Associations of shift work and night work with risk of all-cause, cardiovascular and cancer mortality: a meta-analysis of cohort studies

The Bitemporal Lens Model-toward a holistic approach to chronic disease prevention with digital biomarkers

Objectives

We introduce the Bitemporal Lens Model, a comprehensive methodology for chronic disease prevention using digital biomarkers.

Materials and Methods

The Bitemporal Lens Model integrates the change-point model, focusing on critical disease-specific parameters, and the recurrent-pattern model, emphasizing lifestyle and behavioral patterns, for early risk identification.

Results

By incorporating both the change-point and recurrent-pattern models, the Bitemporal Lens Model offers a comprehensive approach to preventive healthcare, enabling a more nuanced understanding of individual health trajectories, demonstrated through its application in cardiovascular disease prevention.

Discussion

We explore the benefits of the Bitemporal Lens Model, highlighting its capacity for personalized risk assessment through the integration of two distinct lenses. We also acknowledge challenges associated with handling intricate data across dual temporal dimensions, maintaining data integrity, and addressing ethical concerns pertaining to privacy and data protection.

Conclusion

The Bitemporal Lens Model presents a novel approach to enhancing preventive healthcare effectiveness.

Increased risk of developing cerebro-cardiovascular diseases in police officers: a nationwide retrospective cohort study

BACKGROUND

Police officers face an increased risk of developing cerebro-cardiovascular diseases (CVD). However, current literature lacks population-based cohort studies specifically focusing on this association. This study aimed to investigate the association between police officers and the risk of developing CVD compared with education officers, while accounting for socioeconomic and demographic factors.

METHODS

We used the Korean National Health Insurance Service data spanning from 2009 to 2020. In this population-based retrospective matched cohort study, we identified age, sex, and calendar years of job-enrollment-matched education officers for each police officer. This study evaluated the CVD occurrence, including acute myocardial infarction, ischemic stroke, and hemorrhagic stroke. Using multivariable Cox regression analysis, we determined the risk of developing CVD, expressed as a hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

Among 104,134 police officers and 104,134 education officers, 4,391(42.2%) cases and 3,631(34.9%) cases of CVD occurred, respectively. The mean ± standard deviation age was 38.4 ± 9.4 years in police officers and 38.6 ± 9.5 years in education officers. The proportion of men was 84.8 % in both groups. Police officers were significantly associated with a higher risk of developing CVD compared with education officers, with an adjusted HR of 1.15 (95% CI, 1.09-1.22). In addition, police officers had significantly higher risks for acute myocardial infarction (adjusted HR, 1.16; 95% CI, 1.06-1.26) and ischemic stroke (adjusted HR, 1.17; 95% CI, 1.09-1.25).

CONCLUSIONS

The findings of our study highlight a significant increase in the risk of developing CVD among police officers, particularly among those aged 45 years and older and those with uncontrolled blood pressure compared to their education officer counterparts. Future cohort studies are required to confirm this association.

Cancer-Specific Mortality Odds Ratios in the Food, Accommodation, and Beverage Activities in Italy

OBJECTIVES

This study investigated cancer-specific mortality risks of workers employed in food, accommodation and beverage (FAB) activities. Methods: We performed a case-control study based on countrywide mortality and National Social Insurance data. Adjusted cancer-specific mortality odds ratios (MOR) were calculated. We modeled occupational exposure as "ever/never been employed" in FAB activities, using other sectors as reference. Analysis was performed by gender, length of employment and year of smoke banning. Results: About 20,000 cancer deaths in FAB were analyzed. Working in restaurants was positively associated with cancer of lung (MOR = 1.24), bladder (MOR = 1.24), pharynx, and larynx. Accommodation was associated with cancer of pharynx (MOR = 1.46), while beverage with cancer of liver (MOR = 1.22). Gender, length of employment and smoke banning were found effective in modifying some risks. Conclusions: Workers in FAB sectors were at risk for several cancers.

