Work Around the Clock: How Work Hours Induce Social Jetlag and Sleep Deficiency.

A growing body of evidence has placed an increasing emphasis on how sleep affects health. Not only does insufficient sleep make one subjectively feel worse, but is associated with chronic diseases that are considered epidemics in industrialized nations. This is partly caused by the growing need for prolonged work and social schedules, exemplified by shift work, late-night weekends, and early morning work/school start times (social jetlag). Here, we consider fundamental relationships between the circadian clock and biologic processes and discuss how common practices, such as shift work and social jetlag, contribute to sleep disruption, circadian misalignment, and adverse health outcomes.

Sleep Deficiency: Epidemiology and Effects.

Adequate sleep is an important pillar of physical and mental health. Sleep deficiency, resulting from short sleep or suboptimal sleep quality, is highly prevalent in modern society. Occupation, social demands, psychiatric disorders, physical disorders, and sleep disorders are some of the contributing factors to sleep deficiency. Some populations are at increased risk of sleep deficiency based on ethnicity, age, marital status, sex, and hospitalization. Sleep deficiency influences cognition, alertness, mood, behavior, diabetes, cardiovascular health, renal function, immune system, and respiratory physiology. This review summarizes the epidemiology and effects of sleep deficiency.

Lifestyle Effects on an Unusual Presentation of Syncope: A Case Report.

We present a 53-year-old Hispanic male with a history of palpitations and chronic marijuana use coming to the emergency department (ED) with three episodes of sudden loss of consciousness that occurred after starting his job as a night shift worker, which led to severe chronic sleep deprivation. These episodes lacked prodromal (chest pain, shortness of breath, palpitations, diaphoresis) and postictal (drowsiness, nausea, confusion, headache) symptoms. Electrocardiograms (EKGs) performed in the ED revealed sinus bradycardia with a heart rate of 54 beats per minute (bpm), which dropped to 37 bpm during admission. Overnight telemetry exhibited sinus pauses, characterized by a delay in atrial activity for at least three seconds. A repeat EKG showed an incomplete right bundle branch block (RBBB). The patient received a final diagnosis of recurrent syncope and was given an implantable loop recorder (ILR). The ILR revealed several sinus pauses over the span of three months with no syncopal episodes. The patient was educated on dietary and lifestyle modifications to reduce the risk of experiencing syncopal episodes. This case study explores a unique presentation of syncope with a multifactorial etiology and discusses the impact of lifestyle behaviors on syncope exacerbation.

Circadian Rhythm Disruption in Cancer Survivors: From Oncogenesis to Quality of Life.

BACKGROUND: Circadian rhythms are approximately 24-hour cycles in physiological and behavioral processes. They are entrained to the external solar day via blue wavelength light. Disruptions in these intrinsic rhythms can lead to circadian dysfunction, which has several negative implications on human health, including cancer development and progression. AIMS: Here we review the molecular mechanisms of circadian disruption and their impact on tumor development and progression, discuss the interplay between circadian dysfunction and cancer in basic scientific studies and clinical data, and propose the potential clinical implications of these data that may be used to improve patient outcomes and reduce cost of treatment. MATERIALS & METHODS: Using scientific literature databases, relevant studies were analyzed to draw overarching conclusions of the relationship between circadian rhythm dysruption and cancer. CONCLUSIONS: Circadian disruption can be mediated by a number of environmental factors such as exposure to light at night, shift work, jetlag, and social jetlag which drive oncogenesis. Tumor growth and progression, as well as treatment, can lead to long-term alterations in circadian rhythms that negatively affect quality of life in cancer survivors.

Perceptions of Sleep Quality, Fatigue, and Cognition Among Women Shift Workers.

OBJECTIVE: To explore the perceptions of sleep quality, levels of fatigue, and cognitive executive function in women shift workers. DESIGN: Qualitative, descriptive study of a sample of participants who participated in a cross-sectional, mixed-methods study. SETTING: Online focus groups. PARTICIPANTS: Women shift workers (N = 14) recruited from the southeastern United States. METHODS: Four focus groups were conducted using the Zoom online videoconferencing platform. Transcripts were coded inductively, and data were analyzed using a thematic analysis approach. RESULTS: Five major themes were developed from the data: Lots of Sleep Lost, Day Sleep Difficulties, Negative Consequences, Missing Out, and Not in My Own Thoughts. CONCLUSION: Shift work is associated with sleep loss, which has a negative impact on women's emotional, mental, and physical health. Further nursing science investigation into strategies to enable women to improve their sleep quality, sleep quantity, and social/domestic environment is warranted. Education to increase sleep knowledge and decrease accidents and errors that can result from insufficient sleep is vital.

