Permanent Night Shift Research Articles

Association of night shift work and biological ageing: the mediating role of body mass index.

We aimed to examine whether current and lifetime night shift work is associated with accelerated biological ageing and the potential role of body mass index (BMI) in mediating the association. Data were sourced from the UK Biobank cohort. This study included participants who reported detailed information on their current work schedule and had complete data to calculate PhenoAge. The outcome of interest was biological ageing, measured by PhenoAge acceleration. Multivariable linear regression models were conducted to test the relationship between night shift work and biological ageing. Mediation analyses were performed. Of the 182064 participants included, the mean age was 52.6years, and 51.1% were male. After adjustment for chronological age and sex, compared with day workers, shift workers without night shift, irregular night shift workers and permanent night shift workers were associated with 0.59-, 0.87- and 1.30-year increase in biological ageing, respectively (P for trend <.001). Considering the lifetime work schedule, participants who worked night shifts >10years and participants who worked >8 night shifts each month showed increased biological age acceleration [>10years: β = 0.54, 95% confidence interval (CI) 0.29-0.79; >8 times/month: β = 0.29, 95% CI 0.07-0.50]. The mediation analysis showed that BMI mediated the associations between night shift work and biological age acceleration by 36%-53%. We showed that night shift work was associated with accelerated biological ageing. Our findings highlight the interventions on appropriate shift work schedules and weight management in night shift workers, which may slow the biological ageing process and ultimately reduce the burden of age-related diseases.

Sex differences in patients with acute myocardial infarction under 65 years of age: a Spanish cohort

Abstract Background Myocardial infarction (MI) clinical presentation and prognosis usually vary between men and women. Studying different age groups may be of interest. Aim Compare clinical characteristics and prognosis between men and women under 65 years old (y/o) with MI. Methods observational prospective study, including all patients admitted for MI between 2016 and 2023. Median follow-up was 43months[20-71]. Results Out of a total of 1064 patients, 436 were younger than 65 y/o (98 were women and 338 were men). The median age was similar in both sexes: 53.4[41-65] vs 54.2[43-65], p=0.24. A higher percentage of men were married (76.6 vs 59.2%, p&amp;lt;0.01), while a greater proportion of women were widowed (7.9 vs 1.3%, p&amp;lt;0.01). Men showed higher rates of permanent employment (71.4vs54.9%, p=0.01) and night shifts (58vs26.1%, p&amp;lt;0.01), whereas women had a higher unemployment rate (26.8vs15.2%, p=0.03) and reported higher levels of stress (70.3 vs 42.4%, p&amp;lt;0.01). The percentage of smokers was similar in both sexes (84.6% in men vs 75.8% in women, p=0.06), but there were more cocaine users in the male group (10.8vs1.4%, p=0.01). Women had a higher prevalence of autoimmune diseases (20.4 vs 6.2%, p&amp;lt;0.01), allergies (17.3 vs 5.6%, p&amp;lt;0.01), psychiatric illnesses (25.8 vs 9.9%, p&amp;lt;0.01), and migraines (15.6 vs 1.8%, p&amp;lt;0.01). Men had more history of previous coronary angioplasty (9.5 vs 3.1%, p=0.05). At admission, men presented with higher levels of creatine kinase (1175.2±1490.1 vs 766.5±1084.5 U/L, p=0.02), haemoglobin (15.2±1.6 vs 14±1.4 g/dl, p&amp;lt;0.01) and serum creatinine (1.2±1.4 vs 0.8±0.5 mg/dl, p&amp;lt;0.01), while women exhibited higher cholesterol levels (186.5±51.6 vs 174.9±44.5 mg/dl, p=0.03). Coronary dissection and myocardial infarction with non-obstructive coronary arteries were more frequent in women (14.3 vs 2.1%, p&amp;lt;0.01 and 27.6 vs 11.5%, p&amp;lt;0.01, respectively). Women also underwent additional tests at a higher rate, such as cardiac magnetic resonance (14.3 vs 4%, p&amp;lt;0.01) and vasospasm test (7.6vs1.9%, p=0.02). During hospitalization, men underwent drug-eluting stent implantation more frequently (66.7vs23.8%, p&amp;lt;0.01). At discharge, they were more likely to receive antiplateles (93.7vs84.5%, p&amp;lt;0.01), beta-blockers (81.7vs.71.1%, p=0.03), angiotensin-converting enzyme inhibitors (63.2vs49.5%, p=0.02) and statins (96.4vs84.5%, p&amp;lt;0.01). The rest of variables, which showed no significant differences, are in Table 1. Prognosis was similar in both sexes: death from any cause (HR 0.7, 95%CI[0.1-3.4]), cardiovascular readmission (HR 1.2, 95%CI[0.5-2.7]), reinfarction (HR 1.9, 95%CI[0.3-10.3]), stroke (HR 1, 95%CI[0.1-11.9]). Conclusion The clinical profile of men and women with MI is clearly different. The investigation into the underlying mechanisms of MI occasionally necessitates more extensive testing in women. Additionally, the treatment plans at discharge diverge between the two genders. Nevertheless, the prognosis appears to be similar for both sexes.

