Causal relationships of excessive daytime napping with atherosclerosis and cardiovascular diseases: a Mendelian randomization study

Causal Association of Sleep Traits with All-Cause and Cause-Specific Mortality: A Prospective Cohort and Mendelian Randomization Study

The study aimed to explore the association between different sleep traits and all-cause mortality as well as to validate causality in the association through mendelian randomization (MR). We analyzed 451,420 European ancestry participants from the UK Biobank. Multivariable-adjusted Cox proportional hazards model was conducted to evaluate the association between sleep traits and all-cause mortality. In MR analysis, the inverse variance weighting (IVW) method was applied as the primary analysis to investigate the causal association between sleep traits and mortality. During a median follow-up period of 12.68 years, 34,397 individuals died. Observational analyses showed the multivariate-adjusted hazard ratio (HR) and 95% confidence intervals (CIs) for short sleep, long sleep, early chronotype, daytime sleepiness, daytime napping, and insomnia with mortality, 1.246 (1.195, 1.298), 1.735 (1.643, 1.831), 0.931 (0.909, 0.953), 1.276 (1.212, 1.344), 1.299 (1.254, 1.346), and 1.117 (1.091, 1.142) (All p < 0.0001). Based on UK Biobank, MR analysis indicated the association between daytime napping and an increased risk of all-cause mortality (odd ratio [OR]: 1.219, 95% CI: 1.071-1.387, p = 0.003), which may be largely attributable to cancer disease mortality (OR: 1.188, 95% CI: 1.009-1.399, p = 0.039). We found no causal association between sleep duration, short sleep, long sleep, chronotype, daytime sleepiness, insomnia, and mortality risk. The causal associations between sleep traits and all-cause mortality risk were directionally replicated in FinnGen. Our findings suggest a potential causal association between daytime napping and increased risk of all-cause mortality in middle-aged and older persons. The finding could have important implications for evaluating daytime napping habits to decrease the risk of mortality.

Sleep and Cardiovascular Health

Sleep is recognized as a foundational pillar of health, essential for maintaining nearly all vital processes, and a crucial component of cardiovascular function. In recent years, there has been a paradigm shift to conceptualize sleep health as a combination of multiple domains, including duration, timing, quality, variability/regularity, habits/behaviors, and disordered sleep. This review provides a comprehensive overview of the current evidence linking the multifaceted elements that contribute to healthy sleep with cardiovascular and blood pressure-related outcomes. The reviewed literature indicates a strong relationship between sleep and cardiovascular health. However, the specific pathophysiological mechanisms that bridge the various dimensions of sleep with cardiovascular outcomes remain elusive. Given the global burden of cardiovascular disease, understanding the interplay between sleep and cardiovascular health has important implications for both individual and population health. Sustained efforts to move beyond a focus on discrete domains of sleep are essential to fully understand this complex and potentially bidirectional relationship. Promoting healthy sleep patterns and optimizing the management and treatment of sleep disorders are key steps toward developing more comprehensive strategies for reducing cardiovascular risk. Integrating sleep health into routine clinical care is identified as a critical opportunity to enhance cardiovascular disease prevention and management, particularly among vulnerable and high-risk populations.

Association of Sleep Duration With Incident Carotid Plaque: A Prospective Cohort Study

BACKGROUND

Sleep is an important determinant of cardiovascular health. We sought to investigate the longitudinal association between sleep duration and incident carotid plaque in a rural Chinese population.

METHODS

This population-based prospective cohort study included 1004 rural residents (age ≥40 years) who were free of carotid plaque and had no history of clinical stroke and transient ischemic attack at baseline (2017). Incident carotid plaques were detected by carotid ultrasound images at follow-up (2021). Multivariable Cox regression was used to associate sleep duration with the presence and severity of incident carotid plaques. Restricted cubic splines analyses were conducted to assess dose-response association between sleep duration and incident carotid plaques.