Ecological momentary assessment of physical activity and sedentary behaviour in shift workers and non-shift workers: Validation study

This study examined the criterion validity of an ecological momentary assessment (EMA)-reported physical activity and sedentary time compared with accelerometry in shift workers and non-shift workers. Australian workers (n = 102) received prompts through a mobile EMA app and wore the Actigraph accelerometer on the right hip for 7-10 days. Participants received five EMA prompts per day at 3-hour intervals on their mobile phones. EMA prompts sent to shift workers (SW-T) were tailored according to their work schedule. Non-shift workers (NSW-S) received prompts at standardised times. To assess criterion validity, the association of EMA-reported activities and the Actigraph accelerometer activity counts and number of steps were used. Participants were 36 ± 11 years and 58% were female. On occasions where participants reported physical activity, acceleration counts per minute (CPM) and steps were significantly higher (β = 1184 CPM, CI 95%: 1034, 1334; β = 20.9 steps, CI 95%: 18.2, 23.6) than each of the other EMA activities. Acceleration counts and steps were lower when sitting was reported than when no sitting was reported by EMA. Our study showed that EMA-reported physical activity and sedentary time was significantly associated with accelerometer-derived data. Therefore, EMA can be considered to assess shift workers' movement-related behaviours with accelerometers to provide rich contextual data.

Sleep quality and the need for recovery among nurses working irregular shifts: A cross-sectional study

BACKGROUND

Shift work affects the mental and physical health of nurses, yet the effect of working irregular shifts on sleep and its association with the need for recovery is under-explored.

OBJECTIVE

The purpose of this study was to investigate the sleep quality of nurses working irregular shifts, including night shifts, and to determine whether sleep quality is associated with the need for recovery.

METHODS

This cross-sectional study included 405 nurses working irregular shifts. Data were collected using an online questionnaire that included sociodemographic characteristics, the Sleep-Wake Experience List, sleep problems, sleep duration, and the Need for Recovery scale. Data analyses included descriptive statistics, chi-square tests, t-tests, logistic and multiple linear regressions.

RESULTS

Nurses who worked irregular shifts had poor sleep quality. Those who also worked night shifts, had significantly poorer sleep quality and experienced more difficulties in daily functioning than those who did not work night shifts. Sleep quality was significantly associated with the need for recovery and this remained so after controlling for confounding variables (β= .554, p = .001).

CONCLUSION

The findings indicate that in nurses who work irregular shifts, the sleep quality is low. In this group, the sleep quality in nurses who work night shifts is lower than in nurses who do not work night shifts. Furthermore, better sleep quality was associated with lower need for recovery. These findings suggest that improving sleep quality in nurses working irregular shifts may lower their need for recovery, which may improve health, and reduce burnout and sickness absence.

Effects of (Poly)phenols on Circadian Clock Gene-Mediated Metabolic Homeostasis in Cultured Mammalian Cells: A Scoping Review

Circadian clocks regulate metabolic homeostasis. Disruption to our circadian clocks, by lifestyle behaviors such as timing of eating and sleeping, has been linked to increased rates of metabolic disorders. There is now considerable evidence that selected dietary (poly)phenols, including flavonoids, phenolic acids and tannins, may modulate metabolic and circadian processes. This review evaluates the effects of (poly)phenols on circadian clock genes and linked metabolic homeostasis in vitro, and potential mechanisms of action, by critically evaluating the literature on mammalian cells. A systematic search was conducted to ensure full coverage of the literature and identified 43 relevant studies addressing the effects of (poly)phenols on cellular circadian processes. Nobiletin and tangeretin, found in citrus, (-)-epigallocatechin-3-gallate from green tea, urolithin A, a gut microbial metabolite from ellagitannins in fruit, curcumin, bavachalcone, cinnamic acid, and resveratrol at low micromolar concentrations all affect circadian molecular processes in multiple types of synchronized cells. Nobiletin emerges as a putative retinoic acid-related orphan receptor (RORα/γ) agonist, leading to induction of the circadian regulator brain and muscle ARNT-like 1 (BMAL1), and increased period circadian regulator 2 (PER2) amplitude and period. These effects are clear despite substantial variations in the protocols employed, and this review suggests a methodological framework to help future study design in this emerging area of research.

