Daytime Napping and the Risk of Cardiovascular Disease and All-Cause Mortality: A Prospective Study and Dose-Response Meta-Analysis

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.

Associations of nighttime sleep, midday napping, and physical activity with all-cause mortality in older adults: the Seniors-ENRICA cohorts

We examined associations between nighttime sleep and midday nap duration with all-cause mortality according to adherence to moderate-to-vigorous physical activity (MVPA) recommendations in older adults. We used data from 3518 and 3273 older adults recruited in the Seniors-ENRICA-1 and 2 cohorts, respectively. Nighttime sleep time was classified as short (< 7 h), middle (≥ 7 and < 8 h), and long (≥ 8 h), and midday napping as no nap, short (≤ 30 min), long (> 30 and ≤ 60 min), and very long (> 60 min). Time spent in MVPA was classified as meeting (i.e., ≥ 150 min/week) or not the MVPA recommendations. All-cause mortality was the main outcome. Analyses were performed with Cox regression and adjusted for the main confounders. Overall, compared with middle nighttime sleep, both short (HR 1.20; 95% CI 1.03-1.39) and long (HR 1.30; 95% CI 1.12-1.52) were associated with higher mortality. Among participants who did not meet MVPA recommendations, the association between short (HR 1.22; 95% CI 1.01-1.48) and long (HR 1.46; 95% CI 1.21-1.77) sleeping duration mortality remained. Short napping was associated with lower mortality (HR 0.83; 95% CI 0.71-0.96) and very long with higher mortality (HR 1.29; 95% CI 1.04-1.59), compared to those who did not nap. Among participants not meeting MVPA recommendations, only very long napping was associated with increased mortality (HR 1.32; 95% CI 1.01-1.73). No associations were identified between nighttime sleep or midday napping with mortality among participants meeting MVPA recommendations. Meeting MVPA recommendations can attenuate the risks associated with short or long sleep duration.

Excessive sleep is associated with worse cognition, cognitive decline, and dementia in mild cognitive impairment

INTRODUCTION

This study examines the link between daytime and nighttime excessive sleep and cognition, cognitive decline, and dementia in individuals with existing mild cognitive impairment (MCI).

METHODS

Using data from the Swedish longitudinal study Good Aging in Skåne, participants aged 60-102 years were retrospectively classified as MCI based on cognitive testing. The average follow-up time was 6.59 years. Mixed linear models assessed cross-sectional and longitudinal associations between excessive sleep patterns (napping ≥2 h or nighttime sleep ≥9 h) and multiple cognitive domains. Cox regressions estimated dementia risk for excessive sleep.

RESULTS

Of 4930 participants, 2052 (41%) had MCI. Excessive daytime napping and nighttime sleep were associated with worse cognition and cognitive decline. Excessive napping and nighttime sleep were also linked to higher dementia risk (hazard ratios: 1.75 and 1.86, respectively).

DISCUSSION

These findings suggest that excessive sleep in MCI is associated with further cognitive decline and dementia.

Highlights

Excessive daytime napping and nighttime sleep are linked cognitive decline for those with MCI.Excessive sleep during the day or at night heighten dementia risk.Worse test scores across multiple cognitive domains were observed for excessive daytime nappers.Excessive sleep in MCI may be a warning sign for further cognitive decline.

To nap or not? Evidence from a meta-analysis of cohort studies of habitual daytime napping and health outcomes

Habitual daytime napping is a common behavioral and lifestyle practice in particular countries and is often considered part of a normal daily routine. However, recent evidence suggests that the health effects of habitual daytime napping are controversial. We systematically searched PubMed, Web of Science, Embase, and Cochrane Library databases from inception to March 9, 2024, to synthesize cohort studies of napping and health outcome risk. A total of 44 cohort studies with 1,864,274 subjects aged 20-86 years (mean age 56.4 years) were included. Overall, habitual napping increased the risk of several adverse health outcomes, including all-cause mortality, cardiovascular disease, metabolic disease, and cancer, and decreased the risk of cognitive impairment and sarcopenia. Individuals with a napping duration of 30 min or longer exhibited a higher risk of all-cause mortality, cardiovascular disease, and metabolic disease, whereas those with napping durations less than 30 min had no significant risks. No significant differences in napping and health risks were observed for napping frequency, percentage of nappers, sample size, sex, age, body mass index, follow-up years, or comorbidity status. These findings indicate that individuals with a long napping duration should consider shortening their daily nap duration to 30 min or less.