RESULTS

During the mean follow-up of 3.95 (SD=0.14) years, 214 (21.3%) of the 1004 participants were found to have incident carotid plaques. A short sleep duration (<7 versus 7-9 hours) was associated with multivariable-adjusted hazard ratio (95% CI) of 1.58 (1.10-2.28) for carotid plaques, 2.96 (1.38-6.36) for greater carotid plaque thickness, and 2.57 (1.33-4.97) for multiple carotid plaques; those associations remained significant in participants with low-to-intermediate traditional cardiovascular disease risk. Long sleep duration (>9 versus 7-9 hours) was not significantly associated with carotid plaques. Restricted cubic splines supported the association of short, but not long, sleep duration with increased risk of incident carotid plaques.

CONCLUSIONS

A short sleep duration is a risk factor for carotid plaques, even among individuals with low-to-intermediate cardiovascular disease risk. This suggests that short sleep duration may be a potential target for early interventions to delay carotid atherosclerosis.

REGISTRATION

URL: https://www.chictr.org.cn; Unique Identifier: ChiCTR1800017197.

Daytime napping and risk of incident main adverse cardiovascular events and mortality among adults with type 2 diabetes

AIMS

To explore the link between daytime napping and the risk of major adverse cardiovascular events (MACE) and mortality in individuals with type 2 diabetes.

METHODS

This prospective study included 21,129 participants with diabetes from the UK Biobank, all of whom were free of MACE and cancer at baseline. Data on habitual daytime napping and sleep duration were collected via a baseline questionnaire. Cox proportional hazards regression models were employed to assess the relationship between daytime napping and MACE, all-cause mortality, and cardiovascular disease (CVD) specific mortality. MACE was defined as a composite of myocardial infarction, heart failure, and stroke.

RESULTS

Over an average 11.9-year follow-up, 5,611 MACE cases, 3,854 all-cause deaths, and 1,839 CVD deaths were identified. Compared to those who never/rarely napped, the multivariable-adjusted hazard ratios for usually napping were: 1.39 (1.08, 1.65) for MACE; 1.44 (1.01, 1.92) for myocardial infarction; 1.33 (1.07, 1.64) for heart failure; 1.57 (1.06, 2.33) for stroke; 1.28 (1.01, 1.60) for all-cause mortality; 1.33 (0.97, 1.94) for CVD mortality.

CONCLUSIONS

Frequent daytime napping is significantly associated with an increased risk of MACE and mortality among individuals with diabetes, particularly those who have extended sleep durations of more than 10 h and severe diabetes.

Implications of Long Sleep Duration on Cardiovascular Health: A Systematic Review

Sleep duration is an important determinant of cardiovascular health, yet the adverse effects of long sleep duration remain underexplored. While short sleep has well-documented associations with increased cardiovascular risk, emerging evidence highlights a U-shaped relationship, with excessive sleep also linked to adverse outcomes. This systematic review evaluates the association between prolonged sleep duration and cardiovascular health outcomes, including coronary artery disease (CAD), stroke, myocardial infarction (MI), hypertension, heart failure (HF), and atherosclerosis. A systematic search of PubMed, Embase, and Web of Science identified 38 studies published between 2008 and 2024 that investigated the relationship between sleep duration and cardiovascular health. Prolonged sleep duration was consistently associated with increased risks of CAD, stroke (ischemic and hemorrhagic), hypertension, and MI. Elevated inflammatory markers, such as C-reactive protein (CRP) and interleukin-6 (IL-6), emerged as potential mediators alongside demographic and lifestyle factors, including age, gender, and socioeconomic status. Long sleep duration may serve as a modifiable risk factor for cardiovascular diseases. Incorporating sleep assessments into cardiovascular risk evaluations could inform prevention strategies, and further research is needed to elucidate mechanisms and develop targeted interventions.

Integrated bioinformatic analysis of the shared molecular mechanisms between ANCA-associated vasculitis and atherosclerosis

BACKGROUND AND OBJECTIVE

Accumulated evidence supports the tendency of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis(AAV) to coexist with atherosclerosis (AS). However, the common etiology of these two diseases remains unclear. This study aims to explore the mechanisms underlying the concurrent occurrence of ANCA and AS.

