Meta-analysis on shift work and risks of specific obesity types

Meal timing and its role in obesity and associated diseases

Meal timing emerges as a crucial factor influencing metabolic health that can be explained by the tight interaction between the endogenous circadian clock and metabolic homeostasis. Mistimed food intake, such as delayed or nighttime consumption, leads to desynchronization of the internal circadian clock and is associated with an increased risk for obesity and associated metabolic disturbances such as type 2 diabetes and cardiovascular diseases. Conversely, meal timing aligned with cellular rhythms can optimize the performance of tissues and organs. In this review, we provide an overview of the metabolic effects of meal timing and discuss the underlying mechanisms. Additionally, we explore factors influencing meal timing, including internal determinants such as chronotype and genetics, as well as external influences like social factors, cultural aspects, and work schedules. This review could contribute to defining meal-timing-based recommendations for public health initiatives and developing guidelines for effective lifestyle modifications targeting the prevention and treatment of obesity and associated metabolic diseases. Furthermore, it sheds light on crucial factors that must be considered in the design of future food timing intervention trials.

Association between sleep quality and blood pressure control among hypertensive patients at a rural tertiary hospital in Southern Nigeria: a cross-sectional study

OBJECTIVES

Restorative sleep is critical in preventing hypertension and other chronic diseases. Limited research has explored the relationship between sleep quality and hypertension in Africa. This study investigated the association between sleep quality and blood pressure control among hypertensive patients in Southern Nigeria.

DESIGN

Cross-sectional study.

SETTING

A rural tertiary hospital in Southern Nigeria, April to June 2023.

PARTICIPANTS

250 systematically selected hypertensive adults. Participants completed a validated semistructured interviewer-administered questionnaire to assess their sleep patterns, including sleep duration, self-reported trouble sleeping and a history of clinical diagnosis of sleep disorders. Sleep patterns were categorised as restorative (healthy) or non-restorative (unhealthy). The blood pressure of respondents was checked and categorised as controlled (<140/90 mm Hg) or uncontrolled (≥140/90 mm Hg). Data were analysed descriptively using SPSS V.24.0 OUTCOME MEASURES: Quality of sleep and blood pressure control.

RESULTS

Respondents had a mean age of 51.5±10.0 years, with the majority being female (156, 62.4%), married (135, 54.0%) and belonging to the Esan tribe (125, 50.0%). The prevalence of restorative sleep was 36%, while the blood pressure control rate was 23.6%. An association was found between restorative sleep and blood pressure control (adjusted OR =4.38; 95% CI=2.37-8.10; p<0.0001). Respondents aged ≥60 years had 3.5 times higher odds of experiencing non-restorative sleep than those aged ≤40 years (aOR=3.46; 95% CI=1.37-8.74; p=0.009).

CONCLUSION

The study found an association between poor quality sleep and poor blood pressure control. Incorporating sleep assessments and interventions into comprehensive hypertension management strategies could be explored as a possible approach to improve sleep quality and enhance blood pressure control.

TRIAL REGISTRATION NUMBER

PACTR202301917477205.

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.

Rotating shift work time is directly associated with excess body adiposity

OBJECTIVE

To analyze the association between changes in body adiposity and length of service on a schedule of rotating shifts.

METHODS

The study was a cross-sectional investigation conducted during the years 2012, 2015, and 2018, involving individuals engaged in rotating shifts at a company involved in iron ore extraction situated within the Iron Quadrangle region of Minas Gerais and the southeastern region of Pará, Brazil. Sociodemographic and behavioral data were collected along with anthropometric parameters in order to calculate body mass index (BMI) and the waist-to-height ratio (WHtR). For data analysis, a multivariate logistic regression was employed to explore potential associations between indicators of body adiposity and the duration of shift work, employing a hierarchical determination model.

RESULTS

The findings showed that in the multivariate model, controlling for confounding factors, workers with 5 to 10, 10 to 15, and more than 15 years of shift work had 41 to 96% greater odds of being overweight (BMI > 25.0 kg/m2), 71 to 82% of having altered neck circumference (> 40 cm), 33 to 120% of altered WC (>102 cm), and 57 to 214% of having altered WHtR (> 0.5 cm).

CONCLUSION

The findings suggest that time spent in work has a significant effect on anthropometric indicators of body adiposity, especially if the worker has a previously established comorbidity such as dyslipidemia or hypertension and is frequently exposed to night work.

Conceptualizing weight management for night shift workers: A mixed-methods systematic review

Shift workers have an increased risk of obesity and metabolic conditions. This mixed-methods systematic literature review on night shift workers aimed to: (1) identify barriers/enablers of weight management; (2) examine effectiveness of weight management interventions; and (3) determine whether interventions addressed enablers/barriers. Six databases were searched, articles screened by title/abstract, followed by full-text review, and quality assessment. Eligible qualitative studies documented experiences of behaviors related to weight change. Eligible quantitative studies were behavior change interventions with weight/body mass index outcomes. A thematic synthesis was undertaken for qualitative studies using the social-ecological model (SEM). Interventions were synthesized narratively including: weight/body composition change; components mapped by behavior change taxonomy; and SEM. A synthesis was undertaken to identify if interventions addressed perceived enablers/barriers. Eight qualitative (n = 169 participants) and 12 quantitative studies (n = 1142 participants) were included. Barriers predominated discussions: intrapersonal (time, fatigue, stress); interpersonal (work routines/cultural norms); organizational (fatigue, lack of: routine, healthy food options, breaks/predictable work); community (lack of healthy food options). The primary outcome for interventions was not weight loss and most did not address many identified enablers/barriers. One intervention reported a clinically significant weight loss result. Weight loss interventions that address barriers/enablers at multiple SEM levels are needed.

Circadian Adaptation of Melatonin and Cortisol in Police Officers Working Rotating Shifts

Misalignment of behavior and circadian rhythms due to night work can impair sleep and waking function. While both simulated and field-based studies suggest that circadian adaptation to a nocturnal schedule is slow, the rates of adaptation in real-world shift-work conditions are still largely unknown. The aim of this study was to evaluate the extent of adaptation of 24-h rhythms with 6-sulfatoxymelatonin (aMT6s) and cortisol in police officers working rotating shifts, with a special attention to night shifts. A total of 76 police officers (20 women; aged 32 ± 5.4 years, mean ± SD) from the province of Quebec, Canada, participated in a field study during their 28- or 35-day work cycle. Urine samples were collected for ~32 h before a series of day, evening, and night shifts to assess circadian phase. Before day, evening, and night shifts, 60%-89% of officers were adapted to a day schedule based on aMT6 rhythms, and 71%-78% were adapted based on cortisol rhythms. To further quantify the rate of circadian adaptation to night shifts, initial and final phases were determined in a subset of 37 officers with suitable rhythms for both hormones before and after 3-8 consecutive shifts (median = 7). Data were analyzed with circular and linear mixed-effects models. After night shifts, 30% and 24% of officers were adapted to a night-oriented schedule for aMT6s and cortisol, respectively. Significantly larger phase-delay shifts (aMT6s: -7.3 ± 0.9 h; cortisol: -6.3 ± 0.8 h) were observed in police officers who adapted to night shifts than in non-adapted officers (aMT6s: 0.8 ± 0.9 h; cortisol: 0.2 ± 1.1 h). Consistent with prior research, our results from both urinary aMT6s and cortisol midpoints indicate that a large proportion of police officers remained in a state of circadian misalignment following a series of night shifts in dim-light working environments.

The effect of shift work on body mass index: A systematic review and meta-analysis of observational studies

CONTEXT

Shift work involves working outside the standard working hours of 9 am to 5 pm Monday to Friday and may include working evening, night, weekend, or rotating shift patterns. Since shift workers sleep less and their circadian rhythms are disrupted, they are reported to have higher body weight than day workers.

OBJECTIVE

This meta-analysis aims to determine whether shift workers (SW) are more prone to higher body mass index (BMI) than their day workers (DW) counterparts. It also addresses the question of whether the duration of shift work exposure, sex, or occupational type affect BMI value.

METHODS

Four databases that is PubMed, EBSCO Host, Scopus, and Web of Science were searched for reports published up to October 2023.

RESULTS

Sixty-three studies involving a total of 693 449 participants met our inclusion criteria. Meta-analyses showed a significant effect of shift work on BMI value (standard mean difference; SMD: 0.10 kg/m2 [95% confidence interval; 95% CI: 0.07; 0.13; p < .001]) as compared with non-shift counterparts. Subgroup analysis revealed that shift work significantly increased BMI for studies where male working on this job schedule (SMD: 0.10 kg/m2 [95% CI: 0.04; 0.17; p = .0018]) for studies where shift workers worked ≥13 years (calculated as the median of shift work experience; SMD: 0.14 kg/m2 [95% CI: 0.10; 0.18; p < .001]) as well as for studies where industrial (SMD: 0.12 kg/m2 [95% CI: 0.05; 0.19; p = .0012]) and other type of occupations were dominated (0.12 kg/m2 [95% CI: 0.07; 0.16; p < .001]).

CONCLUSIONS

We found that in general working on a shift schedule increases BMI as compared with day workers, especially in case of male employed in this job schedule, for shift workers working for long periods of time (≥13 years), and for shift workers employed in industry and other type of occupations(e.g., airline workers, firefighters, police officers, blue collar, security personnel, bus drivers, garbage collectors, railway workers, postal, oil and gas workers).