Associations between actigraphy-measured sleep duration, continuity, and timing with mortality in the UK Biobank

STUDY OBJECTIVES

To examine the associations between sleep duration, continuity, timing, and mortality using actigraphy among adults.

METHODS

Data were from a cohort of 88 282 adults (40-69 years) in UK Biobank that wore a wrist-worn triaxial accelerometer for 7 days. Actigraphy data were processed to generate estimates of sleep duration and other sleep characteristics including wake after sleep onset (WASO), number of 5-minute awakenings, and midpoint for sleep onset/wake-up and the least active 5 hours (L5). Data were linked to mortality outcomes with follow-up to October 31, 2021. We implemented Cox models (hazard ratio, confidence intervals [HR, 95% CI]) to quantify sleep associations with mortality. Models were adjusted for demographics, lifestyle factors, and medical conditions.

RESULTS

Over an average of 6.8 years 2973 deaths occurred (1700 cancer, 586 CVD deaths). Overall sleep duration was significantly associated with risk for all-cause (p < 0.01), cancer (p < 0.01), and CVD (p = 0.03) mortality. For example, when compared to sleep durations of 7.0 hrs/d, durations of 5 hrs/d were associated with a 29% higher risk for all-cause mortality (HR: 1.29 [1.09, 1.52]). WASO and number of awakenings were not associated with mortality. Individuals with L5 early or late midpoints (<2:30 or ≥ 3:30) had a ~20% higher risk for all-cause mortality, compared to those with intermediate L5 midpoints (3:00-3:29; p ≤ 0.01; e.g. HR ≥ 3:30: 1.19 [1.07, 1.32]).

CONCLUSIONS

Shorter sleep duration and both early and late sleep timing were associated with a higher mortality risk. These findings reinforce the importance of public health efforts to promote healthy sleep patterns in adults.

Mendelian randomization analysis reveals the impact of physical and occupational activities on the risk of gastroesophageal reflux disease and Barrett's esophagus

BACKGROUND

Recent studies have indicated that participating in physical activity may provide a safeguard against gastroesophageal reflux disease (GERD). Nevertheless, the precise links between physical and occupational activity and the occurrence of GERD and Barrett's esophagus (BE) are still uncertain.

METHODS

Conducting univariate and multivariate Mendelian randomization investigations to examine the causal relationship between exposures and outcomes. Genetic variation simulation was used in randomized experiments. Data on physical and occupational activity were obtained from the UK Biobank and GWAS catalog. In the meantime, data on GERD and BE were extracted from a high quality meta-analysis.

RESULTS

The results of univariate Mendelian randomization analysis using multiple methods suggest a causal relationship between strenuous sports or other forms of exercise (as a protective factor) and GERD/BE. At the same time, three types of occupational related physical activities, including heavy manual or physical work, shift work and walking or standing work, are risk factors for GERD/BE and have a causal relationship with them. These results were reconfirmed through multivariate Mendelian randomization analysis, which excluding the influence of other potential confounding factors.

CONCLUSIONS

The findings indicated that strenuous sports or other forms of exercise could lower the likelihood of GERD/BE, while excessive physical strain in the workplace, prolonged periods of standing or walking, and shift work could raise the risk of GERD/BE. Acknowledging this risk and implementing suitable measures can contribute to the prevention of GERD and BE, thus mitigating the associated health burden.

Essential dataset features in a successful obesity registry: a systematic review

BACKGROUND

The prevalence of obesity and the diversity of available treatments makes the development of a national obesity registry desirable. To do this, it is essential to design a minimal dataset to meet the needs of a registry. This review aims to identify the essential elements of a successful obesity registry.