METHODS

Microarray data of AAV and AS were examined in a comprehensive gene expression database. Weighted gene co-expression network analysis (WGCNA) and differential gene expression analysis (GEO2R) were performed to identify common genes between AAV and AS. Based on the co-expressed genes, functional enrichment analysis, protein-protein interaction (PPI) network analysis, and identification of hub genes (HGs) were conducted. Subsequently, co-expression analysis of HGs was performed, and their expression and diagnostic value were validated. We further explored immune cell infiltration and analyzed the correlation between HGs and infiltrating immune cells. Finally, the reliability of the selected pathways was verified.

RESULTS

The results of the common gene analysis suggest that immune and inflammatory responses may be common features in the pathophysiology of AAV and AS. Through the interaction of different analysis results, we confirmed five HGs (CYBB, FCER1G, TYROBP, IL10RA, CSF1R). The CytoHubba plugin and HG validation demonstrated the reliability of the selected five HGs. Co-expression network analysis revealed that these five HGs could influence monocyte migration. Analysis of immune cell infiltration showed that monocytes in ANCA and M0 macrophages in AS constituted a higher proportion of all infiltrating immune cells, with significant differences in infiltration. We also found significant positive correlations between CYBB, FCER1G, TYROBP, IL10RA, CSF1R, and monocytes/M0 macrophages in AAV, as well as between CYBB, FCER1G, TYROBP, IL10RA, CSF1R, and M0 macrophages in AS.

CONCLUSION

These five HGs can promote monocyte differentiation into macrophages, leading to the concurrent occurrence of AAV and AS. Our study provides insights into the mechanisms underlying the coexistence of AAV and AS.

Associations of sleep with cardiometabolic risk factors and cardiovascular diseases: An umbrella review of observational and mendelian randomization studies

Two researchers independently assessed studies published up to February 5, 2023, across PubMed, Web of Science, Embase, and Cochrane Library, to investigate the associations of sleep traits with cardiometabolic risk factors, as well as with cardiovascular diseases. Fourteen systematic reviews consisting of 23 meta-analyses, and 11 Mendelian randomization (MR) studies were included in this study. Short sleep duration was associated with a higher risk of obesity, type 2 diabetes (T2D), hypertension, stroke, and coronary heart disease (CHD) in observational studies, while a causal role was only demonstrated in obesity, hypertension, and CHD by MR. Similarly, long sleep duration showed connections with a higher risk of obesity, T2D, hypertension, stroke, and CHD in observational studies, none was supported by MR analysis. Both observational and MR studies indicated heightened risks of hypertension, stroke, and CHD in relation to insomnia. Napping was linked to elevated risks of T2D and CHD in observational studies, with MR analysis confirming a causal role in T2D. Additionally, snoring was correlated with increased risks of stroke and CHD in both observational and MR studies. This work consolidates existing evidence on a causal relationship between sleep characteristics and cardiometabolic risk factors, as well as cardiovascular diseases.

Sleep Characteristics and Risk of Stroke and Dementia: An Observational and Mendelian Randomization Study

BACKGROUND AND OBJECTIVES

Sleep disturbances are implicated as risk factors of both stroke and dementia. However, whether these associations are causal and whether treatment of sleep disorders could reduce stroke and dementia risk remain uncertain. We aimed to evaluate associations and ascertain causal relationships between sleep characteristics and stroke/dementia risk and MRI markers of small vessel disease (SVD).

METHODS

We used data sets from a multicenter population-based study and summary statistics from genome-wide association studies (GWASs) of sleep characteristics and outcomes. We analyzed 502,383 UK Biobank participants with self-reported sleep measurements, including sleep duration, insomnia, chronotype, napping, daytime dozing, and snoring. In observational analyses, the primary outcomes were incident stroke, dementia, and their subtypes, alongside SVD markers. Hazard ratios (HRs) and odds ratios (ORs) were adjusted for age, sex, and ethnicity, and additional vascular risk factors. In Mendelian randomization (MR) analyses, ORs or risk ratios are reported for the association of each genetic score with clinical or MRI end points.