Environmental factors of obesity before and after COVID-19 pandemic: a review

In past decades the prevalence of overweight and obesity had grown rapidly. There are numerous factors contributing to this unfavorable change in people's health. This review article investigates the environmental factors which may play a role in the prevalence of overweight and obesity and additionally the novel factors which appeared after the beginning of the COVID-19 pandemic, which caused the increase in BMI during the lockdown period. Most of the studies reveal that the COVID-19 pandemic and lockdown contributed to the growth of BMI in numerous countries and, eventually the prevalence of overweight and obesity increased. Studies suggest that the physical activity was decreased while sleep time and screen time were increased and the amount of food consumed increased, additionally more processed food with long shelf life was consumed. The diverse environmental factors may have an impact on obesity and overweight development taking into account policy and local school policy issues, socioeconomic status, lifestyle including physical activity, diet habits, and amongst others, more trivial causes such as uninteresting neighborhoods, lack of sense of security outside the place of residence or a long distance from shops. Still, this is the object of debate if air pollution is an environmental risk factor influencing the unfavorable trends towards increasing body weight.

The global prevalence of overweight and obesity among nurses: A systematic review and meta-analyses

BACKGROUND

Several studies have reported the prevalence of overweight and obesity in various countries but the global prevalence of nurses with overweight and obesity remains unclear. A consolidation of figures globally can help stakeholders worldwide improve workforce development and healthcare service delivery.

OBJECTIVE

To investigate the global prevalence of overweight and obesity among nurses.

DESIGN

Systematic review with meta-analysis.

SETTING

29 different countries across the WHO-classified geographical region.

PARTICIPANTS

Nurses.

METHODS

Eight electronic databases were searched for articles published from inception to January 2023. Two independent reviewers performed the article screening, methodological appraisal and data extraction. Methodological appraisal was conducted using Newcastle-Ottawa Scale (NOS). Inter-rater agreement was measured using Cohen's Kappa. Meta-analyses were conducted to pool the effect sizes on overweight, obesity and waist circumference using random effects model and adjusted using generalised linear mixed models and Hartung-Knapp method. Logit transformation was employed to stabilise the prevalence variance. Subgroup analyses were performed based on methodological quality and geographical regions. Heterogeneity was assessed using the I2 statistic.

RESULTS

Among 10,587 studies, 83 studies representing 158,775 nurses across 29 countries were included. Based on BMI, the global prevalence of overweight and obesity were 31.2% (n = 55, 95% CI: 29%-33.5%; p < .01) and 16.3% (n = 76, 95% CI: 13.7%-19.3%, p < .01), respectively. Subgroup analyses indicated that the highest prevalence of overweight was in Eastern Mediterranean (n = 9, 37.2%, 95% CI: 33.1%-41.4%) and that of obesity was in South-East Asia (n = 5, 26.4%, 95% CI: 5.3%-69.9%). NOS classification, NOS scores, sample size and the year of data collected were not significant moderators.

CONCLUSIONS

This review indicated the global prevalence of overweight and obesity among nurses along with the differences between regions. Healthcare organisations and policymakers should appreciate this increased risk and improve working conditions and environments for nurses to better maintain their metabolic health.

PATIENT OR PUBLIC CONTRIBUTION

Not applicable as this is a systematic review.

REGISTRATION

PROSPERO (ref: CRD42023403785) https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=403785.

TWEETABLE ABSTRACT

High prevalence of overweight and obesity among nurses worldwide.

Subcutaneous adipose tissue circadian gene expression: Relationship with insulin sensitivity, obesity, and the effect of weight-reducing dietary intervention

OBJECTIVE

The circadian rhythms are controlled by the central clock in the hypothalamic suprachiasmatic nuclei and by the peripheral clocks in tissues, including adipose tissue. The adipose tissue circadian clock may be associated with the regulation of insulin action; however, human data are limited. The aim of this study was to analyze the expression of subcutaneous adipose tissue circadian genes as they relate to obesity and insulin sensitivity before and after diet-induced weight loss.

METHODS

The study group comprised 38 individuals who were overweight or obese. The individuals completed a 12-wk dietary intervention program. Hyperinsulinemic-euglycemic clamp and subcutaneous adipose tissue biopsy were performed before and after the program. Sixteen normal weight individuals were examined at baseline and served as a control group.

RESULTS

At baseline, individuals who were overweight/obese had lower adipose tissue expression of NR1D1, NR1D2, DBP, PER1, and PER2 than normal weight individuals. The expression of ARNTL, CLOCK, and CRY did not differ between the groups. A weight-reducing dietary intervention resulted in an increase in the expression of adipose tissue NR1D2 and DBP, which was positively related to insulin sensitivity both before (in the entire study group and in the subgroup of overweight/obese individuals) and after the dietary intervention.

CONCLUSIONS

Adipose tissue circadian gene expression is decreased in obesity and this decrease may be partially reversed by dietary intervention. Among circadian genes, NR1D2 and DBP seem to be specifically associated with insulin action.

Associations of meal timing, number of eating occasions and night-time fasting duration with incidence of type 2 diabetes in the NutriNet-Santé cohort

BACKGROUND

Food intake plays a pivotal role in regulating circadian rhythms, which modulate glucose and lipid homeostasis. However, studies investigating the association of meal timing and type 2 diabetes (T2D) incidence are lacking. The objective of this study was to investigate the longitudinal associations of meal timing, number of eating occasions and night-time fasting duration with incidence of T2D.

METHODS

In total, 103 312 adults [79% women, mean age at baseline = 42.7 (SD = 14.6)] from the NutriNet-Santé cohort (2009-21) were included. Participants' meal timings and frequency were assessed using repeated 24-h dietary records and averaged from the first 2 years of follow-up (5.7 records/participant). Associations of meal timing, number of eating occasions and night-time fasting duration with incidence of T2D were assessed by using multivariable Cox proportional hazard models adjusted for known risk factors.

RESULTS

During a median follow-up of 7.3 years, 963 new cases of T2D were ascertained. Compared with participants habitually having a first meal before 8AM, those eating after 9AM had a higher incidence of T2D (HR = 1.59, 95% CI 1.30-1.94). Time of last meal was not associated with T2D incidence. Each additional eating episode was associated with a lower incidence of T2D (HR = 0.95, 95% CI 0.90-0.99). Night-time fasting duration was not associated with T2D incidence, except in participants having breakfast before 8AM and fasting for >13 h overnight (HR = 0.47, 95% CI 0.27-0.82).

CONCLUSIONS

In this large prospective study, a later first meal was associated with a higher incidence of T2D. If confirmed in other large-scale studies, an early breakfast should be considered in preventing T2D.

Circadian misalignment in obesity: The role for time-restricted feeding

BACKGROUND AND AIMS

The epidemic of obesity is associated with a substantial, complex and escalating burden of disease. Dietary and lifestyle interventions provide the mainstay of management; however, obesity is multifactorial and challenging to address clinically. Disrupted circadian behaviours, including late eating, are associated with obesity. Time-restricted feeding (TRF), the confinement of calorie intake to a temporal 'eating window', has received growing interest as a weight-loss intervention. Benefits are purported to arise from the fasting period and strengthened circadian metabolism. However, the current evidence-base for TRF is small-scale, limited, and there has been little evaluation of circadian schedule. This research aims to enable evidence-based conclusions regarding circadian-aligned TRF as a weight-loss intervention in obesity.

METHODS

A systematic three-tranche search strategy was conducted within PubMed. Included studies were critically evaluated. Search tranches scoped: interventional evidence for TRF; evidence linking meal timing, obesity and metabolic function; and evidence linking circadian function, obesity, and dysmetabolism. Results were summarised in a narrative analysis.

RESULTS

A total of 30 studies were included. From small-scale and short-term evidence, TRF was consistently associated with improved weight, glycaemic and anthropometric outcomes versus baseline or control. Good adherence and safety, and consistency of results between studies, were notable. Earlier ('circadian-aligned') eating was associated with greater diet-induced thermogenesis, and improved weight loss and glycaemic outcomes. Limited evidence suggested meaningful correlations between circadian clock function and obesity/metabolic risk.

CONCLUSIONS

Circadian-aligned TRF may present a promising intervention for weight loss and metabolic benefits in obese/overweight individuals.

Can omega-3 fatty acids and vitamin E co-supplementation affect obesity indices?

Background: Studies have shown that vitamin E as an antioxidant protects omega-3 fatty acids (FAs) from oxidation. Several studies have evaluated the effect of omega-3 FAs and vitamin E co-supplementation on obesity indices; however, the results are inconsistent. The present systematic review and meta-analysis was conducted to address the role of omega-3 FAs plus vitamin E on obesity indices. Methods: Cochrane Library, PubMed, Scopus, Embase, and Web of Science databases were searched up to February 2022. Among all of the qualified studies, 10 articles were selected. The effect size was presented as weighted mean difference (WMD) and 95% confidence interval (CI). Fixed-effects model was employed to perform meta-analysis. Subgroup analysis and publication bias assessment were carried out. Results: Ten eligible randomized controlled trials comprising 558 participants were included. The average dose of omega-3 FAs and vitamin E co-supplementation in studies was 1000-4000 mg/day and 400 IU, respectively. Intervention duration varied from 6 to 16 weeks. There was no significant effect of omega-3 and vitamin E co-supplementation on body weight (BW) (WMD=0.14 kg; 95% CI: -0.13 to 0.42; p=0.297), and body mass index (BMI) (WMD=0.08, 95% CI: -0.01 to 0.16, p=0.073). However, subgroup analysis showed that it might increase BMI in women over 50 years and if the intervention lasted more than 8 weeks. Conclusion: There was no significant impact of combined omega-3 FAs and vitamin E supplementation on BW and BMI; however, it should be noted that the intervention has an increasing impact when supplementation duration was >8 weeks and in individuals with type 2 diabetes mellitus, >50 years old, and BMI>25 kg/m2.

