSSION: This study aims to mitigate negative health consequences associated with night shift work by introducing two personalized preventive interventions. If proven effective, the personalized interventions may serve as practical solutions that can have a meaningful impact on the sustainable health and employability of night shift workers. This study will thereby contribute to the current need for high-quality data on preventative strategies for night shift work in a real-life context. TRIAL REGISTRATION: This trial has been registered under ClinicalTrials.gov Identifier NCT06147089. Registered 27 November 2023.

Effects of chronotype on sleep, mood and cardiovascular circadian rhythms in rotating night shift medical workers.

PURPOSE: Whether chronotype affects the health outcomes of night shift work populations is unknown. This study aimed to assess the influence of different chronotypes in the rotating night shift population on sleep status, mood, blood pressure (BP), and heart rate variability (HRV), as well as the circadian rhythm of BP and HRV. METHODS: A total of 208 rotating night shift workers were included. All participants completed structured questionnaires to assess chronotype, mood and sleep status. During their daily lives outside of the night shift, they underwent 24-hour Holter electrocardiogram monitoring and 24-hour ambulatory blood pressure monitoring. Day-time and night-time BP and BP dipping were obtained. Day-time and night-time HRV values (SDNN, RMSSD, LF, HF, LF nu, SD1, SD2 and SD2/SD1) were calculated and fitted to the cosine period curve. Three circandian parameters (mesor, amplitude and acrophase) were extracted to quantify the circadian rhythm of the HRV indices. RESULTS: Among all three groups, E-type showed more fatigue and sleepiness. In addition, E-type showed blunted diastolic BP dipping. Notably, E-type showed association with higher RMSSD, LF, HF and SD1 in the night time, and higher mesors of RMSSD and LF and amplitude of SD2/SD1 in circadian analysis. CONCLUSION: Chronotype is a factor affecting fatigue, sleepiness and cardiovascular circadian rhythms of rotating night shift workers. Chronotype should be taken into consideration for managing night-shift rotation to promote occupational health.

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.

Strategies that nurses working irregular night shifts use to improve sleep quality: A qualitative study among good and poor sleepers.

AIMS: To assess the sleep strategies that nurses working irregular night shifts use to improve their sleep quality, and to compare the strategies of good and poor sleepers to determine whether the differences between the two groups could provide insights into possible effective strategies. DESIGN: A qualitative descriptive study. METHODS: The study was conducted from September 2019 to January 2020. Thirty-four nurses working irregular night shifts participated; 17 were classified as good sleepers and 17 as poor sleepers based on the Sleep-Wake Experience List, a validated self-report instrument that measures one's sleep quality. Interviews were conducted using open questions to explore strategies around the night-shift set. The interviews were analysed using thematic analysis. FINDINGS: Both groups described similar and different strategies that help them work and sleep well during and after night shifts. However, good sleepers mentioned a greater number of strategies and seemed to have thought about them more than poor sleepers. The most common strategies were having a clear structure, being organized-especially regarding sleeping time-maintaining a daily routine and adjusting their sleep environment. CONCLUSION: Healthcare institutions should consider offering education and training programs aimed at empowering nurses who work irregular night shifts. These programs should provide nurses with various sleep strategies to enhance their sleep quality and overall well-being. IMPLICATIONS FOR THE PROFESSION: Nurses working irregular night shifts can possibly enhance their sleep quality by making personalized plans, for example, including a clear day structure, or an optimized sleep environment. IMPACT: The study focused on how nurses working night shifts could possibly enhance their sleep quality. The findings highlight the importance of providing nurses with diverse sleep strategies to improve sleep quality, helping them to identify what works best for them and consistently apply these strategies. REPORTING METHOD: The Consolidated Criteria for Reporting Qualitative Research guidelines were followed. PATIENT OR PUBLIC CONTRIBUTION: Nurses working irregular night shifts at Maastricht University Medical Center in Maastricht, the Netherlands, who agreed to participate in the study, engaged in a discussion to assess the relevance of sleep quality to their work. They were also encouraged to share their perspectives during the interviews.

Computational Analyses Reveal Deregulated Clock Genes Associated with Breast Cancer Development in Night Shift Workers.