Assessment of sleep quality, fatigue and its association with occupational injuries among shift workers in an electronic industrial environment.

Objectives. This study explores the association between sleep quality, cumulative fatigue and occupational injuries among shift workers in Pakistan's manufacturing industries. Methods. The study surveyed 200 shift workers using a self-administered questionnaire. Sleep quality was assessed with the Pittsburgh sleep quality index (PSQI), and fatigue with the standard shiftwork index (SSI). Statistical analyses included t tests, χ2 tests and logistic regression. Results. Night shift employees had higher odds of occupational injuries (odds ratio [OR] 3.591, 95% confidence interval [CI] [1.079, 11.944], p = 0.037) compared to day shift workers. Cumulative fatigue (OR 3.044, 95% CI [1.145, 8.089], p = 0.026) and PSQI global score (OR 1.249, 95% CI [1.002, 1.556], p = 0.048) also indicated an increased injury risk. Conclusion. Night shift workers experienced poorer sleep quality, higher fatigue and increased injuries than day shift workers. Employers should implement artificial intelligence to detect and manage fatigue, set strategic shift schedules for maximum sleep opportunities and train workers to improve sleep quality.

Sleep Habits and Disturbances in Healthcare Workers: A Cross-Sectional Survey in French Public Hospitals.

Purpose: To describe the sleep habits (bedtime hours, waking hours, sleep duration) and to assess the prevalence of sleep disturbances (acute and chronic insomnia, insufficient sleep, perceived sleep debt) among French healthcare workers. Participants and Methods: Nurses and assistant nurses working in public hospitals from the Loire department at different work schedules (2x12h, 2x8h, fixed daytime, fixed nighttime) were asked about their socioprofessional and demographic information, their sleep habits and disturbances during night shifts, and the acceptability of a 20-min nap opportunity. Results: A total of 297 healthcare workers completed the survey with 76% reporting a sleep debt with a lower prevalence for fixed nighttime workers (62%) and a higher prevalence for 2x12 h (84%) workers. The prevalence of acute insomnia was 76% with a significant difference between fixed nighttime (60%) and 2x12 h (82%); whereas the prevalence of chronic insomnia was 35% without any significant difference between working schedules. Moreover, 18% of healthcare workers reported excessive daytime sleepiness, while 13% admitted to using sleep medication at least once a week. Conclusion: French healthcare workers reported poor sleep quality with a high prevalence of sleep debt, acute and chronic insomnia symptoms without an obvious impact of working schedules.

Fasting as an intervention to alter the impact of simulated night-shift work on glucose metabolism in healthy adults: a cluster randomised controlled trial.

AIMS/HYPOTHESIS: Night-shift work causes circadian misalignment and impairs glucose metabolism. We hypothesise that food intake during night shifts may contribute to this phenomenon. METHODS: This open-label, multi-arm, single-site, parallel-group controlled trial involved a 6 day stay at the University of South Australia's sleep laboratory (Adelaide, SA, Australia). Healthy, non-shift-working adults without obesity (N=55; age 24.5 ± 4.8 years; BMI 24.8 ± 2.8 kg/m2) were assigned to the next available run date and cluster randomised (1:1:1) to fasting-at-night (N=20), snack-at-night (N=17), or meal-at-night (N=18) conditions. One participant withdrew from each group, prior to starting the study. Due to study design, neither participants nor people collecting their measurements could be blinded. Statistical and laboratory staff were concealed to study allocation. Participants were fed at calculated energy balance, with the macronutrient composition of meals being similar across conditions. The primary outcomes were a linear mixed-effects model of glucose, insulin and NEFA AUC in response to a 75 g OGTT that was conducted prior to and after 4 consecutive nights of shift work plus 1 night of recovery sleep. Insulin sensitivity, insulinogenic and disposition indexes were also calculated. RESULTS: Night-shift work impaired insulin sensitivity, as measured by insulin AUC (p=0.035) and the insulin sensitivity index (p=0.016) across all conditions. Insulin secretion, as measured by the insulinogenic index, was increased in the fasting-at-night condition only (p=0.030), resulting in a day×condition interaction in glucose AUC (p<0.001) such that glucose tolerance was impaired in the meal-at night (+2.00 [95% CI 1.45, 2.56], p<0.001) and snack at-night (+0.96 [0.36, 1.56], p=0.022) conditions vs the fasting-at-night (+0.34 [-0.21, 0.89]) condition. A day×condition interaction was also observed in NEFA AUC (p<0.001), being higher in the meal-at-night (+0.07 [0.03, 0.10]. p=0.001) and snack-at-night (0.01 [-0.03, 0.05], p=0.045) conditions vs the fasting-at-night condition (-0.02 [-0.06, 0.01]). No adverse events occurred. CONCLUSIONS/INTERPRETATION: The timing of food intake has a critical effect on glucose metabolism during simulated night-shift work, which was readily amendable to a meal re-timing intervention. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12616001556437 FUNDING: This work was funded by the National Health and Medical Research Council (NHMRC), APP1099077.