METHODS

We conducted a systematic literature review adhering to the Preferred Reporting Items for Systematic Review and Meta-Analysis recommendations. Google Scholar, Scopus and PubMed databases and Google sites were searched to identify articles containing obesity or overweight registries or datasets of obesity. We included English articles up to January 2023.

RESULTS

A total of 82 articles were identified. Data collection of all registries was carried out via a web-based system. According to the included datasets, the important features were as follows: demographics, anthropometrics, medical history, lifestyle assessment, nutritional assessment, weight history, clinical information, medication history, family medical history, prenatal history, quality-of-life assessment and eating disorders.

CONCLUSIONS

In this study, the essential features in the obesity registry dataset were demographics, anthropometrics, medical history, lifestyle assessment, nutritional assessment, weight history and clinical analysis items.

Effects of working conditions on the perception of night work safety and health effects on nurses

AIM

To examine night working conditions by shift work type and identify the effects of night working conditions on nurses' perceptions of shift work safety and health effects.

BACKGROUND

Night work is the main factor affecting nurses' health. However, the safety of night working conditions has not been sufficiently examined in previous studies.

METHODS

This study used a cross-sectional research design and an online survey using a tool released by the Australian Manufacturing Workers' Union, and the responses of 348 shift work nurses in Korea were analyzed. Logistic regression analysis was used to examine the effects of shift work conditions on the perceived safety of night work and health effects. The STROBE reporting guidelines were utilized, and data were collected from December 1 to December 31, 2021.

RESULTS

The adjusted logistic regression analysis showed that perceived threat to safety and the health effects of shift work were not significant according to shift type. However, night-shift-work nurses who worked alone (P = 0.003), lacked an emergency recovery system (P = 0.026), and had difficulty commuting perceived a threat to their health (P = 0.007). Additionally, nurses who experienced loss of concentration (P = 0.006) and inadequate rest time (P < 0.001) perceived the health effects of shift work.

DISCUSSION

Urgent monitoring of night work conditions is necessary for the 2-shift work type. Nurses must work night shifts together and an emergency system should be established for their safety.

CONCLUSION

Night work conditions should be improved to prevent the hazards of night work and its negative health effects on nurses.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

This study suggests the necessity of a policy to enhance night work safety, including emergency coping systems and sufficient inter-shift rest time.

Occupational physical activity and risk of mortality in women and men: the Tromsø Study 1986-2021

OBJECTIVE

Associations between occupational physical activity (OPA) and mortality risks are inconclusive. We aimed to examine associations between (1) OPA separately and (2) jointly with leisure time physical activity (LTPA), and risk of all-cause, cardiovascular disease (CVD) and cancer mortality, over four decades with updated exposure and covariates every 6-8 years.

METHODS

Adults aged 20-65 years from the Tromsø Study surveys Tromsø3-Tromsø7 (1986-2016) were included. We categorised OPA as low (sedentary), moderate (walking work), high (walking+lifting work) or very high (heavy manual labour) and LTPA as inactive, moderate and vigorous. We used Cox/Fine and Gray regressions to examine associations, adjusted for age, body mass index, smoking, education, diet, alcohol and LTPA (aim 1 only).

RESULTS

Of 29 605 participants with 44 140 total observations, 4131 (14.0%) died, 1057 (25.6%) from CVD and 1660 (40.4%) from cancer, during follow-up (median: 29.1 years, 25th-75th: 16.5.1-35.3). In men, compared with low OPA, high OPA was associated with lower all-cause (HR 0.83, 95% CI 0.74 to 0.92) and CVD (subdistributed HR (SHR) 0.68, 95% CI 0.54 to 0.84) but not cancer mortality (SHR 0.99, 95% CI 0.84 to 1.19), while no association was observed for moderate or very high OPA. In joint analyses using inactive LTPA and low OPA as reference, vigorous LTPA was associated with lower all-cause mortality combined with low (HR 0.75, 95% CI 0.64 to 0.89), high (HR 0.67, 95% CI 0.54 to 0.82) and very high OPA (HR 0.74, 95% CI 0.58 to 0.94), but not with moderate OPA. In women, there were no associations between OPA, or combined OPA and LTPA, with mortality.