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

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

12-week melatonin administration had no effect on diabetes risk markers and fat intake in overweight women night workers.

Interactions between circadian clocks and key mediators of chronic low-grade inflammation associated with fat consumption may be important in maintaining metabolic homeostasis and may pose a risk for the development of obesity-associated comorbidities, especially type 2 diabetes (T2DM). The aims of the present study were to evaluate the effects of melatonin administration on diabetes risk markers according to dietary lipid profile (pro-inflammatory versus anti-inflammatory) in excessive weight night workers, and to determine the effect of administration on fat consumption profile. A randomized, controlled, double-blind, crossover clinical trial involving 27 nursing professionals working permanent night shifts under a 12×36-hour system. The melatonin group (12 weeks) used synthetic melatonin (3 mg) only on days off and between shifts, while the placebo group (12 weeks) was instructed to take a placebo, also on days off and between shifts. For inflammatory characteristics, participants were divided into pro-inflammatory (saturated fats, trans fats and cholesterol) and anti-inflammatory (monounsaturated, polyunsaturated fats and EPA + DHA) groups according to fatty acid determinations. At baseline and at the end of each phase, blood glucose, insulin, glycosylated hemoglobin plasma concentrations were collected, and HOMA-IR was calculated. Melatonin administration for 12 weeks had no effect on T2DM risk markers according to dietary lipid profile (pro-inflammatory or anti-inflammatory potential) in excessive weight night workers. Among the limitations of the study include the fact that the low dose may have influenced the results expected in the hypothesis, and individual adaptations to night work were not evaluated. The insights discussed are important for future research investigating the influence of melatonin and fats considered anti- or pro-inflammatory on glucose and insulin homeostasis related to night work.

Associations between long-term night shift work and incidence of chronic obstructive pulmonary disease: a prospective cohort study of 277,059 UK Biobank participants