Validation of intrinsic capacity and healthy sleep pattern in middle-aged and older adults: a longitudinal Chinese study assessing healthy ageing

OBJECTIVES

Intrinsic capacity (IC), a multidimensional construct encompassing mental and physical capacities, has been established in the aging framework by the World Health Organization. However, the detailed relationship between IC and Chinese sleep patterns (nighttime sleep and post-lunch naps) remains inadequately elucidated.

METHODS

Participants in this study were individuals aged ≥45 years residing in China, included in the China Health and Retirement Longitudinal Study (CHARLS). We analyzed 4 years of CHARLS data from the first wave (May 2011-March 2012) to the second wave (July 2015-January 2016). Data from these waves were utilized for longitudinal analysis. Self-reported data included nighttime sleep and nap duration, along with other baseline characteristics. The IC evaluation involved physical examinations and blood tests. Initially, linear regression was used to assess the relationship between total sleep duration, nighttime sleep duration, nap duration, and IC change between the two waves that were determined by marginal effects (ME) and their corresponding 95% confidence intervals (CIs). Regression splines were employed to explore potential nonlinear associations. Subgroup and sensitivity analyses were conducted to investigate the heterogeneity of IC change under specific conditions and the robustness of our results. Mediation analysis was performed to identify potential factors mediating the relationship between sleep patterns and IC change.

RESULTS

Both excessive (>10 h) (total, ME: -1.12; 95% CI: -1.61, -0.64; nighttime, ME: -1.44; 95% CI: -2.29, -0.59) and insufficient (<6 h) sleep duration (total, ME: -0.43; 95% CI: -0.68, -0.18; nighttime, ME: -0.50; 95% CI: -0.73, -0.27) negatively impacted IC change. Moderate naps (≤60 min) mitigated the decline in IC change (ME: 0.28; 95% CI: 0.07, 0.49). IC values decreased at the slowest rate when nap time constituted one-seventh of total sleep time. The onset of dyslipidemia partially mediated the association between naps (≤60 min) and IC change (P =  0.02).

CONCLUSIONS

These findings suggest that maintaining a healthy sleep pattern of 6-8 h of nighttime or total sleep, along with a post-lunch nap of ≤60 min, helps preserve optimal IC or delay its decline. This is particularly beneficial for cognitive, psychological, and locomotion performance among middle-aged and older adults.

Associations between daytime napping, sleep duration, and depression and 15 cardiovascular diseases: a Mendelian randomization study

Background

Numerous studies have documented the effects of daytime napping, sleep duration, and depression on cardiovascular diseases (CVDs). However, the evidence has been gleaned from observational studies that might be riddled with confounding variables and the possibility of reverse causation bias. Therefore, the present study employed a Mendelian randomization (MR) methodology to meticulously explore the relationships between daytime napping, sleep duration, and depression, and the risk profiles of CVDs.

Methods

Genome-wide significant genetic variants associated with daytime napping, sleep duration, and depression were used as the instrumental variables (IVs). Data on the genetic correlations between these IVs and 15 CVDs were derived from the United Kingdom (UK) Biobank, Finnish Genome Studies, and other large-scale collaborations. We conducted both univariate and multivariate MR analyses to assess the overall effects and mediated relationships after adjusting for potential confounders, including body mass index (BMI), smoking status, and type 2 diabetes. The effect sizes were estimated using inverse variance-weighted (IVW) regression.

Results

The MR analysis revealed that an increased risk of heart failure (HF) [odds ratio (OR): 1.366; 95% confidence interval (CI): 1.013-1.842; P=0.04], coronary atherosclerosis (OR: 1.918; 95% CI: 1.257-2.927; P=0.003), myocardial infarction (MI) (OR: 1.505; 95% CI: 1.025-2.211; P=0.04), and coronary artery disease (CAD) (OR: 1.519; 95% CI: 1.130-2.043; P=0.006) was significantly associated with genetically predicted daytime napping. Prolonged sleep duration was found to be related to a reduced risk of HF (OR: 0.995; 95% CI: 0.993-0.998; P=2.69E-04), peripheral vascular disease (PVD) (OR: 0.984; 95% CI: 0.971-0.997; P=0.02), and CAD (OR: 0.997; 95% CI: 0.994-0.999; P=0.006). Additionally, a statistically significant positive relationship was observed between depressive disorders and the occurrence of atrial fibrillation (AF) (OR: 1.298, 95% CI: 1.065-1.583, P=0.01), indicating a heightened susceptibility. The multivariable MR analyses substantiated the reliability of the observed associations between daytime napping and the incidence of HF and CAD, following adjustments for genetically predicted BMI and smoking. The sensitivity analysis did not reveal any evidence of horizontal pleiotropy or heterogeneity, thus supporting the validity of the study's results.