Sleep-Body Composition Relationship: Roles of Sleep Behaviors in General and Abdominal Obesity in Chinese Adolescents Aged 17-22 Years

This study aimed to investigate the association between sleep behaviors and body composition, which was measured by bioelectrical impedance analysis (BIA) among Chinese adolescents. Overall, 444 students (65.3% females, 19.12 ± 1.177 years) completed questionnaires describing sleep characteristics. Sleep characteristics were derived from subjective means. Body composition was obtained from BIA by InBody 720 (Biospace Co. Ltd., Seoul, Republic of Korea). Regression models tested relationships between sleep and body composition after adjustment for covariates. Students with weekday nap duration (>30 min/d) exerted higher waist-height ratio (WHtR) (B = 0.013, FDR-corrected p = 0.080). Average sleep duration (≤7 h/d) was linked to more WHtR (B = 0.016, FDR-corrected p = 0.080). People with high social jetlag showed gained visceral fat area (B = 7.475), WHtR (B = 0.015), waist to hip ratio (B = 0.012), fat mass index (B = 0.663) and body fat percentage (B = 1.703) (all FDR-corrected p < 0.1). Individuals with screen time before sleep (>0.5 h) exhibited higher visceral fat area (B = 7.934, FDR-corrected p = 0.064), WHtR (B = 0.017, FDR-corrected p = 0.080), waist to hip ratio (B = 0.016, FDR-corrected p = 0.090), fat mass index (B = 0.902, FDR-corrected p = 0.069) and body fat percentage (B = 2.892, FDR-corrected p = 0.018). We found poor sleep characteristics were closely related to general and abdominal obesity.

A qualitative exploration of the experiences of shift workers participated in a low-calorie meal replacement dietary intervention

OBJECTIVES

Shift work is associated with various health challenges, including obesity and metabolic disturbances. To address these concerns, a randomised controlled clinical trial was conducted to evaluate the efficacy of a low-calorie meal replacement (MR) dietary intervention for dinner among shift workers with obesity. This study focuses on the qualitative aspects of this intervention, aiming to explore the experiences and perceptions of shift workers who participated in the trial.

DESIGN

Following the completion of the intervention, semi-structured face-to-face or telephone interviews were conducted with a purposive sample of trial participants. Data analysis was inductive, thematic using NVivo V.10 software.

SETTING

The intervention was conducted among shift workers with obesity in a private hospital in Sri Lanka and resulted in a modest decrease in weight.

PARTICIPANTS

Using purposeful maximum variation sampling, we recruited eight healthcare shift workers who took part in a weight loss intervention.

RESULTS

All participants expressed satisfaction with the MR meal for dinner, highlighting its positive impact on their well-being. Despite initial difficulties, strong determination and motivation by results supported adherence. Some participants suggested that the MR could be improved with sweeter taste and more flavour options. Few reported mild bloating at the beginning, but no serious side effects were noted. Participants felt lighter in their bodies due to weight loss. The method's simplicity was the most frequently reported benefit, making it feasible even during busy night shifts. Overall, participants highly recommended the intervention to others in need.

CONCLUSION

Participants experienced weight loss by replacing their dinner with the MR. This study offers valuable insights for tailoring future workplace-based dietary interventions for this vulnerable population.

TRIAL REGISTRATION NUMBER

ACTRN12622000231741.

Evaluation of the "Shifting Weight using Intermittent Fasting in night-shift workers" weight loss interventions: a mixed-methods protocol

Introduction

Shift workers are at a greater risk for obesity-related conditions. The impacts of working at night presents a challenge for designing effective dietary weight-loss interventions for this population group. The Shifting Weight using Intermittent Fasting in night-shift workers (SWIFt) study is a world-first, randomized controlled trial that compares three weight-loss interventions. While the trial will evaluate the effectiveness of weight-loss outcomes, this mixed-methods evaluation aims to explore for who weight-loss outcomes are achieved and what factors (intervention features, individual, social, organisational and wider environmental) contribute to this.

Methods

A convergent, mixed-methods evaluation design was chosen where quantitative and qualitative data collection occurs concurrently, analyzed separately, and converged in a final synthesis. Quantitative measures include participant engagement assessed via: dietary consult attendance, fulfillment of dietary goals, dietary energy intake, adherence to self-monitoring, and rates for participant drop-out; analyzed for frequency and proportions. Regression models will determine associations between engagement measures, participant characteristics (sex, age, ethnicity, occupation, shift type, night-shifts per week, years in night shift), intervention group, and weight change. Qualitative measures include semi-structured interviews with participants at baseline, 24-weeks, and 18-months, and fortnightly audio-diaries during the 24-week intervention. Interviews/diaries will be transcribed verbatim and analyzed using five-step thematic framework analysis in NVivo. Results from the quantitative and qualitative data will be integrated via table and narrative form to interrogate the validity of conclusions.

Discussion

The SWIFt study is a world-first trial that compares the effectiveness of three weight-loss interventions for night shift workers. This mixed-methods evaluation aims to further explore the effectiveness of the interventions. The evaluation will determine for who the SWIFt interventions work best for, what intervention features are important, and what external factors need to be addressed to strengthen an approach. The findings will be useful for tailoring future scalability of dietary weight-loss interventions for night-shift workers.Clinical trial registration: This evaluation is based on the SWIFt trial registered with the Australian New Zealand Clinical Trials Registry [ACTRN 12619001035112].

Associations of multiple sleep dimensions with overall and abdominal obesity among children and adolescents: a population-based cross-sectional study

BACKGROUND

The relationship of insufficient sleep with the increased risk of obesity has been reported, but less is known about other sleep dimensions in the sleep-obesity associations.

OBJECTIVES

To assess the associations of multiple sleep dimensions with overall and abdominal obesity among Chinese students.

METHODS

This was a cross-sectional study involving 10,686 Han students aged 9-18 from Chinese National Survey on Students' Constitution and Health (CNSSCH). We collected sex, age, regions, parental educational levels, physical activity duration and sleep-related information by questionnaire survey, and also conducted anthropometric measurements including height, weight and waist circumference (WC). Unadjusted and adjusted binary logistic regression models were used to estimate the associations of sleep-related dimensions with obesity-related indicators.

RESULTS

Short sleep duration was associated with higher body mass index (BMI), larger WC and higher waist-to-height ratio (WHtR) in 9-12 and 16-18 age groups, whereas prolonged sleep duration on weekday was associated with higher BMI in 13-15 age group. Non-habitual midday napping and midday napping ≤0.5 h/d (vs 0.5 to 1 h/d) increased the risk of higher BMI in 13-15 age group, and the former was also associated with larger WC in 9-12 age group. Late bedtime was associated with larger WC and higher WHtR in 9-12 age group and with higher BMI and WHtR in 13-15 age group. Students aged 9-12 with social jet lag ≥2 h were found to have greater BMI after adjustment (Odds Ratio: 1.421; 95% confidence interval: 1.066-1.894).

CONCLUSIONS

Short or overlong sleep duration, late bedtime and great social jet lag were associated with higher prevalence of overall or abdominal obesity, while moderate midday napping can effectively decrease the risk. Those findings may assist in developing preventive strategies to combat obesity epidemic.

Circadian misalignment increases 24-hour acylated ghrelin in chronic shift workers: a randomized crossover trial

OBJECTIVE

Shift workers typically experience misalignment between their circadian system and behavioral/environmental cycles and have an increased risk for obesity. Experimental studies in non-shift workers have suggested that circadian misalignment can disrupt energy balance regulation. This study examined the impact of circadian misalignment in the most relevant population, i.e., chronic shift workers.

METHODS

Seven healthy chronic night shift workers underwent a randomized crossover study with two 3-day laboratory protocols: a night work protocol including 12-hour inverted behavioral/environmental cycles (circadian misalignment) and a day work protocol (circadian alignment).

RESULTS

Circadian misalignment led to a ~17% increase in 24-hour acylated ghrelin levels in the chronic shift workers (p = 0.009). Consistently, circadian misalignment resulted in ~14% higher hunger at breakfast in the night shift (p = 0.04). Circadian misalignment did not significantly change fasting and postprandial energy expenditure or respiratory exchange ratio (all p > 0.32). Unexpectedly, 24-hour behavioral activity levels were ~38% higher (p < 0.0001) during circadian misalignment, despite a concurrent increase in sleepiness (p = 0.03).

CONCLUSIONS

These results reveal that circadian misalignment, while carefully controlling for dietary intake, increases acylated ghrelin in chronic shift workers. Further studies should test whether the observed acute effects of circadian misalignment in chronic shift workers contribute to their increased obesity risk in the long term.