BackgroundLittle is known about the effects of night shifts and their interactions with genetic factors on chronic obstructive pulmonary disease (COPD). In this study, we aim to investigate relationships between long-term night shift work exposure and COPD risk, and assess modification effects of genetic predisposition.MethodsA total of 277,059 subjects who were in paid employment or self-employed were included in the UK Biobank. Information on current and lifetime employment was obtained, and a weighted COPD-specific genetic risk score (GRS) was constructed. We used Cox proportional hazard models to investigate associations between night shift work and COPD risk, and their interaction with COPD-specific GRS.ResultsThe cohort study included 277,059 participants (133,063 men [48.03%]; mean [SD] age, 52.71 [7.08] years). During a median follow-up of 12.87 years, we documented 6558 incidents of COPD. From day work, irregular night shifts to regular night shifts, there was an increased trend in COPD incidence (P for trend < 0.001). Compared with day workers, the hazard ratio (HR) and 95% confidence interval (CI) of COPD was 1.28 (1.20, 1.37) for subjects with rarely/sometimes night shifts and 1.49 (1.35, 1.66) for those with permanent night shifts. Besides, the longer durations (especially in subjects with night shifts ≥ 10 years) and increasing monthly frequency of night shifts (in workers with > 8 nights/month) were associated with a higher COPD risk. Additionally, there was an additive interaction between night shifts and genetic susceptibility on the COPD risk. Subjects with permanent night shifts and high genetic risk had the highest risk of COPD (HR: 1.90 [95% CI: 1.63, 2.22]), with day workers with low genetic risk as a reference.ConclusionsLong-term night shift exposure is associated with a higher risk of COPD. Our findings suggest that decreasing the frequency and duration of night shifts may offer a promising approach to mitigating respiratory disease incidence in night shift workers, particularly in light of individual susceptibility.

Shift work and evening chronotype are associated with hepatic fat fraction and non-alcoholic fatty liver disease in 282,303 UK biobank participants.

Non-alcoholic fatty liver disease (NAFLD) has rapidly become the most common liver disease worldwide. Modern lifestyles have been linked to this rise in prevalence with changes in rhythmic human behaviour emerging as a possible mechanism. We investigated how shift working patterns and chronotype were associated with hepatic fat fraction and NAFLD in 282,303 UK Biobank participants. We stratified participants into day, irregular-shift, and permanent night-shift workers. We then utilised multiple methods of disease identification including (i) Dallas steatosis index (DSI), (ii) ICD10 codes, and (iii) hepatic proton density fat fraction (PDFF) and examined how shift work exposure impacted these variables. We further assessed the relationship of baseline chronotype with liver phenotypes using these same outcome measures. Compared to day workers, irregular-shift workers were more likely to have a high DSI (OR 1.29 (1.2-1.4)) after adjusting for major covariates with some attenuation after additional adjustment for BMI (OR 1.12 (1.03-1.22)). Likelihood of high DSI was also increased in permanent night-shift workers (OR 1.08 (0.9-1.29)) in the fully adjusted model. Mediator analysis revealed that BMI was a significant mediator of the shift work effect. Compared to participants with intermediate chronotype, those with extreme late chronotype had a higher likelihood of high DSI defined NAFLD (OR 1.45 (1.34-1.56)) and a higher likelihood of NAFLD/NASH by ICD10 code (OR 1.23 (1.09-1.39)). Hepatic PDFF was elevated in irregular shift workers, but not permanent night-shift workers. Irregular-shift work and extreme late chronotype are associated with pathological liver fat accumulation, suggesting circadian misalignment may have an underlying pathogenic role. These findings have implications for health interventions to mitigate the detrimental effect of shift work.

Poor sleep and shift work associate with increased blood pressure and inflammation in UK Biobank participants

Disrupted circadian rhythms have been linked to an increased risk of hypertension and cardiovascular disease. However, many studies show inconsistent findings and are not sufficiently powered for targeted subgroup analyses. Using the UK Biobank cohort, we evaluate the association between circadian rhythm-disrupting behaviours, blood pressure (SBP, DBP) and inflammatory markers in >350,000 adults with European white British ancestry. The independent U-shaped relationship between sleep length and SBP/DBP is most prominent with a low inflammatory status. Poor sleep quality and permanent night shift work are also positively associated with SBP/DBP. Although fully adjusting for BMI in the linear regression model attenuated effect sizes, these associations remain significant. Two-sample Mendelian Randomisation (MR) analyses support a potential causal effect of long sleep, short sleep, chronotype, daytime napping and sleep duration on SBP/DBP. Thus, in the current study, we present a positive association between circadian rhythm-disrupting behaviours and SBP/DBP regulation in males and females that is largely independent of age.