Conclusions

This MR investigation posits a potential causal nexus between daytime napping, sleep duration, and depression, and the genesis of CVDs, offering new perspectives on the prevention and management of CVDs.

Causal Associations Between Sleep Traits and Low Grip Strength: A Bidirectional Mendelian Randomization Study

Background

Sleep disorders and low grip strength often co-occur clinically and are geriatric symptoms that cause significant socioeconomic burden. Previous observational studies have found an association between sleep behaviors and grip strength, but the causal relationship remains unclear.

Purpose

With the Mendelian randomization (MR) approach, the study aimed to determine the causal association between sleep traits (sleep duration, insomnia, daytime napping, sleep-wake disorders, chronotype) and low grip strength.

Methods

The study used genetic variants from the genome-wide association study (GWAS) archived in UK Biobank and FinnGen. We assessed the potential causal relationship between sleep behaviors and grip strength using inverse variance weighting (IVW), weighted median (WM), and MR-Egger. Additionally, we performed sensitivity analyses using Cochran's Q test, MR Egger Intercept test, funnel plots, and leave-one-out method.

Results

We found that sleep duration is causally negatively associated with low grip strength (OR = 0.618, 95% CI = 0.424-0.900, P = 0.012). Sleep-wake disorders have a positive association with low grip strength (OR = 1.018, 95% CI = 1.002-1.034, P = 0.029). Reversely, high low grip strength risk was causally associated with increased daytime napping (OR = 1.018, 95% CI = 1.004-1.032, P = 0.011).

Conclusion

The study revealed causal associations between sleep duration, sleep-wake disorders, and low grip strength. Understanding their relationship helps in early clinical intervention to improve the life quality of the elderly.

Prevalence and associated factors of napping among older adults in the Philippines

BACKGROUND

The aim of the study is to estimate the prevalence and associated factors of insomnia among older adults in the Philippines.

METHODS

In all, 5206 cross-sectional nationally representative data from older adults (≥ 60 years) of the 2018 Longitudinal Study on Ageing and Health in the Philippines (LSAHP) was analysed. Napping frequency and duration were assessed by self-report.

RESULTS

The prevalence of regular nappers was 35.7%, low or moderate napping (1-59 min) was 10.5% and long napping (≥ 60 min) duration was 25.2%. In the final adjusted model, older age was not significantly associated with low or moderate napping duration but older age was positively associated with long napping duration. High wealth status, physical activity and late insomnia were positively associated with low or moderate napping duration. High wealth status, urban residence, daily activity limitations, and physical activity were positively associated, and currently working status, poor self-rated health status and current alcohol use were negatively associated with long napping duration.

CONCLUSION

One in four older adults reported long napping duration. Sociodemographic, health status and behaviour and sleep parameters were associated with low or moderate and/or long napping duration.

Multidimensional Sleep Profiles via Machine learning and Risk of Dementia and Cardiovascular Disease

Importance

Sleep health comprises several dimensions such as duration and fragmentation of sleep, circadian activity, and daytime behavior. Yet, most research has focused on individual sleep characteristics. Studies are needed to identify sleep profiles incorporating multiple dimensions and to assess how different profiles may be linked to adverse health outcomes.

Objective

To identify actigraphy-based 24-hour sleep/circadian profiles in older men and to investigate whether these profiles are associated with the incidence of dementia and cardiovascular disease (CVD) events over 12 years.

Design

Data came from a prospective sleep study with participants recruited between 20032005 and followed until 2015-2016.

Setting

Multicenter population-based cohort study.

Participants

Among the 3,135 men enrolled, we excluded 331 men with missing or invalid actigraphy data and 137 with significant cognitive impairment at baseline, leading to a sample of 2,667 participants.

Exposures

Leveraging 20 actigraphy-derived sleep and circadian activity rhythm variables, we determined sleep/circadian profiles using an unsupervised machine learning technique based on multiple coalesced generalized hyperbolic mixture modeling.

Main Outcomes and Measures

Incidence of dementia and CVD events.

Results

We identified three distinct sleep/circadian profiles: active healthy sleepers (AHS; n=1,707 (64.0%); characterized by normal sleep duration, higher sleep quality, stronger circadian rhythmicity, and higher activity during wake periods), fragmented poor sleepers (FPS; n=376 (14.1%); lower sleep quality, higher sleep fragmentation, shorter sleep duration, and weaker circadian rhythmicity), and long and frequent nappers (LFN; n=584 (21.9%); longer and more frequent naps, higher sleep quality, normal sleep duration, and more fragmented circadian rhythmicity). Over the 12-year follow-up, compared to AHS, FPS had increased risks of dementia and CVD events (Hazard Ratio (HR)=1.35, 95% confidence interval (CI)=1.02-1.78 and HR=1.32, 95% CI=1.08-1.60, respectively) after multivariable adjustment, whereas LFN showed a marginal association with increased CVD events risk (HR=1.16, 95% CI=0.98-1.37) but not with dementia (HR=1.09, 95%CI=0.86-1.38).