RESULTS

Among 502,383 participants (mean [SD] age, 56.5 [8.1] years; 54.4% female), there were 7,668 cases of all-cause dementia and 10,334 strokes. In longitudinal analyses, after controlling for cardiovascular risk factors, participants with insomnia, daytime napping, and dozing were associated with increased risk of any stroke (HR 1.05, 95% CI 1.01-1.11, p = 8.53 × 10-3; HR 1.09, 95% CI 1.05-1.14, p = 3.20 × 10-5; HR 1.19, 95% CI 1.08-1.32, p = 4.89 × 10-4, respectively). Almost all sleep measures were associated with dementia risk (all p < 0.001, except insomnia). Cross-sectional analyses identified associations between napping, snoring, and MRI markers of SVD (all p < 0.001). MR analyses supported a causal link between genetically predicted insomnia and increased stroke risk (OR 1.31, 95% CI 1.13-1.51, p = 0.00072), but not with dementia or SVD markers.

DISCUSSION

We found that multiple sleep measures predicted future risk of stroke and dementia, but these associations were attenuated after controlling for cardiovascular risk factors and were absent in MR analyses for Alzheimer disease. This suggests possible confounding or reverse causation, implying caution before proposing sleep disorder modifications for dementia treatment.

Association of daytime napping and nighttime sleep with all-cause mortality: A prospective cohort study of China Health and Retirement Longitudinal Study

STUDY OBJECTIVES

The correlation of daytime napping and nighttime sleep duration on mortality was inconsistent. We aimed to explore their separate links to all-cause/premature mortality, and evaluate their combined impact on all-cause mortality risk.

METHODS

All of 20617 (mean age: 56.90 ± 10.19, 52.18 % females) participants from China Health and Retirement Longitudinal Study were followed for a median of 7 years (interquartile range: 4-7) to detect death status. Baseline self-reported napping and sleep duration was categorized: napping as none, <60 min, 60-90 min, and ≥90 min, sleep as <6 h/night, 6-8 h/night, and ≥8 h/night. Death event was tracked, and premature death was defined using 2015 China's average life expectancy (73.64 years for men, and 79.43 years for women). Cox regression models analyzed the data.

RESULTS

During follow-up, 1621 participants (7.86 %) died, including 985 (4.78 %) premature deaths. Compared to none nappers, napping ≥90 min associated with a higher risk of all-cause mortality (Hazard ratio, [HR] 1.23, 95 % confidence interval [CI] 1.06-1.42) and premature mortality (HR 1.23, 95 % CI 1.02-1.49), while napping <60 min correlated with a lower risk of premature mortality (HR 0.71, 95 % CI 0.54-0.95), after adjustment. Compared to sleep 6-8 h/night, nighttime sleep ≥8 h was associated with an increased risk of all-cause mortality (HR 1.20, 95 % CI 1.04-1.37) and premature mortality (HR 1.28, 95 % CI 1.08-1.52). Participants napping ≥90 min and sleeping ≥8 h had a multi-adjusted HR (95%CI) of 1.50 (95 % CI 1.17-1.92) for all-cause mortality, versus no napping and 6-8 h/night sleep.

CONCLUSIONS

Prolonged napping and extended nighttime sleep linked to increased mortality risk, particularly in combination. Optimizing sleep patterns may have potential implication in mortality prevention.

Sleep and cardiovascular disease

This review centres around the recent evidence in examining the intersection of sleep and cardiovascular disease (CVD). Sleep in this review will be further subdivided to consider both sleep quantity and quality along and will also consider some of the more common sleep disorders, such as insomnia and obstructive sleep apnoea, in the context of CVD. Sleep disorders have been further explored in several specific populations which are both at risk of sleep disorders and CVD. Secondly, the review will present some of the risk factors for CVD that are affected by sleep and sleep disorders which include hypertension, diabetes, and obesity. It will also examine the potential underlying mechanisms including inflammation, appetite control, endocrine, and genetic processes that are affected by sleep and sleep disorders leading to increased risk of CVD development. In addition, we will consider the observed bi-directional relationships between sleep and cardiovascular risk factors. For example, obesity, a risk factor for CVD can be affected by sleep, but in turn can increase the risk of certain sleep disorder development which disrupts sleep, leading to further risk of obesity development and increased CVD risk. Finally, the review will explore emerging evidence around lifestyle interventions that have included a sleep component and how it impacts the management of CVD risk factor. The need for increased awareness of the health effects of poor sleep and sleep disorders will be discussed alongside the need for policy intervention to improve sleep to facilitate better health and well-being.