Overweight and obesity in adulthood, sociodemographic factors, lifestyle, and the early burden of noncommunicable diseases among Americans: NHANES 2007-2018

OBJECTIVES

To evaluate the association between nutritional status in early adulthood and the burden of noncommunicable diseases (NCDs); To evaluate the influence of sociodemographic factors and lifestyle on the outcomes of BMI kg/m2  ≤24.9, ≥25.0, and ≥30.0; to estimate the population attributable fraction (PAF) to BMI elevated at 25 years old in the burden of NCDs in American adults.

METHODS

We used data from 15 721 American adults participating in the National Health and Nutrition Examination Survey from 2007 to 2018. The Hazard Ratio (HR), Incidence Rate Ratio (IRR), and 95% confidence intervals (CI) were estimated in the proportional risk regression models of Cox (entire population) and Poisson (restricted to non-patients), respectively. The proportionality of the risk between the burden of NCDs and BMI at 25 years old was drawn by the Kaplan-Meier curve, and the PAF was calculated. All analyses were adjusted taking into account the sample weights.

RESULTS

Health disparities (sex, age, race/ethnicity, education, poverty index, and education level), and lifestyle (physical activity, smoking, and alcohol consumption) influenced the current nutritional status. Cumulative survival in overweight and obese groups decreased considerably over time (p < .0001). Being overweight and obese in adulthood may increase the risk of early NCDs (HR: 1.68, 95% CI: 1.54-1.84 and HR: 2.87, 95% CI: 2.56-3.21, respectively). About 22.72% (95% CI: 19.99-25.36, p < .001) of the burden NCDs could have been avoided if overweight at age 25 had been prevented.

CONCLUSIONS

Monitoring weight change from young adulthood can provide a sensitive and useful clinical measure for early detection of adverse trends in NCDs risk.

Circadian control of Nocturnin and its regulatory role in health and disease

Circadian rhythms are generated by intrinsic 24-h oscillations that anticipate the extrinsic changes associated with solar day. A conserved transcriptional-translational feedback loop generates these molecular oscillations of clock genes at the organismal and the cellular levels. One of the recently discovered outputs of circadian clock is Nocturnin (Noct) or Ccrn4l. In mice, Noct mRNA is broadly expressed in cells throughout the body, with a particularly high-amplitude rhythm in liver. NOCT belongs to the EEP family of proteins with the closest similarity to the CCR4 family of deadenylases. Multiple studies have investigated the role of Nocturnin in development, adipogenesis, lipid metabolism, inflammation, osteogenesis, and obesity. Further, mice lacking Noct (Noct KO or Noct-/-) are protected from high-fat diet-induced obesity and hepatic steatosis. Recent studies had provided new insights by investigating various aspects of Nocturnin, ranging from its sub-cellular localization to identification of its target transcripts. However, a profound understanding of its molecular function remains elusive. This review article seeks to integrate the available literature into our current understanding of the functions of Nocturnin, their regulatory roles in key tissues and to throw light on the existing scientific lacunae.

Time-restricted feeding attenuates hypercholesterolaemia and atherosclerosis development during circadian disturbance in APOE∗3-Leiden.CETP mice

BACKGROUND

Circadian disturbance (CD) is the consequence of a mismatch between endogenous circadian rhythms, behaviour, and/or environmental cycles, and frequently occurs during shift work. Shift work has been associated with elevated risk for atherosclerotic cardiovascular disease (asCVD) in humans, but evidence for the effectiveness of prevention strategies is lacking.

METHODS

Here, we applied time-restricted feeding (TRF) as a strategy to counteract atherosclerosis development during CD in female APOE∗3-Leiden.CETP mice, a well-established model for humanized lipoprotein metabolism. Control groups were subjected to a fixed 12:12 h light-dark cycle, while CD groups were subjected to 6-h phase advancement every 3 days. Groups had either ad libitum (AL) access to food or were subjected to TRF with restricted food access to the dark phase.

FINDINGS

TRF did not prevent the increase in the relative abundance of circulating inflammatory monocytes and elevation of (postprandial) plasma triglycerides during CD. Nonetheless, TRF reduced atherosclerotic lesion size and prevented an elevation in macrophage content of atherosclerotic lesions during CD, while it increased the relative abundance of anti-inflammatory monocytes, prevented activation of T cells, and lowered plasma total cholesterol levels and markers of hepatic cholesterol synthesis. These effects were independent of total food intake.

INTERPRETATION

We propose that time restricted eating could be a promising strategy for the primary prevention of asCVD risk in shift workers, which warrants future study in humans.

FUNDING

This work was funded by the Novo Nordisk Foundation, the Netherlands Ministry of Social Affairs and Employment, Amsterdam Cardiovascular Sciences, and the Dutch Heart Foundation.

Obesity, Chronic Stress, and Stress Reduction

The obesity epidemic is caused by the misalignment between human biology and the modern food environment, which has led to unhealthy eating patterns and behaviors and an increase in metabolic diseases. This has been caused by the shift from a "leptogenic" to an "obesogenic" food environment, characterized by the availability of unhealthy food and the ability to eat at any time of day due to advances in technology. Binge Eating Disorder (BED) is the most commonly diagnosed eating disorder, characterized by recurrent episodes of binge eating and a sense of loss of control over eating, and is treated with cognitive-behavioral therapy-enhanced (CBT-E). Shift work, especially night shift work, can disrupt the body's natural circadian rhythms and increase the risk of obesity and other negative health consequences, such as cardiovascular disease and metabolic syndrome. One dietary approach to address circadian dysregulation is time-restricted eating (TRE), which involves restricting food intake to specific periods of the day to synchronize the body's internal clock with the external environment. TRE has been found to cause modest weight loss and improve metabolic outcomes such as insulin sensitivity and blood pressure, but the extent to which it is beneficial may depend on adherence and other factors such as caloric restriction.

Association between matched chronotype and poor mental health among shift workers: a systematic review and meta-analysis

BACKGROUND

Nearly 0.7 billion workers are involved in the shift work system, leading to concerns about its potential impacts on the large-scale population mental health. This study aimed to synthesise evidence of the associations between matched chronotype and the risk of poor mental health among shift workers.

METHODS

Six computerised databases were searched from inception to September 2022. Observational studies were selected if they reported any association between common mental health parameters and chronotype scores/types of shift workers. The Preferred Reporting Items for Systematic Reviews and Meta-analyses checklist was followed. We extracted adjusted risk estimates to calculate pooled effect sizes and explore sources of heterogeneity. The study was registered in PROSPERO: CRD42022357437.

RESULTS

Fourteen studies including 49 909 workers were identified. Ever shift workers had a higher risk of poor mental health than the day workers (pooled OR 1.15, 95% CI 1.03 to 1.28; I²=14%, p=0.29), with the evening chronotype ever shift workers having a 1.47 times higher risk than those who worked during the day (pooled OR 1.47, 95% CI 1.13 to 1.91; I²=42%, p=0.16). Sensitivity analysis excluding studies with the highest risk of bias of each group demonstrated consistent findings.

CONCLUSIONS

Evening chronotype ever shift workers have poorer mental health than shift workers with other chronotypes. Chronotype remains unrecognised in the contemporary rostering system, making it a hidden contributor to occupational mental health. Work-related physical and mental stresses may be prevented/mitigated with further investigation on optimising shift work schedule combined with individual chronotype preference.

Effectiveness of worksite wellness programs based on physical activity to improve workers' health and productivity: a systematic review

BACKGROUND

Although the scientific literature has previously described the impact of worksite programs based on physical activity (WPPAs) on employees' productivity and health in different contexts, the effect of these programs has not been analyzed based on the characteristics or modalities of physical activity (PA) performed (e.g., aerobic exercise, strength training, flexibility). In addition, studies on WPPAs usually report health and productivity outcomes separately, not integrated into a single study. Knowing the health and economic-related impacts of a WPPAs could provide useful information for stakeholders and policy development.

OBJECTIVE

The purpose of this review was as follows: (1) to analyze the effect of different modalities of WPPAs on employees' productivity and health and (2) to investigate the economic impact of WPPAs.

METHODS

This systematic review is registered in PROSPERO (CRD42021230626) and complies with PRISMA guidelines. Only randomized controlled trials from 1997 to March 2021 were included. Two reviewers independently screened abstracts and full texts for study eligibility, extracted the data, and performed a quality assessment using the Cochrane Collaboration Risk-of-Bias Tool for randomized trials. Population, instruments, comparison, and outcome (PICO) elements were used to define eligibility criteria. Eight-hundred sixty relevant studies were found through electronic searches in PubMed, Web of Science, Medline, Scopus, and SPORTDiscus databases. Once the eligibility criteria were applied, a total of 16 papers were included.

RESULTS

Workability was the productivity variable most positively impacted by WPPAs. Cardiorespiratory fitness, muscle strength, and musculoskeletal symptoms health variables improved in all the studies included. It was not possible to fully examine the effectiveness of each exercise modality because of the heterogeneity in methodology, duration, and working population. Finally, cost-effectiveness could not be analyzed because this information was not reported in most studies.