Adaptive sleep behaviours and shift work tolerance during the transition to shift work.

OBJECTIVE: To evaluate whether recruit paramedics adapt their sleep behaviour during the first 12-months of shift work and to identify sleep behaviours that are associated with better shift work tolerance (SWT) after 12-months of shift work. METHODS: Recruit paramedics (n = 105; Mage = 25.81 years; 51.38% female) were evaluated before (baseline), and after six- and 12-months of shift work. At each timepoint, participants completed questionnaires evaluating their mental health and sleep. Participants also underwent 14 days of sleep and shift monitoring (sleep/work diaries and actigraphy) at each timepoint to examine sleep behaviours, including sleep opportunity (SO), sleep regularity and number of sleep episodes. RESULTS: Linear mixed models found SO increased (on day shifts and rest days), and sleep regularity decreased between baseline and follow-up timepoints. There were no changes in SO (on day shifts, nightshifts, and rest days) or sleep regularity between six- and 12-months of shift work. Latent profile analysis at 12-months follow-up identified high (n = 52), medium (n = 27), and low (n = 9) SWT levels (measured via depression, anxiety, insomnia, sleep quality and sleep efficiency) in paramedics. Reduced sleep regularity (i.e., more irregular sleep) between six- and 12-months of work and prioritising major sleep (rather than naps) at six-months predicted high SWT. CONCLUSIONS: These findings suggest clear SWT levels exist early in paramedics' careers whereby symptoms of depression, anxiety, and insomnia were the strongest contributors to SWT. New paramedics' sleep behaviours, including sleep regularity and prioritisation of longer sleep between nightshifts, may play an important role in influencing how paramedics tolerate shift work.

Psychosocial risk factors of lower urinary tract symptoms among working women.

OBJECTIVES: Lower urinary tract symptoms (LUTS) are prevalent among women, affecting not only their physical well-being but also their quality of working life. This study aimed to assess the relationship between psychosocial factors at work and LUTS among working women. Additionally, we sought to investigate whether women with psychosocial risk factors at work reported reduced quality of life (QOL) and a higher degree of productivity loss from absenteeism and presenteeism. METHODS: An online survey was conducted to collect the demographic characteristics, occupational risk factors, and LUTS among employed Korean women. Shift work, weekly working hours, occupational stress, and emotional labor were surveyed as psychosocial risk factors at work. The association between psychosocial risk factors and LUTS was assessed using adjusted logistic regression. The relationships between psychosocial risk factors and LUTS-related outcomes, such as were examined using a generalized linear model. RESULTS: Of the 1057 participants, 260 (24.6%) and 294 (27.81%) had overactive bladder and urinary incontinence, respectively. Job stress, emotional labor, and night-shift work are significantly associated with a higher prevalence of LUTS, which reduce workers' QOL and labor productivity through absenteeism and presenteeism due to urination symptoms. CONCLUSIONS: Psychosocial factors at work, particularly job stress, emotional labor, and night-shift work, were significantly associated with a higher prevalence of LUTS, leading to reduced QOL and labor productivity due to urination symptoms.

Effects and implementation of an intervention to improve sleep, fatigue and recovery among healthcare workers with night shifts: A pre- and post-test study.