Occupational and leisure-time physical activity and associated factors among shift-working registered nurses: A cross-sectional study

BackgroundLifestyle behaviors, including physical activity, may help to mitigate the chronic disease and mental health consequences of shift work in nurses at the individual level. The physical activity levels of shift-working nurses and factors that predict physical activity in this population are unclear. ObjectiveThe primary aim of this study was to describe work and leisure-time physical activity behaviors in shift-working hospital nurses and determine behavioral, biological, or work-related factors that influence physical activity. DesignObservational; cross-sectional. Setting(s)Acute care hospital system. ParticipantsCurrent registered nurses (N = 112) with a shift work schedule (rotating, mixed, or permanent night shift) MethodsOnline validated questionnaires were used to assess work and leisure physical activity levels (International Physical Activity Questionnaire); Theory of Planned Behavior constructs (attitudes, subjective norms, perceived behavioral control, and intention) related to physical activity; and morningness-eveningness. Work-related characteristics were also assessed. Structural equation models were examined for the Theory of Planned Behavior constructs. ResultsShift-working nurses reported 227 (±265) minutes/week of leisure-time and 566 (±868) minutes/week of occupational moderate-to-vigorous physical activity. Attitude (standardized coefficient = 0.63; p < 0.05) was the strongest predictor of physical activity intention, and intention (standardized coefficient = 0.40; p < 0.05) was a significant predictor of leisure-time physical activity behavior. There were no statistically significant differences in physical activity type and amount between those who identified as “morning”, “intermediate”, or “evening” types. Clinical nurse leaders engaged in statistically significantly less leisure-time physical activity than direct care nurses (703 ± 1142 vs. 1202 ± 1372 MET-minutes/week) (p = 0.013). ConclusionsOur findings suggest that on average, shift-working registered nurses report meeting national physical activity guidelines for leisure and occupational physical activity; however, there is considerable interindividual variability. Theory of Planned Behavior constructs, especially attitude and intention, were significantly associated with leisure-time physical activity but not occupational physical activity, emphasizing the importance of targeting them in interventions to increase physical activity levels among shift-working nurses.

The Associations of Chronotype and Shift Work With Rheumatoid Arthritis.

The circadian clock regulates multiple aspects of human physiology including immunity. People have a circadian preference termed chronotype. Those with an evening preference may be better suited to shift work, but also carry higher risk of adverse health. Shift work leads to misalignment of circadian rhythms and is associated with increased risk of inflammatory disease such as asthma and cancer. Here, we investigate the association between chronotype, shift work, and rheumatoid arthritis (RA). The associations between exposures of shift work and chronotype on risk of RA were studied in up to 444,210 U.K. Biobank participants. Multivariable logistic regression models were adjusted for covariates: age, sex, ethnicity, alcohol intake, smoking history, Townsend Deprivation Index (TDI), sleep duration, length of working week, and body mass index (BMI). After adjusting for covariates, individuals with a morning chronotype had lower odds of having rheumatoid arthritis (RA; odds ratio [OR]: 0.93, 95% confidence interval [CI]: 0.88-0.99) when compared to intermediate chronotypes. The association between morning chronotype and RA persisted with a more stringent RA case definition (covariate-adjusted OR: 0.89, 95% CI: 0.81-0.97). When adjusted for age, sex, ethnicity, and TDI, shift workers had higher odds of RA (OR: 1.22, 95% CI: 1.1-1.36) compared to day workers that attenuated to the null after further covariate adjustment (OR: 1.1, 95% CI: 0.98-1.22). Morning chronotypes working permanent night shifts had significantly higher odds of RA compared to day workers (OR: 1.89, 95% CI: 1.19-2.99). These data point to a role for circadian rhythms in RA pathogenesis. Further studies are required to determine the mechanisms underlying this association and understand the potential impact of shift work on chronic inflammatory disease and its mediating factors.