CONCLUSION

All types of WPPAs analyzed improved workers' productivity and health. However, the heterogeneity of WPPAs does not allow to identify which modality is more effective.

The association of night shift work with the risk of all-cause dementia and Alzheimer's disease: a longitudinal study of 245,570 UK Biobank participants

BACKGROUND

The purpose of this research was to investigate a possible link between night shift work and the development of all-cause dementia and Alzheimer's disease (AD), as well as determine the contribution of night shift work, genetic susceptibility to AD.

METHODS

This study was conducted using the UK Biobank database. 245,570 participants with a mean follow-up length of 13.1 years were included. A Cox proportional hazards model was used to investigate the link between night shift work and the development of all-cause dementia or AD.

RESULTS

We counted a total of 1248 participants with all-cause dementia. In the final multivariable adjusted model, the risk of dementia was highest in always night shift workers (HR 1.465, 95% CI 1.058-2.028, P = 0.022), followed by irregular shift workers (HR 1.197, 95% CI 1.026-1.396, P = 0.023). AD events were recorded in 474 participants during the follow-up period. After final multivariate adjustment of model, always night shift workers remained at the highest risk (HR 2.031, 95% CI 1.269-3.250, P = 0.003). Moreover, always night shift workers were associated with a higher risk of AD in both low, intermediate and high AD-GRS groups.

CONCLUSIONS

Always night shift work had a higher risk of developing all-cause dementia and AD. Irregular shift workers had a higher risk of developing all-cause dementia than no shift workers. Always night shift work had a higher AD risk, regardless of whether they had a high, intermediate or low AD-GRS.

Gender and Nightshift Work: A Cross Sectional Study on Sleep Quality and Daytime Somnolence

A few studies suggested that female nightshift workers suffer more frequently from sleep deprivation and insomnia. We conducted a cross-sectional survey in two different occupational settings to address gender-related differences in nightshift work adaptation. We used the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index questionnaires to quantify daytime sleepiness and sleep quality among 156 workers, 91 from a ceramic tile factory and 65 healthcare workers, including hospital doctors, nurses, and nurse assistants. Seventy-three percent of participants (40 women and 74 men) were engaged in nightshift work. We used logistic regression analysis to predict daytime sleepiness and poor sleep quality as a function of personal and lifestyle variables and nightshift work. The female gender showed a strong association with both daytime sleepiness and poor sleep quality. Results were also suggestive of an increase in the risk of daytime sleepiness associated with nightshift work and being married. Our results confirm that women are especially vulnerable to sleep disruption. Promoting adaptation to nightshift work requires special attention towards gender issues.

Relationship Between Rotating Night Shift Work and Anthropometric Markers of Overall and Central Adiposity

Purpose

This study aimed to investigate possible association between rotating night shift (RNS) work and anthropometric markers of overall and central adiposity among male workers.

Methods

Medical records of workers who underwent medical examination at the Occupational Medicine Unit affiliated with Alexandria Faculty of Medicine were reviewed in December 2021 to extract data about RNS, overall adiposity [body mass index (BMI) from 25 to 29.9 kg/m² indicated overweight, while BMI ≥30 kg/m² indicated obesity], central adiposity (waist circumference ≥94 cm). Univariate and multivariate logistic regression were done to model adiposity as a function of potential demographic, lifestyle, and occupational factors.

Results

Data of 647 male workers, including daytime workers (26.9%) and RNS workers (73.1%) who spent 1-5 years, 6-9 years, or ≥10 years working RNS, were analyzed. No association was found between RNS work and overall adiposity (BMI ≥30 kg/m²). In multivariate regression, age, residence, and smoking status were predictors of an increased BMI. Compared with young workers (<30 years old), the odds of an increased BMI (BMI ≥25 kg/m²) were 2.6 and 3.01 times higher among workers who were 30-<40, and 40-<50 years old, respectively [95% CI=(1.35, 5.05) and (1.19, 7.56), respectively]. Workers who lived in urban areas were less likely to have had an increased BMI (OR=0.34, 95% CI=0.16, 0.74). The odds of an increased BMI were 2.14 times higher in workers who never smoked compared with current smokers (95% CI=1.12, 4.11). No association was found between RNS and central adiposity. In multivariate regression, age was the sole predictor of central adiposity.

Conclusion

The study supports the idea that RNS work might not be associated with overall or central adiposity and highlights a possible association between central adiposity and age and association between BMI and age, residence, and smoking behavior. Longitudinal, larger studies are required to explore the relationship between RNS and adiposity.

Influence of fasting during the night shift on next day eating behavior, hunger, and glucose and insulin levels: a randomized, three-condition, crossover trial

AIMS

To investigate the influence of fasting during the night shift on eating behavior, hunger, glucose and insulin levels the following day.

METHODS

Study with 10 male police officers who have been working at night. Participants were tested under three different conditions separated by at least 6 days of washout in a randomized, crossover design: "Night Shift Fasting" (NSF)-two nights of fasting during the night shift; "Night Shift Eating" (NSE)-two nights with the consumption of a standardized meal during the night shift (678 ± 42 kcal consumed at ~ 0200 h); and "Nighttime Sleep" (NS)-two nights of sleep. The morning after, blood glucose and insulin and hunger ratings were assessed, and food intake was assessed with an ad libitum test meal. Food intake was also assessed throughout the remainder of the day using a food record. Generalized Estimating Equations were used to analyze the effect of experimental condition.

RESULTS

Food intake during the test meal, especially of proteins and fats, was higher after fasting during the night shift compared to the other conditions (p < 0.05), whereas desire to eat scores were lower after the NSF compared to NSE condition (p = 0.043). Hunger levels were lower after the NSF compared to the NS condition (p = 0.012). Insulin and HOMA-IR were also lower in the morning after NSF (p < 0.001).

CONCLUSION

Fasting during the night shift leads to not only a higher intake of energy and macronutrients both in the early morning after work and throughout the next day, but also lower insulin levels and HOMA-IR in the morning.

REGISTRATION NUMBER OF CLINICAL TRIAL

NCT03800732. Initial release: 01/09/2019. Last release: 02/23/2022.

Relationship of long working hours and night shift working hours with incident diabetes: a retrospective cohort study in Taiwan

PURPOSE

The relationship among long working hours, night shift working hours, and diabetes is still unclear. We aimed to evaluate the association of long working hours and night shift working hours with diabetes among health care workers.

METHODS

We conducted a retrospective cohort study among health care workers in a tertiary medical center in Taiwan from 2002 to 2019. We compared the risk of diabetes among tertiles of total working hours (35-41, 42-45, and ≥46 h per week) and evaluated the relationship between long working hours and diabetes risk. We divided participants into three work patterns: day work only, evening shift workers, and night shift workers. In night shift workers, we further evaluated night shift working hours and incident diabetes using tertiles of night shift working hours (<17, 17-45, and ≥46 h per month). We estimated hazard ratios and 95% confidence intervals for incident diabetes using multivariable Cox proportional hazards models.

RESULTS

The study included 7081 participants. There were 301 incident cases of diabetes during 52,454 person-years. The adjusted hazard ratio (95% confidence interval) for participants who worked greater than or equal to 46 working hours per week was 3.45 (1.27, 9.39) compared with those who worked 35-41 hours. Compared with night shift workers who worked less than 17 h, the adjusted hazard ratios (95% confidence interval) for those who worked 17-45 and ≥46 night shift working hours per month were 2.26 (1.08, 4.75) and 2.60 (1.27, 5.33), respectively.

CONCLUSIONS

Long working hours and night shift working hours increased the risk of diabetes.

Shift work disorder, mental health and burnout among nurses: A cross-sectional study

AIM

The aim of the study was to examine the relationships among nurses' shift work disorder, mental health and burnout to inform efforts to alleviate shift work disorder.

DESIGN

This cross-sectional study was conducted in China using a web-based platform for questionnaire.

METHODS

The study was comprised of a convenience sample of 1,268 Registered Nurses from 21 public hospitals in mainland China from June 2019-July 2019. Participants completed a web-based survey designed to collect demographic and other self-reported data. An independent sample t test and Pearson correlation were performed to analyse the relationship between shift work disorder, mental health and burnout.

RESULTS

The vast majority (98.2%) of the participants were women between the ages of 20-59 years. The participants exhibited a higher incidence of mental health problems (58.1%) and burnout (65.5%) and those with shift work disorder exhibited a higher risk of mental health problems and burnout than those who did not have shift work disorder. Our research demonstrated that shift work disorder, combined with other variables, accounted for 40.5% of the variance in mental health (R²  = .405, adjusted R²  = .401, F = 107.214, p < .001) and 36.5% in burnout (R²  = .365, adjusted R²  = .361, F = 90.323, p < .001). Moreover, burnout negatively regulated the relationship between shift work disorder and mental health.

CONCLUSION

High-risk nurses with shift work disorder were at a much higher risk of mental health problems and burnout.