CONCLUSION

High OPA, but not moderate and very high OPA, was associated with lower all-cause and CVD mortality risk in men but not in women. Vigorous LTPA was associated with lower mortality risk in men with low, high and very high OPA, but not moderate OPA.

Sneddon's Syndrome and the Capability to Work: With Regard to a Clinical Case

Sneddon's syndrome is a rare condition characterized by the presence of neurocutaneous lesions, including reticular livedo and an increase in thrombotic risk, and it is associated with a greater risk of cerebrovascular disease. It is diagnosed through a skin biopsy and neurological manifestations. In this study, we present a clinical report of a 39-year-old nurse exposed to shift and night work in an intensive care unit. She was diagnosed with Sneddon's syndrome, whose workplace had to be readapted, considering the complications and restrictions of her condition and aiming her protection and healthcare promotion. Night work can exacerbate cerebral and cardiovascular events due to its impact on metabolism, blood pressure profile, and hormone concentrations. Therefore, given a syndrome characterized by an increased thrombotic risk associated with cerebrovascular events, the restriction of night work is imperative. The occupational physician is responsible for intervening in the workplace and preventing long-term consequences for employees.

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 (β = 0.03 mmol/L; 95% CI: 0.01, 0.05), and GV percentage (β = 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.

Causal effect of shifting from precarious to standard employment on all-cause mortality in Sweden: an emulation of a target trial

BACKGROUND

We aimed at estimating the causal effect of switching from precarious to standard employment on the 6-year and 12-year risk of all-cause mortality among workers aged 20-55 years in Sweden.

METHODS

We emulated a series of 12 target trials starting every year between 2005 and 2016 using Swedish register data (n=251 273). We classified precariously employed individuals using a multidimensional approach at baseline as (1) remaining in precarious employment (PE) (73.8%) and (2) shifting to standard employment (26.2%). All-cause mortality was measured from 2006 to 2017. We pooled data for all 12 emulated trials and used covariate-adjusted pooled logistic regression to estimate intention-to-treat and per-protocol effects via risk ratios (RRs) and standardised risk curves (the parametric g-formula).

RESULTS

Shifting from precarious to standard employment decreases the 12-year risk of death by 20% on the relative scale (RR: 0.82, 95% CI: 0.73; 0.93), regardless of what happens after the initial shift. However, we estimated a 12-year risk reduction of 30% on the relative scale for workers shifting from precarious to standard employment and staying within this employment category for the full 12 years (RR: 0.71, 95% CI: 0.54; 0.95).

CONCLUSIONS

This study finds that shifting from low to higher-quality employment conditions (ie, stable employment, sufficient income levels and high coverage by collective agreements) decreases the risk of death. Remaining in PE increases the risk of premature mortality. Our results emphasise the necessity of ensuring decent work for the entire working population to accomplish the 2030 Agenda for Sustainable Development.