Breast cancer (BC) is the leading cause of cancer death among women worldwide. Women employed in shift jobs face heightened BC risk due to prolonged exposure to night shift work (NSW), classified as potentially carcinogenic by the International Agency for Research on Cancer (IARC). This risk is linked to disruptions in circadian rhythms governed by clock genes at the cellular level. However, the molecular mechanisms are unclear. This study aimed to assess clock genes as potential BC biomarkers among women exposed to long-term NSW. Clock gene expression was analysed in paired BC and normal breast tissues within Nurses' Health Studies I and II GEO datasets. Validation was performed on additional gene expression datasets from healthy night shift workers and women with varying BC susceptibility, as well as single-cell sequencing datasets. Post-transcriptional regulators of clock genes were identified through miRNA analyses. Significant alterations in clock gene expression in BC compared to normal tissues were found. BHLHE40, CIART, CLOCK, PDPK1, and TIMELESS were over-expressed, while HLF, NFIL3, NPAS3, PER1, PER3, SIM1, and TEF were under-expressed. The downregulation of PER1 and TEF and upregulation of CLOCK correlated with increased BC risk in healthy women. Also, twenty-six miRNAs, including miR-10a, miR-21, miR-107, and miR-34, were identified as potential post-transcriptional regulators influenced by NSW. In conclusion, a panel of clock genes and circadian miRNAs are suggested as BC susceptibility biomarkers among night shift workers, supporting implications for risk stratification and early detection strategies.

The impact of night shift stress and sleep disturbance on nurses quality of life: case in Palestine Red Crescent and Al-Ahli Hospital.

BACKGROUND: Nurses play a vital role in providing round-the-clock care to patients, but the challenges associated with working night shifts can have significant implications for their well-being and quality of life. METHODS: This cross-sectional study aimed to investigate the impact of night shift stress and sleep disturbance on the quality of life among nurses working in Palestine Red Crescent Society and Al-Ahli Hospital. Convenience sampling was used to recruit 189 full-time registered nurses with at least one year of job experience. The participants completed a questionnaire assessing night shift stress, sleep disturbance, and quality of life. Descriptive statistics, correlation analysis, and path analysis were conducted to analyze the data. RESULTS: The results reveal that quality of life has positive and low relationship with both night shift stress and sleep disturbances. Results also reveal that night shift stress had a direct negative impact on the quality of life of nurses. Sleep disturbance was found to mediate the relationship between night shift stress and quality of life, indicating that higher levels of night shift stress were associated with increased sleep disturbance, which, in turn, led to poorer quality of life outcomes. CONCLUSION: These findings highlight the importance of addressing night shift stress and sleep disturbance among nurses to enhance their well-being and improve the quality of care provided to patients. In conclusion, this study contributes to the existing literature by demonstrating the detrimental effects of night shift stress and sleep disturbance on the quality of life of nurses. It emphasizes the importance of implementing interventions and creating supportive work environments that address the unique challenges faced by nurses working night shifts.

Effects of job demands, job resources, personal resources on night-shift alertness of ICU shift nurses: a cross­sectional survey study based on the job demands-resources model.

BACKGROUND: A positive work environment can enhance nursing safety and patient satisfaction while alleviating nurse stress. Conversely, a poor work environment can harm nurses' physical and mental health and compromise the quality of care, particularly in the high-intensity and shift-based setting of the ICU. OBJECTIVES: Based on the Job demands-resources (JD-R) model, this study examined the effects of job demands and job resources in the work environment, as well as personal resources, on the night-shift alertness of ICU shift nurses. METHODS: This cross-sectional correlational exploratory study, conducted from July to September 2022, recruited 291 ICU shift nurses from a hospital in Beijing, China. The Copenhagen Psychosocial Questionnaire (COPSOQ), the Self-resilience scale, the General Self-Efficacy Scale (GSES), and the Psychomotor Vigilance Task (PVT) were used to subjectively and objectively measure the job demands, job resources, personal resources, and night-shift alertness. SPSS 26.0 and Mplus 8.3 were used to analyze the data and construct the structural equation model. RESULTS: The night-shift reaction time was 251.0 ms (Median), indicating a relatively high level of alertness. Job demands were negatively correlated with both job resources (r=-0.570, P < 0.001) and personal resources (r=-0.462, P < 0.001), while a positive correlation existed between job resources and personal resources (r = 0.554, P < 0.001). The results show that increased job demands can lead to higher levels of nurse strain (ß = 0.955, P < 0.001), whereas job resources were found that it can decrease strain (ß=-0.477, P = 0.047). Adequate job resources can enhance motivation directly (ß = 0.874, P < 0.001), subsequently reducing reaction time (ß=-0.148, P = 0.044) and improving night-shift alertness among ICU shift nurses. CONCLUSION: Enhancing ICU shift nurses' work motivation through bolstering job resources can boost night-shift alertness. However, it is noteworthy that, in this study, neither strain nor individual resources significantly influenced nurses' night-shift alertness. This may be attributed to the complexity of the ICU environment and individual differences. Future research should explore the relationship between these factors and nurses' work alertness.