Associations between circadian disruption and cardiometabolic disease risk: A review

The human circadian system plays a vital role in many physiological processes, and circadian rhythms are found in virtually all tissues and organs. The disruption of circadian rhythms may lead to adverse health outcomes. Evidence from recent population-based studies was reviewed because they represent real-world behavior and can be useful in developing future studies to reduce the risk of adverse health conditions, including cardiovascular diseases, obesity, and diabetes mellitus, which may occur because of circadian disruption. An electronic search in PubMed and Web of Science (2012-2022) was performed. Selected articles were based on specific inclusion and exclusion criteria. Five factors that may disrupt circadian rhythm alignment are discussed: shift work, late chronotype, late sleep timing, sleep irregularity, and late meal timing. Evidence from observational studies of these circadian disruptors suggests potential detrimental effects on cardiometabolic health, including higher BMI/obesity, higher blood pressure, greater dyslipidemia, greater inflammation, and diabetes. Future research should identify the specific underlying pathways in order to mitigate the health consequences of shift work. Furthermore, optimal sleep and mealtimes for metabolic health can be explored in intervention studies. Lastly, it is important that the timing of external environmental cues (such as light) and behaviors that influence circadian rhythms are managed.

Validation of the Entrainment Signal Regularity Index and associations with children's changes in BMI

OBJECTIVE

This study examined the validity of a novel metric of circadian health, the Entrainment Signal Regularity Index (ESRI), and its relationship to changes in BMI during the school year and summer.

METHODS

In a longitudinal observational data set, this study examined the relationship between ESRI score and children's (n = 119, 5- to 8-year-olds) sleep and physical activity levels during the school year and summer, differences in ESRI score during the school year and summer, and the association of ESRI score during the school year and summer with changes in BMI across those time periods.

RESULTS

The ESRI score was higher during the school year (0.70 ± 0.10) compared with summer (0.63 ± 0.11); t(111) = 5.484, p < 0.001. Whereas the ESRI score at the beginning of the school year did not significantly predict BMI change during the school year (β = 0.05 ± 0.09 SE, p = 0.57), having a higher ESRI score during summer predicted smaller increases in BMI during summer (β = -0.22 ± 0.10 SE, p = 0.03).

CONCLUSIONS

Overall, children demonstrated higher entrainment regularity during the school year compared with the summer. During summer, having a higher entrainment signal was associated with smaller changes in summertime BMI. This effect was independent of the effects of children's sleep midpoint, sleep regularity, and physical activity on children's BMI.

The influence of six polymorphisms of uncoupling protein 3 (UCP3) gene and childhood obesity: a case-control study

BACKGROUND

Obesity is defined as a multifactorial disease, marked by excessive accumulation of body fat, responsible for compromising the individual's health over the years. The energy balance is essential for the proper functioning of the body, as the individual needs to earn and spend energy in a compensatory way. Mitochondrial Uncoupling Proteins (UCP) help in energy expenditure through heat release and genetic polymorphisms could be responsible for reducing energy consumption to release heat and consequently generate an excessive accumulation of fat in the body. Thus, this study aimed to investigate the potential association between six UCP3 polymorphisms, that have not yet been represented in ClinVar®, and pediatric obesity susceptibility.

METHODS

A case-control study was conducted with 225 children from Central Brazil. The groups were subdivided into obese (123) and eutrophic (102) individuals. The polymorphisms rs15763, rs1685354, rs1800849, rs11235972, rs647126, and rs3781907 were determined by real-time Polymerase Chain Reaction (qPCR).

RESULTS

Biochemical and anthropometric evaluation of obese group showed higher levels of triglycerides, insulin resistance, and LDL-C and low level of HDL-C. Insulin resistance, age, sex, HDL-C, fasting glucose, triglyceride levels, and parents' BMI explained up to 50% of body mass deposition in the studied population. Additionally, obese mothers contribute 2 × more to the Z-BMI of their children than the fathers. The SNP rs647126 contributed to 20% to the risk of obesity in children and the SNP rs3781907 contribute to 10%. Mutant alleles of UCP3 increase the risk for triglycerides, total cholesterol, and HDL-C levels. The polymorphism rs3781907 is the only one that could not be a biomarker for obesity as the risk allele seem to be protective gains the increase in Z-BMI in our pediatric population. Haplotype analysis demonstrated two SNP blocks (rs15763, rs647126, and rs1685534) and (rs11235972 and rs1800849) that showed linkage disequilibrium, with LOD 76.3% and D' = 0.96 and LOD 57.4% and D' = 0.97, respectively.

CONCLUSIONS

The causality between UCP3 polymorphism and obesity were not detected. On the other hand, the studied polymorphism contributes to Z-BMI, HOMA-IR, triglycerides, total cholesterol, and HDL-C levels. Haplotypes are concordant with the obese phenotype and contribute minimally to the risk of obesity.

"Mars Bar and a Tin of Red Bull Kept Me and My Patients Alive": Exploring Barriers to Healthy Eating through Facebook Comments of Shiftworkers

The negative impact of an unhealthy diet on the shiftworker population has been well-documented. However, little evidence exists on the underlying reasons for unhealthy eating behaviours and the existing barriers to healthy eating withinshiftwork environments. This qualitative study investigated the dietary behaviours reported by shiftworkers through Facebook comments. Comments were collected if they were on public shiftworker-relevant posts pertaining to dietary news or dietary information on Facebook and were posted by self-identified shiftworkers, relatives of shiftworkers, or partners of shiftworkers. A thematic analysis of the 144 comments collected generated four categories that can be used to understand the motivations for eating behaviour on-shift: what shiftworkers eat, where food is sourced from, when food is eaten, and why certain foods are chosen. Results reveal motivations, attitudes, and both internal and external barriers to healthy eating behaviours, as well as similarities and differences across shiftwork industries. Recommendations for future research include further explorations on the link between scheduled eating (e.g., time-restricted eating) and shiftwork, the impact of a rotating shift arrangements on dietary health behaviours, and the impact of interpersonal relationships on shiftworker dietary choices. Understanding these motivations will inform strategies to promote healthy eating and help understand barriers for shiftworkers.

Circadian Rhythms Disrupted by Light at Night and Mistimed Food Intake Alter Hormonal Rhythms and Metabolism

Availability of artificial light and light-emitting devices have altered human temporal life, allowing 24-hour healthcare, commerce and production, and expanding social life around the clock. However, physiology and behavior that evolved in the context of 24 h solar days are frequently perturbed by exposure to artificial light at night. This is particularly salient in the context of circadian rhythms, the result of endogenous biological clocks with a rhythm of ~24 h. Circadian rhythms govern the temporal features of physiology and behavior, and are set to precisely 24 h primarily by exposure to light during the solar day, though other factors, such as the timing of meals, can also affect circadian rhythms. Circadian rhythms are significantly affected by night shift work because of exposure to nocturnal light, electronic devices, and shifts in the timing of meals. Night shift workers are at increased risk for metabolic disorder, as well as several types of cancer. Others who are exposed to artificial light at night or late mealtimes also show disrupted circadian rhythms and increased metabolic and cardiac disorders. It is imperative to understand how disrupted circadian rhythms alter metabolic function to develop strategies to mitigate their negative effects. In this review, we provide an introduction to circadian rhythms, physiological regulation of homeostasis by the suprachiasmatic nucleus (SCN), and SCN-mediated hormones that display circadian rhythms, including melatonin and glucocorticoids. Next, we discuss circadian-gated physiological processes including sleep and food intake, followed by types of disrupted circadian rhythms and how modern lighting disrupts molecular clock rhythms. Lastly, we identify how disruptions to hormones and metabolism can increase susceptibility to metabolic syndrome and risk for cardiovascular diseases, and discuss various strategies to mitigate the harmful consequences associated with disrupted circadian rhythms on human health.

The Effect of Night Shifts on 24-h Rhythms in the Urinary Metabolome of Police Officers on a Rotating Work Schedule

Shift workers face an increased risk of metabolic health problems, but the direct metabolic response to working nights is not fully understood. The aim of this study was to investigate the effect of night shifts on the 24-h urinary metabolome of shift workers. Eleven police officers working rotating shifts completed two 24-h laboratory visits that took place before and after they worked 7 consecutive nights. Sleep and meals were scheduled on a day schedule in the first visit and then on a night schedule (i.e., sleep and meals shifted by approximately 12 h) in the second visit. Targeted metabolomic analysis was performed on urine samples collected throughout these laboratory visits. Differential rhythmicity analysis was used to compare 24-h rhythms in urinary metabolites in both conditions. Our results show that on the day schedule, 24-h rhythms are present in the urinary levels of the majority of metabolites, but that this is significantly reduced on the night schedule, partly due to loss of organic acid rhythmicity. Furthermore, misalignment of 24-h metabolite rhythms with the shifted behavioral cycles in the night schedule was observed in more than half of the metabolites that were rhythmic in both conditions (all acylcarnitines). These results show that working nights alters the daily rhythms of the urinary metabolome in rotating shift workers, with the most notable impact observed for acylcarnitines and organic acids, 2 metabolite classes involved in mitochondrial function. Further research is warranted to study how these changes relate to the increased metabolic risks associated with shift work.