Sleep physiology, pathophysiology, and sleep hygiene

Despite sleep's fundamental role in maintaining and improving physical and mental health, many people get less than the recommended amount of sleep or suffer from sleeping disorders. This review highlights sleep's instrumental biological functions, various sleep problems, and sleep hygiene and lifestyle interventions that can help improve sleep quality. Quality sleep allows for improved cardiovascular health, mental health, cognition, memory consolidation, immunity, reproductive health, and hormone regulation. Sleep disorders, such as insomnia, sleep apnea, and circadian-rhythm-disorders, or disrupted sleep from lifestyle choices, environmental conditions, or other medical issues can lead to significant morbidity and can contribute to or exacerbate medical and psychiatric conditions. The best treatment for long-term sleep improvement is proper sleep hygiene through behavior and sleep habit modification. Recommendations to improve sleep include achieving 7 to 9 h of sleep, maintaining a consistent sleep/wake schedule, a regular bedtime routine, engaging in regular exercise, and adopting a contemplative practice. In addition, avoiding many substances late in the day can help improve sleep. Caffeine, alcohol, heavy meals, and light exposure later in the day are associated with fragmented poor-quality sleep. These sleep hygiene practices can promote better quality and duration of sleep, with corresponding health benefits.

The Feasibility of a Text-Messaging Intervention Promoting Physical Activity in Shift Workers: A Process Evaluation

Workplace health promotion programs (WHPPs) can improve shift workers' physical activity. The purpose of this paper is to present the process evaluation of a text messaging health promotion intervention for mining shift workers during a 24-day shift cycle. Data collected from intervention participants with a logbook (n = 25) throughout the intervention, exit interviews (n = 7) and online surveys (n = 17) examined the WHPP using the RE-AIM (Reach, Efficacy, Adoption, Implementation and Maintenance) framework. The program reached 66% of workers across three departments, with 15% of participants dropping out. The program showed the potential to be adopted if the recruitment strategies are improved to reach more employees, especially when involving work managers for recruitment. A few changes were made to the program, and participant adherence was high. Facilitators to adopt and implement the health promotion program included the use of text messaging to improve physical activity, feedback on behaviour, and providing incentives. Work-related fatigue was reported as a barrier to implementing the program. Participants reported that they would recommend the program to other workers and use the Mi fitness band to continue monitoring and improving their health behaviour. This study showed that shift workers were optimistic about health promotion. Allowing for long-term evaluation and involving the company management to determine scale-up should be considered for future programs.

Alterations in Pregnenolone and Testosterone Levels in Male Shift Workers

Steroid hormone levels are closely related to the endogenous circadian rhythm induced by sleep-wake and dark-light cycles. Shift work that disrupts the circadian rhythm may influence the levels of steroid hormones. The association between shift work and alterations in female sex steroid hormone levels has been studied, but little is known about testosterone and its precursor pregnenolone levels in male shift workers. The present study investigated serum pregnenolone and testosterone levels in a group of shift and daytime male workers. All participants were sampled at the beginning of the morning shift. Lower levels of serum pregnenolone and total testosterone were found in the shift workers compared to the daytime workers. Variations in pregnenolone levels may have consequences for well-being, and they might produce consequences for the levels of hormones downstream of the steroid hormone cascade, such as testosterone. The low levels of testosterone found in shift workers demonstrate the perturbative effect of shift work on testosterone serum levels, which may be independent and/or related to pregnenolone synthesis.

The role of insufficient sleep and circadian misalignment in obesity

Traditional risk factors for obesity and the metabolic syndrome, such as excess energy intake and lack of physical activity, cannot fully explain the high prevalence of these conditions. Insufficient sleep and circadian misalignment predispose individuals to poor metabolic health and promote weight gain and have received increased research attention in the past 10 years. Insufficient sleep is defined as sleeping less than recommended for health benefits, whereas circadian misalignment is defined as wakefulness and food intake occurring when the internal circadian system is promoting sleep. This Review discusses the impact of insufficient sleep and circadian misalignment in humans on appetite hormones (focusing on ghrelin, leptin and peptide-YY), energy expenditure, food intake and choice, and risk of obesity. Some potential strategies to reduce the adverse effects of sleep disruption on metabolic health are provided and future research priorities are highlighted. Millions of individuals worldwide do not obtain sufficient sleep for healthy metabolic functions. Furthermore, modern working patterns, lifestyles and technologies are often not conducive to adequate sleep at times when the internal physiological clock is promoting it (for example, late-night screen time, shift work and nocturnal social activities). Efforts are needed to highlight the importance of optimal sleep and circadian health in the maintenance of metabolic health and body weight regulation.