0246 Current shift work and frailty: findings from the UK Biobank

Abstract Introduction Shift work may disrupt sleep and circadian rhythms, leading to adverse health outcomes. The objective of this study is to examine whether performing shift work is associated with frailty in middle- to older-aged adults. Methods We examined current shift work exposure and frailty risk in 242,126 UK Biobank participants (38-71 years old; 128,595 females). Using the baseline self-reported employment information, participants were categorized as shift workers (with ‘work schedule that falls outside of the normal daytime working hours of 9am-5pm’) or day workers if no shift work schedule. Based on a previously validated approach, frailty phenotype was identified when three or more of the following five criteria were fulfilled: self-reported weight loss, exhaustion, low physical activity, slow walking pace, and measured low grip strength. Multivariate logistic regression models were used to assess the association between shift work and frailty. Results Among 242,126 participants, 201,489 (83.2%) were day workers and 40,637 (16.8%) shift workers. Frailty was identified in 4,308 participants (1.8%), including 3,312 day workers (1.6%) and 996 shift workers (2.5%). Compared with day workers, shift workers were at higher risk for frailty after adjusting age, sex, and ethnicity, i.e., odds ratio (OR) =1.58 [95% CI, 1.47-1.70] (p &amp;lt; 0.0001). The effect of shift work appeared to be more pronounced in 5,659 permanent night shift workers (OR = 1.98 [95% CI, 1.68-2.32], p &amp;lt; 0.0001). The differences between day workers and shift workers persisted even after further adjusting for social economic status, sleep duration, and chronotype (OR = 1.38 [95% CI, 1.28-1.48] for all shift workers; OR = 1.53 [95% CI, 1.30-1.80] for permanent night shift workers, both p values &amp;lt; 0.0001). Conclusion Middle- to older-aged adults who were currently performing shift work, especially those permanent night shift workers, were more likely to be frail. Longitudinal and interventional studies are warranted to elucidate the causal relationship between shift work and the risk of frailty. Support (if any) BrightFocus Foundation (A2020886S), NIH (RF1AG059867, RF1AG064312)

Shift work schedule and sleep patterns in relation to incident depression: Evidence from a prospective cohort study

This study aims to explore the joint associations of shift work and sleep patterns with incident depression. The present prospective cohort using data from UK biobank, included 220,651 participants aged 38 to 71 years recruited between 2006 and 2010. Every participant finished a self-completed touch-screen questionnaire. Hazards ratios (HRs) with corresponding 95% confidence intervals (CIs) of incident depression were reported for shift work and sleep patterns by Cox-proportional hazard models. The average follow-up time was 12.13±1.94 years and the incidence rate of depression was 2.95 (2.89–3.02) per 1000 person-years. After fully adjustment, the participants with irregular and permanent night shifts companied by any sleep pattern were significantly associated with increased risk of incident depression compared with no shift work companied by favorable sleep patterns. The females seemed to be more vulnerable when having night shifts and unfavorable sleep patterns compared with the males. The increased risk of incident depression associated with shift work regardless of night shifts and evening/weekend shifts was not able to offset by favorable sleep patterns. The workers with unhealthy sleep patterns, especially inappropriate sleep duration and insomnia companied by shift work schedule should be paid more attention considering higher risk of depression.

Evaluation of sleep quality and duration using wearable sensors in shift laborers of construction industry: A public health perspective.