Outdoor artificial light at night and human health: A review of epidemiological studies

We conducted a non-systematic review of epidemiological studies on a potential link between exposure to outdoor artificial light at night (O-ALAN) and disease occurrence in humans published since 2009. In recent years, a number of presses have been published on this issue, but the conclusions have been mixed. We therefore decided to critically analyze the available epidemiological evidence of such a correlation. After a careful search, 51 studies were identified and included in the review. They addressed the potential link between O-ALAN exposure and the incidence of breast cancer, other cancers, sleep and circadian rhythm disorders, obesity and cardiovascular diseases, mental disorders, infectious diseases, and complications during pregnancy and childbirth. The vast majority of papers revealed the existence of such a link. However, the amount of epidemiological evidence supporting the correlation across groups of disorders varied widely. In addition, we found that all papers contained at least one of the following omissions: lack of the temporal and spatial resolution in light at night measurements, measuring only light intensity without considering its wavelength, and not accounting for many important confounding factors in their statistical analyses. Therefore, we believe that the link between O-ALAN exposure and the occurrence of the disorders in question suggested by the authors of the reviewed papers may be in some cases at least to some extent, a coincidence. Further epidemiological studies, free of significant omissions highlighted in this paper, are needed.

Circadian disruption impairs glucose homeostasis in male but not in female mice and is dependent on gonadal sex hormones

Circadian disruption (CD) is the consequence of a mismatch between endogenous circadian rhythms and behavior, and frequently occurs in shift workers. CD has often been linked to impairment of glucose and lipid homeostasis. It is, however, unknown if these effects are sex dependent. Here, we subjected male and female C57BL/6J mice to 6-h light phase advancements every 3 days to induce CD and assessed glucose and lipid homeostasis. Within this model, we studied the involvement of gonadal sex hormones by injecting mice with gonadotropin-releasing hormone-antagonist degarelix. We demonstrate that CD has sex-specific effects on glucose homeostasis, as CD elevated fasting insulin levels in male mice while increasing fasting glucose levels in female mice, which appeared to be independent of behavior, food intake, and energy expenditure. Absence of gonadal sex hormones lowered plasma insulin levels in male mice subjected to CD while it delayed glucose clearance in female mice subjected to CD. CD elevated plasma triglyceride (TG) levels and delayed plasma clearance of TG-rich lipoproteins in both sexes, coinciding with reduced TG-derived FA uptake by adipose tissues. Absence of gonadal sex hormones did not notably alter the effects of CD on lipid metabolism. We conclude that CD causes sex-dependent effects on glucose metabolism, as aggravated by male gonadal sex hormones and partly rescued by female gonadal sex hormones. Future studies on CD should consider the inclusion of both sexes, which may eventually contribute to personalized advice for shift workers.

Primary Prevention of Weight Gain Among New Bus Operators: Results of the "Success & Health Impacts For Transit operators during Onboarding" (SHIFT Onboard) Pilot Study

OBJECTIVE

This study aimed to test the feasibility and efficacy of an enhanced onboarding intervention to prevent weight gain and support the early job success of new bus operators.

METHODS

Control participants ( n = 9) completed usual practice new employee training and onboarding. Intervention participants ( n = 14) completed five supplemental trainings and four online challenges during their first year. Primary outcomes were body weight, dietary behaviors, physical activity, and sleep duration/quality. Early job success was evaluated with measures of newcomer adjustment.

RESULTS

The difference between intervention and control participants in body weight change at 12-month was -6.71 lb (Cohen's d = -1.35). Differences in health behavior changes were mixed, but newcomer adjustment changes favored the intervention group.

CONCLUSIONS

Results support the feasibility of enhanced onboarding for bus operators to prevent worsening health while simultaneously advancing their success as new employees.

Chrono-Nutrition: Circadian Rhythm and Personalized Nutrition

The human circadian system has a period of approximately 24 h and studies on the consequences of "chornodisruption" have greatly expanded. Lifestyle and environmental factors of modern societies (i.e., artificial lighting, jetlag, shift work, and around-the-clock access to energy-dense food) can induce disruptions of the circadian system and thereby adversely affect individual health. Growing evidence demonstrates a complex reciprocal relationship between metabolism and the circadian system, in which perturbations in one system affect the other one. From a nutritional genomics perspective, genetic variants in clock genes can both influence metabolic health and modify the individual response to diet. Moreover, an interplay between the circadian rhythm, gut microbiome, and epigenome has been demonstrated, with the diet in turn able to modulate this complex link suggesting a remarkable plasticity of the underlying mechanisms. In this view, the study of the impact of the timing of eating by matching elements from nutritional research with chrono-biology, that is, chrono-nutrition, could have significant implications for personalized nutrition in terms of reducing the prevalence and burden of chronic diseases. This review provides an overview of the current evidence on the interactions between the circadian system and nutrition, highlighting how this link could in turn influence the epigenome and microbiome. In addition, possible nutritional strategies to manage circadian-aligned feeding are suggested.

Evaluation of work conditions of nurses employed in a shift system in hospital wards during the COVID-19 pandemic

BACKGROUND

Nurses work in a shift system that determines the provision of round-the-clock care of a patient in hospital conditions; however, it entails health consequences.

OBJECTIVE

The aim of the study was the evaluation of work conditions of nurses engaged in shift work in hospital wards during the COVID-19 pandemic.

METHODS

The study was conducted in 2020, and included 108 nurses working in a shift system in hospital wards. The research method was a diagnostic survey, using an author-constructed questionnaire.

RESULTS

88.9% nurses reported a negative effect of shift work on their physical health: 'musculoskeletal pain', 'elevated arterial blood pressure', and 'hormonal disorders' - 54.5% of respondents used pharmacological treatment. The causes of physical disorders were: 'microclimate', 'physical effort', 'noise', and 'forced body position'. Shift work exerted a negative effect on psychological health of the majority of respondents (75.0%): 'deconcentration', 'sleep disorders', 'feeling of occupational burnout' - treatment in 38.9% of respondents. Psychological health disorders were caused by: 'circadian rhythms disturbance by shift work', 'chronic stresses, and 'conflicts at work'. 69.7% of respondents reported that their shift work was disturbed by organizational factors, including: a 'badly planned work schedule', 'enhanced pace of work due to staff shortage', 'ambiguous division of duties, rights, responsibilities', 'shortages of equipment at the workplace'.

CONCLUSION

The examined nurses experienced a negative effect of shift work on their physical and psychological health which, for some of them, was the cause of pharmacological treatment. Many organizational factors hindered the work of nurses in a shift system in hospital wards.

Metabolomic profiles in night shift workers: A cross-sectional study on hospital female nurses

Background and aim

Shift work, especially including night shifts, has been found associated with several diseases, including obesity, diabetes, cancers, and cardiovascular, mental, gastrointestinal and sleep disorders. Metabolomics (an omics-based methodology) may shed light on early biological alterations underlying these associations. We thus aimed to evaluate the effect of night shift work (NSW) on serum metabolites in a sample of hospital female nurses.

Methods

We recruited 46 nurses currently working in NSW in Milan (Italy), matched to 51 colleagues not employed in night shifts. Participants filled in a questionnaire on demographics, lifestyle habits, personal and family health history and work, and donated a blood sample. The metabolome was evaluated through a validated targeted approach measuring 188 metabolites. Only metabolites with at least 50% observations above the detection limit were considered, after standardization and log-transformation. Associations between each metabolite and NSW were assessed applying Tobit regression models and Random Forest, a machine-learning algorithm.

Results

When comparing current vs. never night shifters, we observed lower levels of 21 glycerophospholipids and 6 sphingolipids, and higher levels of serotonin (+171.0%, 95%CI: 49.1-392.7), aspartic acid (+155.8%, 95%CI: 40.8-364.7), and taurine (+182.1%, 95%CI: 67.6-374.9). The latter was higher in former vs. never night shifters too (+208.8%, 95%CI: 69.2-463.3). Tobit regression comparing ever (i.e., current + former) and never night shifters returned similar results. Years worked in night shifts did not seem to affect metabolite levels. The Random-Forest algorithm confirmed taurine and aspartic acid among the most important variables in discriminating current vs. never night shifters.

Conclusions

This study, although based on a small sample size, shows altered levels of some metabolites in night shift workers. If confirmed, our results may shed light on early biological alterations that might be related to adverse health effects of NSW.

Association between different patterns of shift work and liver function tests: A cross-sectional analysis of Shahedieh PERSIAN cohort data, Iran, 2020

BACKGROUND

Recent studies suggest that shift work may cause liver dysfunction.

OBJECTIVE

This study aimed to examine the relationship between different patterns of shift work and elevated level of liver enzymes.

METHODS

In this cross-sectional study, 1910 workers aged 35 to 70 years were selected with simple random sampling from 9978 participants of the recruitment phase of Shahedieh PERSIAN cohort study. Level of serum liver enzymes (ALT, AST, ALP, and GGT) and ALT/AST ratio was compared between shift workers and non-shift workers, and among employees working in different patterns of shift work. Data were analyzed by SPSS (version 21.0) using Student's T test, Mann-Whitney U test, chi-square test, Kruskal Wallis test, and logistic regression.

RESULTS

Among 1347 males (71%) and 563 females (29%) with a mean age of 40.4±7.4 years, 469 were shift workers. Fixed evening type shift was the most common (30.3%) and fixed night-shift was the least common (0.9%) type of shift work. The mean blood levels of liver enzymes was not significantly different between shift workers and non-shift workers. In comparison between different patterns of shift work, the mean serum level of GGT was significantly higher in individuals with slow rotating shifts than those with fixed evening shifts, rapid rotating, split and fixed 24 hour shifts (p≤0.001). After adjusting for confounding factors only elevated AST was significantly higher in shift workers.