PPARγ Acetylation Orchestrates Adipose Plasticity and Metabolic Rhythms

Systemic glucose metabolism and insulin activity oscillate in response to diurnal rhythms and nutrient availability with the necessary involvement of adipose tissue to maintain metabolic homeostasis. However, the adipose-intrinsic regulatory mechanism remains elusive. Here, the dynamics of PPARγ acetylation in adipose tissue are shown to orchestrate metabolic oscillation in daily rhythms. Acetylation of PPARγ displays a diurnal rhythm in young healthy mice, with the peak at zeitgeber time 0 (ZT0) and the trough at ZT18. This rhythmic pattern is deranged in pathological conditions such as obesity, aging, and circadian disruption. The adipocyte-specific acetylation-mimetic mutation of PPARγ K293Q (aKQ) restrains adipose plasticity during calorie restriction and diet-induced obesity, associated with proteolysis of a core circadian component BMAL1. Consistently, the rhythmicity in glucose tolerance and insulin sensitivity is altered in aKQ and the complementary PPARγ deacetylation-mimetic K268R/K293R (2KR) mouse models. Furthermore, the PPARγ acetylation-sensitive downstream target adipsin is revealed as a novel diurnal factor that destabilizes BMAL1 and mediates metabolic rhythms. These findings collectively signify that PPARγ acetylation is a hinge connecting adipose plasticity and metabolic rhythms, the two determinants of metabolic health.

Shift Work and Obesity Risk-Are There Sex Differences?

PURPOSE OF REVIEW

Shift work is prevalent among the working population and is linked to an array of adverse health outcomes. This review summarizes current evidence on the relation between shift work and risk of obesity, with a particular emphasis on potential sex differences.

RECENT FINDINGS

Observational data strongly point towards an association between shift work and heightened risk of prevalent and incident obesity, and particularly abdominal obesity. Circadian misalignment and unhealthy lifestyle behaviors are the primary culprits mediating such association. As it pertains to sex differences in the impact of shift work on obesity, few studies have examined this aspect, and findings are conflicting. Shift work is an important risk factor for obesity, with likely multiple biological and behavioral mediators. However, whether there is a sex-dependent vulnerability to the obesogenic effects of shift work is unclear. This area presents opportunities for future research.

Changes in the Work Schedule of Nurses Related to the COVID-19 Pandemic and Its Relationship with Sleep and Turnover Intention

Background: This study aimed to investigate whether different types of changes in the work schedule of nurses working rotating shifts during the COVID-19 pandemic were associated with sleep duration, sleep quality, and turnover intention. Methods: Cross-sectional questionnaire data from 694 nurses participating in the SUrvey of Shift work, Sleep and Health (SUSSH) were collected between the first and the second wave of the COVID-19 pandemic in Norway. A total of 89.9% were female, and mean age was 44.6 years (SD = 8.6 years). Changes in the shift work schedule related to the pandemic comprised reports of more long workdays (>8 h), less days off between work periods, more night shifts, more quick returns (i.e., 11 h or less between two consecutive shifts), more day shifts, and more evening shifts compared to no change in the respective shift characteristics. Change in sleep duration, sleep quality, and turnover intention as well as demographics were also assessed. Logistic regression analyses were performed to investigate whether changes in the specific work schedules were associated with sleep duration, sleep quality, and turnover intention, controlling for sex, age, cohabitation, children living in household, percentage of full time equivalent and other changes in the work schedule. Results: A total of 17% reported experiencing one or more changes in their work schedule during the pandemic. Experiencing any change in the work schedule predicted worse sleep quality (OR = 2.68, p < 0.001), reduced sleep duration (OR = 4.56, p < 0.001), and higher turnover intention (OR = 1.96, p = 0.006) compared to experiencing no change in work schedule. Among the specific changes in work schedules, experiencing an increase in quick returns had the highest odds ratio for worse sleep quality (OR = 10.34, p = 0.007) and higher turnover intention (OR = 8.49, p = 0.014) compared to those who reported no change in quick returns. Nurses experiencing an increase in long workdays were more likely to report higher turnover intention (OR = 4.37, p = 0.003) compared to those experiencing no change in long workdays. Conclusions: Change in work schedule related to the pandemic was associated with worse sleep quality, reduced sleep duration, and higher turnover intention. Increase in quick returns emerged as especially problematic in terms of sleep quality and turnover intention, along with long workdays, which were associated with higher turnover intention.