Approximately 21% of the workers in developing and developed countries are shift laborers. The laborer's work shifts can affect personal life and sleep standards, adversely impacting laborers and their manage. This study assesses the impact of various shift plans (seven evenings/7 days, fixed-night or fixed-day, and backup shifts) on shift laborers, considering four shift schedules. Most laborers were on rotational shifts, whereas others were on a permanent day, permanent night, and standby shifts. In a cross-sectional study, 45 development laborers from the National Construction firm were enlisted. Bio-wearable sensors were provided to monitor sleep. Participants were approached and asked to complete a survey bundle comprising the Pittsburgh sleep quality index (PSQI) and Epworth sleepiness scale (ESS). Differences in sleep models were estimated using a Fitbit watch at various shift schedules. The average age of laborers who participated in the study was 37.5 years, and their average experience in the construction company was 6.5 years. The average total sleep time was 346 ± 46 min. The rotational shift laborers yielded the minimum total sleep time compared to the average PSQI and ESS scores of 7.66 ± 1.3 and 6.94 ± 3.4, respectively. Fifteen shift laborers (33.33%) were affected by a sleeping disorder in the present experimental investigation, and 30 participants had inadequate standards of sleep based on the PSQI scores. Poor sleep quality and duration among construction shift laborers decrease productivity at work. Additional studies are expected to assess sleep-related issues affecting construction shift laborers.

Effects of One Night of Forced Wakefulness on Morning Resting Blood Pressure in Humans: The Role of Biological Sex and Weight Status.

Permanent night shift work is associated with adverse health effects, including elevated blood pressure (BP) and hypertension. Here, we examined the BP response to one night of forced wakefulness in a sitting position in a cohort without night shift work experience. According to a counterbalanced crossover design, 47 young adults with either obesity (N = 22; 10 women) or normal weight (N = 25; 11 women) participated in one night of sleep and one night of forced wakefulness under in-laboratory conditions. Resting ankle and brachial arterial BP were assessed in the morning, i.e., the time of the day when adverse cardiovascular events peak. After forced wakefulness, diastolic and mean arterial BP were ~4 mmHg higher at the ankle site and ~3 mmHg higher at the brachial site than after regular sleep (p < 0.05). The increase in BP following overnight forced wakefulness was more pronounced among men vs. women and more significant for diastolic BP at both sites among participants with normal weight vs. those with obesity. If confirmed in larger cohorts, including 24 h BP monitoring, people with occupations involving night shifts might benefit from regular BP monitoring. Particular attention should be paid to possible sex- and weight-specific effects of night shift work on BP.

Night Shift Work, Genetic Risk, and Hypertension

ObjectiveTo perform a prospective cohort study to investigate whether night shift work is associated with incident hypertension and whether this association is modified by genetic susceptibility to hypertension because evidence on the association between night shift work and hypertension is insufficient. MethodsA total of 232,665 participants of UK Biobank who were recruited from 2006 to 2010 and observed to January 31, 2018, were included in this study. A Cox proportional hazards model with covariate adjustment was performed to assess the association between night shift work exposure and hypertension risk. We constructed a polygenic risk score (PRS) for genetic susceptibility to hypertension, which was used to explore whether genetic susceptibility to hypertension modified the effect of night shift work. The robustness of the results was assessed by sensitivity analysis. ResultsNight shift workers had a higher hypertension risk than day shift workers, which increased with increasing frequency of night shift work (Ptrend<.001). The association was attenuated but still remained statistically significant in the fully adjusted model. We explored the joint effect of night shift work and genetic susceptibility on hypertension. Permanent night shift workers with higher hypertension PRSs had higher risk of hypertension than day workers with low PRSs. ConclusionNight shift work exposure was associated with increased hypertension risk, which was modified by the genetic risk for hypertension, indicating that there is a joint effect of night shift work and genetic risk on hypertension.

The Effect of Exogenous Melatonin on Eating Habits of Female Night Workers with Excessive Weight.