CONCLUSION

There was only a significant association between shift work and elevated AST, and no relationship was found with ALT, ALP, GGT, and ALT/AST ratio.

Using a Motivational Paradigm to Develop an Exercise Program for Nurses with High Risk of Metabolic Syndrome

Nurses are frontline care providers whose health is vital to providing good quality of care to patients. The purpose of this study was to develop an exercise program for high-risk metabolic syndrome nurses based on the transtheoretical model. The transtheoretical model was used in this study due to its popular use in exercise behavior change and it can clearly identify the stage of exercise so as to plan an effective program to promote health. This was a quasi-experimental pilot study with a total of 40 participants who met the inclusion criteria. Exercise programs were developed for three groups distinguished by their commitment to exercising for health. Sixteen (40%) nurses moved one step forward, six (15%) nurses moved backward, and eighteen (45%) nurses maintained at the same stage over time (stable sedentary, 40%; stable active, 5%). Bowker’s test of symmetry, χ2 = 14.00 (p < 0.01), revealed that the population exercising increased significantly after the intervention. After the program, the perceived benefits from exercise in the decisional balance significantly increased to 1.53 (t = 2.223, p < 0.05), perceived exercise barriers significantly decreased to 3.10 (t = −3.075, p < 0.05), and self-efficacy significantly increased to 2.90 (t = 3.251, p < 0.01), respectively. Applying the transtheoretical model to health behavior enables significant change. The benefits of applying the transtheoretical model for promoting exercise include increasing perceived exercise benefits and self-efficacy, decreasing perceived exercise barriers, and increasing physical activity levels.

What do we know about the effect of night-shift work on cardiovascular risk factors? An umbrella review

Objective

To evaluate the existing evidence on the effect of night-shift work and its subtypes (permanent and rotating) on cardiovascular risk factors: diabetes, lipid disorders, being overweight, hypertension, smoking habits, sedentariness, and occupational psychosocial stressors.

Method

A Web of Sciences and Cochrane review library search was conducted to identify systematic reviews with or without meta-analysis dealing with the quantification of the link between night-shift work and the studied cardiovascular risk factors in working populations. We used the AMSTAR 2 to evaluate the quality of each review. The main results of the included systematic reviews were compiled in a summary structured around the different cardiovascular risk factors.

Results

After selection, 33 systematic reviews were included: nine for diabetes, four for lipid disorders, nine for being overweight, four for hypertension, two for smoking habits, three for occupational psychosocial stressors and two for sedentariness. The results confirmed an excess risk of diabetes of about 10% regardless of the type of night work. A stated excess risk of being overweight at around 25% was also highlighted for shift workers overall, which could reach 38% among night-shift workers. An increased risk of obesity, estimated at 5% for night-shift workers and at 18% for rotating shift workers, was observed. An excess risk of hypertension was estimated at around 30% when considering the broad definition of shift work and when night periods were included in rotating shifts. The literature provided inconsistent results for the link between lipid disorders and night-shift work. Shift workers appeared to be more likely to smoke. The link between shift work and occupational psychosocial stressors was scarcely explored in the available studies. Sedentariness was scarcely considered in systematic reviews, which prevents any firm conclusions.

Conclusion

The consequences of night work in terms of diabetes, being overweight/obesity and hypertension are established. Monitoring of these cardiovascular risk factors for these night-shift workers could be implemented by practitioners. In contrast, the links with lipid disorders, sedentariness, smoking habits, and occupational psychosocial stressors warrant further investigation.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021275212, PROSPERO (ID CRD42021275212).

Oral health outcomes and shift working among male workers: A cross-sectional survey

Working time outside routine daily working hours is known as shift working. Studies have shown adverse effects of shift working such as stress, obesity, and diabetes on the workers' health. The aim of the present study was to compare aspects of oral health in shift workers and non-shift workers of a cement factory in Shahroud, Iran. Study population comprised of 180 male workers of the factory in the year 2015. Convenience sampling was continued until recruiting 180 subjects of shift- and non-shift workers. Data collection included oral health questionnaire, health and safety executive (HSE) questionnaire, and clinical oral examination. The Chi-square test, Pearson correlation coefficient, and generalized Poisson model were employed for statistical evaluation. Mean age of the workers was 39.19 (±9.48); 53% had educational level of less than diploma. Their mean DMFT was 12.89 (±5.75) which correlated with number of years in shift work schedule (Pearson correlation coefficient: 0.41; p<0.001) but not correlated with job stress (Pearson correlation coefficient: -0.11; p = 0.12). Mean number of deep periodontal pockets among the workers was 5.03 (±1.84) that showed correlation with number of years in shift work schedule (Pearson correlation coefficient: 0.33; p<0.001) but no correlation with job stress (Pearson correlation coefficient: -0.03; p = 0.68). Adherence to various oral health behaviors was reported by less than half of the workers. Positive correlation of dental caries and periodontal diseases with shift working partly signals negative impact of working conditions on oral health among this group of workers which calls for modifications in their working environment to facilitate health practices.

Meal replacement as a weight loss strategy for night shift workers with obesity: a protocol for a randomized controlled trial

BACKGROUND

Shift work is considered a risk factor for a number of chronic health conditions including obesity. Weight reduction in obese patients lowers the risk for cardiovascular disease, diabetes, certain cancers, and mortality. Achieving a negative energy balance by providing low-calorie meal replacements is widely used for weight management. This study aims to evaluate the impact of a low-calorie "meal-replacement" on the weight and metabolic parameters of shift workers with obesity.

METHODS

This trial will be conducted in a parallel, randomized controlled design for a period of 8 weeks. A total of 44 shift workers with body mass index over 25 kg/m² will be recruited after assessing eligibility. Participants will be randomly assigned to the test and control groups on a 1:1 ratio. The intervention group (N = 22) will be provided with a low-calorie (~200 kcal) meal replacement shake as dinner, and the control group (N = 22) will continue their habitual diets. The visits and the evaluations will be done as follows: screening (visit 0), 4 weeks (visit 1), and 8 weeks (visit 2). Anthropometric measurements will be taken at 0, 4, and 8 weeks. Body composition, biochemical parameters, dietary intake, and physical activity will be assessed during the first and the last visit.

OUTCOMES

The primary outcome will be the proportion of participants that had a 5% body weight loss from baseline. The secondary outcomes will be post-intervention changes in other metabolic parameters.

DISCUSSION

To our knowledge, this is one of the first randomized controlled trials evaluating the effects of a meal replacement as the night meal for weight loss in shift workers with obesity. Moreover, improvement of metabolic parameters in shift workers will be an added benefit to this high-risk group.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12622000231741 . Registered on 09 February 2022.

Shift work and the risk for metabolic syndrome among healthcare workers: A systematic review and meta-analysis

Shift work, defined as work occurring outside typical daytime working hours, is associated with an increased risk for metabolic syndrome (MetS) due to several biological and environmental changes. The MetS refers to the clustering of several known cardiovascular risk factors, including insulin resistance, obesity, dyslipidemia, and hypertension. This systematic review aims to evaluate the literature on the association between shift work and the risk of MetS in employees of the health sector. A systematic search was conducted in PubMed, Web of Science, and Scopus databases using appropriate keywords for studies published before September 1, 2021. Eligible studies were those that compared the prevalence of MetS between day and shift healthcare workers; had a cross-sectional, case-control, or cohort study design; provided sufficient data for calculating odds ratios or relative risks with 95% confidence intervals; and articles in English. The Joanna Briggs Institute prevalence critical appraisal tool was used for quality analysis. Risk for MetS and related measures of effect size were retrieved from studies for meta-analysis. Twelve studies met the criteria for inclusion in the review and meta-analysis. Sample sizes ranged from 42 to 738, and the age range of subjects was between 18 and 65 years. Ten studies demonstrated high methodological quality, while two studies were of average quality. Ten out of 12 studies in the review demonstrated a higher risk in shift workers for developing MetS than day workers. The pooled OR of MetS in shift workers based on 12 studies was 2.17 (95% CI = 1.31-3.60, P = 0.003; I²  = 82%, P < 0.001). Shift workers exhibited more than a twofold increase in the chance of developing MetS in comparison with day workers.

Shift workers’ perceptions and experiences of adhering to a nutrition intervention at night whilst working: a qualitative study

This study explored the feasibility of implementing a meal timing intervention during night shift work. Data were collected via semi-structured interviews. Interviews were coded inductively by two researchers independently, then three major themes were collaboratively developed. Subthemes from each major theme were mapped to the theoretical domains framework and the Capability Opportunity Motivation model of behaviour change. Seventeen night shift workers (rotating or permanent) aged between 25 and 65 years were interviewed. Participants predominately worked as health professionals. The feasibility of a simple meal timing intervention to avoid eating between 1 and 6 am on night shift is largely affected by three major influences (1) physical and emotional burden of shift work which drives food temptations; (2) the workplace context including the meal break environment, social and cultural context at work, and break scheduling; and (3) motivation of the individual. Facilitators to avoiding eating at night were, keeping busy, having co-worker support, management support, education of health benefits and/or belief that the intervention was health promoting. The barriers to avoiding eating at night were the emotional and physical toll of working at night leading to comfort eating and not having rest areas away from food environments. To support night shift workers with changing timing of meals, interventions at work should target both individual and organisational level behaviour change.