Conclusion and Relevance

We identified three distinct multidimensional profiles of sleep health. Compared to healthy sleepers, older men with overall poor sleep and circadian activity rhythms exhibited worse incident cognitive and cardiovascular health. These results highlight potential targets for sleep interventions and the need for more comprehensive screening of poor sleepers for adverse outcomes.

Naps and cardiovascular disease risk in different age and sex groups: evidence from a large community cohort

STUDY OBJECTIVES

This study examined the relationship between naps and cardiovascular disease (CVD) events or death in different age and sex groups.

METHODS

A total of 3,069 participants stratified by age (< 65, 65-74, and ≥ 75 years old) and sex, underwent Cox regression analysis to assess nap's impact on CVD risk. Restricted cubic spline plots were used for dose-response relationships.

RESULTS

Significant age-stratified interactions were found when exploring the associations between nap frequency or duration and CVD events (Pinteraction = .001, .036, respectively). Individuals younger than 65 years with higher nap frequency or longer nap duration had a significantly increased risk of CVD events (P < .001, P = .001, respectively). The age group of 65-74 years showed significant associations between CVD events and nap frequency or nap duration (P = .017, .016, respectively), together with nap duration and CVD deaths (P = .008). In the subgroup of females aged 65-74, significant associations were found between nap frequency or duration and CVD events (P = .006, .002, respectively). Nap frequency or duration was also significantly associated with CVD deaths (P = .005, .010 respectively).

CONCLUSIONS

This study underscores a noteworthy correlation between a higher frequency or longer duration of daytime nap and an increased susceptibility to CVD among individuals aged 65-74 years, particularly in females. However, further research is needed to better understand the underlying mechanisms.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Sleep Heart Health Study; URL: https://clinicaltrials.gov/ct2/show/study/NCT00005275; Identifier: NCT00005275.

CITATION

Chen C, Guo Q, Cheng Y, Lan Y, Cheng D, Huang J. Naps and cardiovascular disease risk in different age and sex groups: evidence from a large community cohort. J Clin Sleep Med. 2024;20(8):1339-1348.

Association of a Mediterranean Lifestyle With All-Cause and Cause-Specific Mortality: A Prospective Study from the UK Biobank

OBJECTIVE

To examine the association between the Mediterranean lifestyle and all-cause, cancer, and cardiovascular disease (CVD) mortality in a British population.

PATIENTS AND METHODS

We studied 110,799 individuals 40 to 75 years of age from the UK Biobank cohort, free of CVD or cancer between 2009 and 2012 who were followed-up to 2021. The Mediterranean lifestyle was assessed at baseline through the Mediterranean Lifestyle (MEDLIFE) index, derived from the lifestyle questionnaire and diet assessments and comprising three blocks: (1) "Mediterranean food consumption," (2) "Mediterranean dietary habits," and (3) "physical activity, rest, social habits, and conviviality." Death information was retrieved from death register records. Cox regression models were used to analyze the study associations.

RESULTS

During a median 9.4-year follow-up, 4247 total deaths, 2401 cancer deaths, and 731 CVD deaths were identified. Compared with the first quartile of the MEDLIFE index, increasing quartiles had HRs of 0.89 (95% CI, 0.81 to 0.97), 0.81 (95% CI, 0.74 to 0.89), and 0.71 (95% CI, 0.65 to 0.78) (P-trend<.001 for all-cause mortality). For cancer mortality, the quartiles had HRs of 0.90 (95% CI, 0.80 to 1.01), 0.83 (95% CI, 0.74 to 0.93), and 0.72 (95% CI, 0.64 to 0.82) (P-trend<.001). All MEDLIFE index blocks were independently associated with lower risk of all-cause and cancer death, and block 3 was associated with lower CVD mortality.

CONCLUSION

Higher adherence to the Mediterranean lifestyle was associated with lower all-cause and cancer mortality in British middle-aged and older adults in a dose-response manner. Adopting a Mediterranean lifestyle adapted to the local characteristics of non-Mediterranean populations may be possible and part of a healthy lifestyle.

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.