BACKGROUND: Previous intervention studies among night workers mainly focused on single interventions and found inconclusive evidence for effectiveness. A comprehensive intervention approach that includes individual and environmental components has been argued as important. Gaining insight into contributing factors for the implementation of interventions for night workers and effectiveness is important to distinguish between theory and programme failure. OBJECTIVES: To evaluate the effects and implementation of the PerfectFit@Night intervention to improve sleep, fatigue and recovery of night workers in healthcare, using the RE-AIM framework, which assesses reach, effectiveness, adoption, implementation and maintenance of interventions. DESIGN: A prospective pre-post study design, with two measurements before and three and six months after the intervention. SETTING: Twelve different departments of a university hospital in the Netherlands. PARTICIPANTS: Healthcare workers working night shifts (n = 210). METHODS: PerfectFit@Night consisted of environmental (provision of a powernap bed and healthy food, and workshop healthy rostering) and individual elements (e-learning and sleep coaching) and was implemented for three months in a phased manner. Questionnaires, logbooks and interview data were used. Effects of the intervention on sleep, fatigue and recovery were evaluated with mixed-effects models, and implementation factors of reach, adoption, implementation and maintenance were evaluated. RESULTS: Night shift-related insomnia (-11 %-points, 95 % CI: -19 %, -4 % at three months), need for recovery (ß: -2.45, 95 % CI: -4.86, -0.03 at six months) and fatigue (OR: 0.46, 95 % CI: 0.25, 0.86 at six months) decreased significantly after the intervention. No changes were found for subjective sleep quality and sleep duration. Barriers and facilitators for implementation were identified for each intervention element at individual (e.g., dietary preferences), organisational (e.g., responsibilities at work) and workplace levels (e.g., location of power nap bed), and for the intervention itself (e.g., useful information in e-learning). Although satisfaction was high and continuation was preferred, embedding of the intervention in the daily routine was limited. Facilitators for future implementation include a positive attitude towards the intervention, clear guidelines regarding intervention elements, appointment of night workers as ambassadors, and suitable conditions in terms of work demands and for the intervention elements. CONCLUSIONS: The multi-faceted PerfectFit@Night intervention reduced insomnia, fatigue and need for recovery in night workers in healthcare. The most important facilitators to improve the implementation of PerfectFit@Night exist at the organisational level (e.g., positive attitude within the culture and suitable work demands). Combining effect and implementation evaluation is crucial to identify barriers and facilitators that hamper or enhance intervention effects. TRIAL REGISTRATION: The study was registered in the Netherlands Trial Register on 17 January 2021 (trial number NL9224).

Association and interaction effect of shift work and the risk for obstructive sleep apnea on diabetes mellitus in middle-aged Korean workers.

PURPOSE: To investigate the association of shift work and the risk for obstructive sleep apnea (OSA) with diabetes mellitus (DM), and the interaction effect of shift work and the risk for OSA on DM. METHODS: Data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2019-2021 were used. The participants were 3012 employees aged 40 to 59 years. Shift work was assessed using self-reporting questionnaires. The risk for OSA was assessed by STOP-BANG score. The distribution of demographic factors was calculated using the chi-square test. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated using multivariable logistic regression. An interaction effect between shift work and the risk for OSA on DM was evaluated using relative excess risk owing to interaction (RERI) and attributable proportion (AP) with 95% CIs. The synergic index (SI) was also calculated. RESULTS: Shift work and the risk for OSA were each significantly associated with DM. There was also a significant interaction effect between shift work and the risk for OSA on DM. The RERI was 0.543 (95% CI 0.205-1.361) and the AP was 0.230 (95% CI 0.145-0.342). The SI was 1.662 (95% CI 1.481-1.843). CONCLUSIONS: There was an association and a significant interaction effect of shift work and the risk for OSA on DM. The management of OSA in shift workers should be implemented to prevent DM.

Influence of shift work on sleep quality and circadian patterns of heart rate variability among nurses.