Background and Aims: Melatonin is a pineal hormone that plays an important role as an endogenous synchronizer of circadian rhythms and energy metabolism. As this circadian component has been closely related to eating behavior, an important question on this topic would be whether melatonin administration could influence eating habits. However, this topic has been rarely studied in the literature in individuals with excessive weight and chronic circadian misalignment, such as shift workers. Therefore, the present study aims to evaluate the effects of exogenous melatonin administration on the quali/quantitative aspects and temporal distribution of food intake in female night workers with excessive weight (overweight and obesity). An additional aim is to evaluate the association of the referred outcomes with circadian misalignment and chronotype. Methods: A randomized, double-blind, placebo-controlled, crossover clinical trial was conducted with 27 female nursing professionals with excessive weight who worked permanent night shifts. The protocol was implemented under real-life conditions for 24 weeks, in two randomly allocated conditions (12 weeks of melatonin and 12 weeks of placebo). The quali/quantitative aspects of food intake (NOVA classification, total energy intake and the proportion of calories from macronutrients) and meal timing were assessed using food diaries. Timing for every meal recorded in the diaries was assessed to evaluate the temporal distribution of food intake. Generalized estimating equations were performed for each dependent variable. Results: No significant modifications in total energy intake, macronutrient distribution, types of foods consumed, and meal timing were observed after melatonin administration. Different levels of circadian misalignment and chronotype did not interfere with these results. Conclusion: Eating habits of female night workers with excessive weight remained unchanged after melatonin administration, and no association of these results with circadian misalignment and chronotype was found. These results suggest that the metabolic effects of melatonin may occur independently of food intake.

Night and shift work characteristics and incident ischemic heart disease and atrial fibrillation among healthcare employees - a prospective cohort study.

This study aimed to examine the effects of various aspects of night and shift work on the risk of incident ischemic heart disease (IHD) and atrial fibrillation (AF) using detailed and registry-based exposure data. This prospective cohort study included >30 300 healthcare employees (eg, nurses, nursing assistants) employed for at least one year in Region Stockholm 2008-2016. Information on daily working hours was obtained from a computerized administrative employee register and outcomes from national and regional registers. Using discrete-time proportional hazard models, we analyzed the outcomes as functions of working hour characteristics the preceding year, adjusted for sex, age, country of birth, education, and profession. We observed 223 cases of IHD and 281 cases of AF during follow-up 2009-2016. The risk of IHD was increased among employees who the preceding year had permanent night shifts compared to those with permanent day work [hazard ratio (HR) 1.61, 95% confidence interval (CI) 1.06-2.43] and among employees working night shifts >120 times per year compared to those who never worked night (HR 1.53, 95% CI 1.05-2.21). When restricted to non-night workers, the risk of IHD was increased for employees having frequent quick returns from afternoon shifts. No increased risks were observed for AF. Night work, especially working permanent night shifts and frequent night shifts, is associated with an increased risk of incident IHD but not AF. Moreover, frequent quick returns from afternoon shifts (among non-night workers) increased IHD risk. Organizing work schedules to minimize these exposures may reduce IHD risk.

Shift Work, Genetic Factors, and the Risk of Heart Failure: A Prospective Study of the UK Biobank

ObjectiveTo quantify the association of combined shift work and genetic factors with the incidence of heart failure (HF). Participants and MethodsThis study included 242,754 participants with complete shift work information in the UK Biobank. Participants were followed from baseline (2006 to 2010) through January 31, 2018. The association between shift work and HF incidence was investigated separately in males and females using a Cox proportional hazards model adjusted for covariates. In addition, we established a polygenic risk score and assessed whether shift work alters genetic susceptibility to HF. ResultsThe results showed a significant association of permanent night shift work with incident HF among females (hazard ratio, 2.25; 95% CI, 1.34 to 3.76; P=.002) after adjusting for age, and the association was attenuated in the fully adjusted model. Among men, we did not detect an association between shift work and HF. In addition, we observed that the association between the risk of HF and shift work was strengthened by high genetic risk. Permanent night shift work paired with high genetic risk, compared with low genetic risk, was suggested to be associated with the risk of HF in females (hazard ratio, 2.89; 95% CI, 1.05 to 7.94) but not in males. ConclusionShift work, particularly permanent night shift work, may increase the risk of HF in females, especially in those with high genetic risk.