Associations between circadian misalignment and telomere length in BD: an actigraphy study

BACKGROUND

Life expectancy is significantly decreased in bipolar disorder (BD). This is associated with accelerated cellular aging which can be estimated by telomere length (TL). However, specific determinants of shorter TL in BD are under-explored. This study examines whether circadian misalignment (i.e. mismatch between preferred and actual phase of circadian activity rhythms) is associated with shorter TL in BD.

METHODS

Euthymic individuals with BD (n = 101) undertook 21 consecutive days of actigraphy recording and completed the Composite Scale of Morningness (CSM) to assess phase preference for activities (chronotype). Polymerase chain reaction was used to measure TL in blood. Cluster analysis identified circadian aligned/misaligned subgroups as defined by preferred (CSM score) and actual phases of activity (actigraphically determined onset of active and inactive periods). We tested for any associations between TL and clusters, with adjustments for between-cluster differences in socio-demographic and illness factors.

RESULTS

We identified three clusters: an "Aligned Morning" cluster (n = 31) with preferred and actual timing of activity in the morning, an "Aligned Evening" cluster (n = 37) with preferred and actual timing of activity in the evening and a "Misaligned" cluster (n = 32) with an evening chronotype, but an earlier objective onset of active periods. After adjustment for confounders, we found that TL was significantly associated with circadian misalignment and older age.

CONCLUSIONS

Circadian misalignment may partly explain shorter TL in BD and could contribute to accelerated aging in these individuals.

Sleep problems and risk of cancer incidence and mortality in an older cohort: The Cardiovascular Health Study (CHS)

BACKGROUND

Sleep problems (SP) can indicate underlying sleep disorders, such as obstructive sleep apnea, which may adversely impact cancer risk and mortality.

METHODS

We assessed the association of baseline and longitudinal sleep apnea and insomnia symptoms with incident cancer (N = 3930) and cancer mortality (N = 4580) in the Cardiovascular Health Study. We used Cox proportional hazards regression to calculate adjusted hazard ratios (HR) and 95% confidence intervals (CI) to evaluate the associations.

RESULTS

Overall, 885 incident cancers and 804 cancer deaths were identified over a median follow-up of 12 and 14 years, respectively. Compared to participants who reported no sleep apnea symptoms, the risk of incident cancer was inversely associated [(HR (95%CI)] with snoring [0.84 (0.71, 0.99)]. We noted an elevated prostate cancer incidence for apnea [2.34 (1.32, 4.15)] and snoring [1.69 (1.11, 2.57)]. We also noted an elevated HR for lymphatic or hematopoietic cancers [daytime sleepiness: 1.81 (1.06, 3.08)]. We found an inverse relationship for cancer mortality with respect to snoring [0.73 (0.62, 0.8)] and apnea [(0.69 (0.51, 0.94))]. We noted a significant inverse relationship between difficulty falling asleep and colorectal cancer death [0.32 (0.15, 0.69)] and snoring with lung cancer death [0.56 (0.35, 0.89)].

CONCLUSIONS

The relationship between SP and cancer risk and mortality was heterogeneous. Larger prospective studies addressing more cancer sites, molecular type-specific associations, and better longitudinal SP assessments are needed for improved delineation of SP-cancer risk dyad.