Background: Shift work implementation is essential for providing continuous patient care in hospitals. However, working in shifts on a routine basis may disrupt the circadian pattern and alter the sleep-wakefulness cycle in nurses. Stress due to shift work can influence the adaptability of the cardiovascular system, produce psychophysiological strain and deteriorate work performance in female nurses. Objective: This study investigated the effect of morning and night shift work on sleep quality and circadian patterns governing heart rate variability (HRV) in female nurses working in a tertiary care hospital. Methods: Thirty-eight healthy female nurses were recruited. Frequency and time domain parameters of HRV were recorded as markers of cardiac autonomic function. A student t-test was used to investigate differences in HRV between morning and night shift workers. Mann-Whitney non-parametric test was applied for the difference between Pittsburgh Sleep Quality Index (PSQI) scores in the two groups. Results: Standard deviation of the normal-to-normal interval (SDNN) (msec), total power (ms2) and high-frequency (HF) band power (ms2) were significantly reduced in night shift nurses than in morning shift nurses. The low-frequency (LF)/HF ratio was significantly increased in night shift nurses. The differences in standard deviation of the averages of NN intervals (SDaNN) (msec), root mean square of successive differences between adjacent NN intervals (RMSSD), mean NN, very low-frequency (VLF) band power (ms2) and LF band power (ms2) were not statistically significant. The global PSQI score was significantly higher among night shift workers than in morning shifts. Conclusion: Inadequate sleep can disrupt the body's ability to regulate heart rhythm and increase the risk of cardiovascular diseases and mortality. The research suggests a propensity for autonomic imbalance in night shift workers when compared to their counterparts on morning shifts.

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.

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.

Association Between Shift Work and Clean Room Environment on Self-reported Premenstrual Symptoms and Menstrual Pain in Taiwan.

Background: Limited research has delved into the effects of work characteristics on premenstrual symptoms (PMS) in women, which can influence work performance and overlook potential hazards for women in their work environments. This study aimed to investigate the impact of shift work and working in a clean room on premenstrual symptoms, menstrual status, and menstrual pain among employed females in an electronics manufacturer. Methods: A retrospective cohort study was conducted on menstruating female employees between August and December 2014, aged 18-55, who received regular employee health checks. Questionnaires were designed to collect information on demographics, personal lifestyle, menstrual status, menstrual pain scores, and self-reported premenstrual symptoms. Results: Among 7,193 participants, 18.6% reported moderate to severe menstrual pain affecting their work. Female workers who reported shift work showed an increased prevalence of moderate to severe premenstrual symptoms, including fatigue (RR = 1.20), somatic discomforts (RR = 1.04), diarrhea (RR = 1.04), and tension (RR = 1.05). Additionally, shift work was associated with an elevated risk of experiencing a moderate or significant impact of menstrual pain on work (RR = 1.03), menstrual irregularity (RR = 1.30), and high menstrual pain (RR = 1.23). Working in a clean room was associated with an increased risk of high menstrual pain (RR = 1.13). Subjects working shifts in a clean room had the highest pain scores compared to the other groups. Conclusion: This study underscores the association of work-related factors on PMS in female employees. Our findings contribute to a better understanding of premenstrual symptoms in female workers with different work characteristics, emphasizing the potential hazards of work-related factors on female employees.

Potential Association between Shift Work and Serologic Response to Hepatitis B Vaccination among Manufacturing Workers in Republic of Korea.

(1) Background: Shift work can affect physical health and the immune system by altering the body's circadian rhythms. This study investigated the factors associated with the hepatitis B virus (HBV) vaccination response in manufacturing workers, classified by whether they engaged in shift work or not. (2) Methods: This retrospective observational study was conducted among adults employed at two manufacturing companies. Those with negative initial hepatitis B surface antibody (HBsAb) levels before vaccination and who subsequently received a three-dose series of HBV vaccine were enrolled. Hepatitis B surface antibodies were examined for 3 years after the first dose. The endpoint of this study was the failure of a seroprotective anti-HB response after vaccination (HBsAb < 10 mIU/mL). Binary logistic regression models were used to analyze factors associated with response failures. (3) Results: Of the 1103 eligible subjects, 337 (30.6%) were shift workers. The failure rate was numerically higher in the shift workers (9.2%) than in the non-shift workers (7.9%), without statistical significance (p = 0.405). However, after adjustment with the binary logistic regression models, the shift workers had a statistically significantly higher rate of response failures than the non-shift workers (odds ratio 2.87; 95% confidence interval 1.64-5.05, p < 0.001), as did males, older workers, those with a low initial anti-HB titer, those with a vitamin D deficiency, and current smokers. (4) Conclusions: Our findings suggest a possible association between shift work and the serologic responses to HBV vaccination. Novel strategies for vaccination should be considered for shift workers.