Association of sleep disturbance with shift work, occupational stress, and musculoskeletal pain in Chinese public hospital emergency workers: A multicentre cross-sectional study

ABSTRACT Poor sleep, which is reportedly prevalent among healthcare professionals, could lead to various detrimental consequences. This study aimed to investigate the sleep quality of individuals working in emergency departments of public hospitals in China and explore the potential factors influencing sleep disturbance. A self-administered questionnaire was completed by 7688 emergency workers from 147 public hospitals in Shandong, China. Log-binomial regression analysis was performed to explore the relationship of sleep disturbance with possible influencing factors, including individual and work characteristics, occupational stress, shift work, and musculoskeletal pain. The participants’ mean Pittsburgh Sleep Quality Index score was 9.6 ± 4.8, with 5341 (69.5%, 68.2–70.7%) of them experiencing sleep disturbance. The sleep quality was poorer in doctors (10.2 ± 5.1, 71.0%, 69.0–73.0%) than in nurses (9.2 ± 4.5, 68.6%, 67.0–70.1%), and poorer in those working in secondary (9.9 ± 4.5, 70.2%, 68.0–72.3%) and tertiary (12.2 ± 4.9, 77.5%, 75.3–79.7%) hospitals than in primary hospitals (8.0 ± 4.1, 64.6%, 62.6–66.6%). High prevalence of sleep disturbance was significantly associated with shift work, occupational stress, musculoskeletal pain, fewer breaks in a work shift, and less exercise during leisure time, after adjusting for confounding variables. Sleep disturbance occurred in emergency workers in the following order: two-shift rotation > three-shift rotation > permanent night shift > permanent day shift. Emergency workers in public hospitals in China had poor sleep quality and commonly experienced musculoskeletal pain. Urgent and comprehensive measures are needed to combat these issues.

Impact of night and shift work on metabolic syndrome and its components: a cross-sectional study in an active middle-to-older-aged population-based sample

ObjectivesTo examine the effects of work schedules on metabolic syndrome and its components in active middle-to-older-aged workers.MethodsA cross-sectional analysis including middle-to-older-aged active workers from the population-based CoLaus|PsyCoLaus study (Lausanne, Switzerland)...

Social jetlag and sleep debts are altered in different rosters of night shift work

Night and shift work are suspected to cause various adverse effects on health and sleep. Sleep deprivation through shift work is assumed to be compensated on free days. So far it is not clear how different shift systems and shift lengths affect sleep structure on work and free days. Especially working night shifts disrupts the circadian rhythm but also extended working hours (12h) might affect sleep characteristics. Hitherto, the magnitude of sleep debt, social jetlag, and Locomotor Inactivity During Sleep (LIDS) in different shift systems is unknown. Here, we investigated the impact of five different shift rosters on sleep in 129 industrial workers from Germany. Permanent night work with multiple shift systems with and without night shifts and with different shift lengths were compared. Wrist-activity was monitored over 28 days revealing sleep on- and offsets as well as LIDS as proxy for sleep quality. Overall, 3,865 sleep bouts comprising 22,310 hours of sleep were examined. The mean daily age-adjusted sleep duration (including naps) was 6:43h and did not differ between shift workers of different rosters. However, sleep duration on workdays was particularly low in rotational shift systems with 12h-shifts (5:00h), while overall sleep debt was highest. Shift workers showed a median absolute social jetlag of 3:03h, which differed considerably between shift types and rosters (p<0.0001). Permanent night workers had the highest social jetlag (5:08h) and latest mid-sleeps on workdays and free days. Sleep quality was reduced in permanent night shift workers compared with shift workers in other rosters and differed between daytime and nighttime sleep. Shift work leads to partial sleep deprivation, which particularly affects workers in 12h-shifts and permanent night shifts. Working these shifts resulted in higher sleep debts and larger absolute social jetlag whereas sleep quality was especially reduced in permanent night shift workers compared with shift workers of other rosters.