Influence of Night Shift Work on Heart Rate Variability in an Age- and Gender-Matched Study Group.

Regular and long-term shift work is associated with a number of chronic diseases. There is some evidence that shift work also has an influence on the autonomous nervous system. Studies that have examined the effect of shift work on heart rate variability (HRV) have not taken into account age and gender. Therefore, the aim of this study was to investigate the influence of night shift based on 24 h long-term analyses carried out on non-night shift days with a matched control group for age and gender. In total, 172 (128 male, 44 female) healthy shift night workers were compared with subjects from a non-night shift worker group at a ratio of 1:1, forming matched pairs based on the subjects' sex and age. HRV parameters were analyzed based on 24 h ECG recording. An analysis of the HRV parameters showed only a small difference but without statistical significance between the two groups with regard to all of the HRV parameters examined (SDNN, RMSSD, NN50, pNN50, VLF, LF, HF, LF/HF, DFA1, and DFA2). An analysis of the subgroup of subjects who had only worked night shifts for a minimum of 10 or 20 years, with the respective pairs matched by age and gender, did not reveal any significant differences between the HRV parameters of employees working night shifts and those not working night shifts. Taking into account qualitative aspects of HRV analysis, this study was thus able to show that working night shifts for many years may not have as big an influence on HRV as had been assumed so far.

Humoral response to anti SARS-CoV2 vaccination at one and seven months is not different in shift workers and non-shift workers.

Since previous studies, mostly performed in healthy adults, show that sleep restriction around time of vaccination impairs antibody response and shift work affects sleep, aim of the study was to test the hypothesis that the antibody response to vaccination is impaired in shift workers, when compared to non-shift workers. Employees (n = 445; mean age 44 ± 11 years; 35 % men) of the Centro Cardiologico Monzino, IRCCS (Milan, Italy) were vaccinated against SARS-CoV2 in February 2021 with an mRNA-based vaccine. Antibody titers were assayed 1 and 7 months later. Differences between groups were assessed using ANOVA, after log-transformation of variables with right-skewed distribution. We report that the antibody titer was significantly higher in shift workers (33 % of employees) compared to non-shift workers at first assay [median (IQR): 2495 (1700; 4665) vs 2060 (1619; 2970) BAU/mL, p = 0.0123], as well as at the second one, and that this difference was abolished after adjustment for previous development of symptomatic COVID-19. Results were not affected by age or sex at birth. These results show that shift workers were able to mount an unimpaired antibody response to vaccination. Since vaccinations were performed during the pandemic urgency, our retrospective study has several limitations, nevertheless it underlines the need for large prospective, controlled studies on the effects of acute and chronic sleep restriction on response to vaccination in the general population and on the impact of shift work on immune response.

Evaluating the impact of shift work on the risk of cardiometabolic disease: A Mendelian randomization study.

BACKGROUND AND AIMS: Evidence is increasingly suggesting that shift work is a risk factor for cardiometabolic disease. However, the causal relationship between shift work and cardiometabolic disease is not yet fully understood. In this study, we employed two-sample Mendelian randomization (MR) to investigate the causal relationship between shift work and the risk of cardiometabolic outcomes. METHODS AND RESULTS: Genome-wide association study (GWAS) statistics for shift work were obtained from the UK Biobank. Mendelian randomization analyses were conducted to explore the causal effects of shift work on cardiometabolic outcomes, using single-nucleotide polymorphisms (SNPs) as instrumental variables. The results suggested a causal effect between shift work and body mass index, body fat percentage, triglycerides, high-density lipoprotein, type 2 diabetes, hypertension, and cardiorespiratory fitness. After correcting for multiple tests, only body mass index and high-density lipoprotein showed significant associations. No causal effects were found between shift work and overweight, obesity, total cholesterol, low-density lipoprotein, fasting glucose, 2-h glucose, fasting insulin, coronary artery disease, myocardial infarction, heart failure, atrial fibrillation, or ischemic stroke. CONCLUSION: This MR study provides genetic evidence for a suggestive causal link between shift work and certain cardiometabolic outcomes. Our research may have the significance of providing insight into public hygiene to improve the understanding of shift work and cardiometabolic disease risk. Further experimental studies are needed to confirm our findings.