Relationship between daytime napping and cardiovascular disease: A two-sample mendelian randomization study

OBJECTIVE

Daytime napping has been reported to have a potential association with an increased risk of cardiovascular diseases (CVDs) in several cohort studies, but the causal effects are unclear. In this study, we aimed to investigate the relationship between daytime napping and CVDs, as well as to validate causality in this relationship by Mendelian randomization (MR).

METHODS

A two-sample MR method was used to evaluate the causal effect of daytime napping on CVDs. The exposure of daytime napping was extracted from publicly available genome-wide association studies (GWASs) in the UK Biobank, and the outcomes of 14 CVDs were obtained from the FinnGen consortium. A total of 49 single-nucleotide polymorphisms (SNPs) were used as the instrumental variables. The effect estimates were calculated by using the inverse-variance weighted method.

RESULTS

The MR analyses showed that genetically predicted daytime napping was associated with an increased risk of five CVDs, including heart failure (odds ratio (OR): 1.71, 95% CI: 1.19-2.44, p = 0.003), hypertension (OR: 1.51, 95% CI: 1.05-2.16, p = 0.026), atrial fibrillation (OR: 1.71, 95% CI: 1.02-2.88, p = 0.042), cardiac arrythmias (OR: 1.47, 95% CI: 1.47, 95% CI: 1.01-2.13, p = 0.042) and coronary atherosclerosis (OR: 1.77, 95% CI: 1.17-2.68, p = 0.006). No significant influence was observed for other CVDs.

CONCLUSION

This two-sample MR analysis suggested that daytime napping was causally associated with an increased risk of heart failure, hypertension, atrial fibrillation, cardiac arrythmias and coronary atherosclerosis.

Excessive daytime napping independently associated with decreased insulin sensitivity in cross-sectional study - Hyogo Sleep Cardio-Autonomic Atherosclerosis cohort study

Background

Although excessive daytime napping has been shown to be involved in diabetes occurrence, its impact on insulin secretion and sensitivity has not been elucidated. It is speculated that excessive napping disrupts the sleep-wake rhythm and increases sympathetic nerve activity during the day, resulting in decreased insulin sensitivity, which may be a mechanism leading to development of diabetes. We previously conducted a cross-sectional study that showed an association of autonomic dysfunction with decreased insulin sensitivity, though involvement of autonomic function in the association between napping and insulin sensitivity remained unclear. Furthermore, the effects of napping used to supplement to short nighttime sleep on insulin secretion and sensitivity are also unknown. In the present cross-sectional study, we examined the relationships of daytime nap duration and autonomic function with insulin secretion and sensitivity in 436 subjects enrolled in the Hyogo Sleep Cardio-Autonomic Atherosclerosis (HSCAA) Cohort Study who underwent a 75-g oral glucose tolerance test (75-g OGTT), after excluding those already diagnosed with diabetes.

Methods

Daytime nap duration was objectively measured using actigraphy, with the subjects divided into the short (≤1 hour) and long (>1 hour) nap groups. Insulin secretion and sensitivity were determined using 75-g OGTT findings. Standard deviation of normal to normal R-R interval (SDNN), a measure of autonomic function, was also determined based on heart rate variability. Subgroup analysis was performed for the associations of napping with insulin secretion and sensitivity, with the results stratified by nighttime sleep duration of less or greater than six hours.

Results

Subjects in the long nap group exhibited lower insulin sensitivity parameters (QUICKI: β=-0.135, p<0.01; Matsuda index: β=-0.119, p<0.05) independent of other clinical factors. In contrast, no associations with insulin secretion were found in either group. Furthermore, the association of long nap duration with insulin sensitivity was not confounded by SDNN. Specific subgroup analyses revealed more prominent associations of long nap habit with lower insulin sensitivity in subjects with a short nighttime sleep time (β=-0.137, p<0.05).

Conclusion

Long daytime nap duration may be a potential risk factor for decreased insulin sensitivity.

Association between napping and cognitive impairment: A systematic review and meta-analysis

STUDY OBJECTIVES

Increasing evidence suggests that napping is associated with cognitive impairment and dementia, but the conclusions are inconsistent. Moreover, the extent of the risk is uncertain. We therefore conducted a systematic review and meta-analysis to quantify the connection between napping and cognitive impairment.

METHODS

We performed a systematic search of PubMed, EMBASE, Web of Science, and Cochrane Library for studies that were published up to June 2023, and assessed associations between napping and cognitive impairment. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated as the effect sizes for all studies. Heterogeneity and potential publication biases were assessed.

RESULTS

A total of 4535 papers were retrieved, with 20 reports assessing the relationships between napping and cognitive impairment. Pooled analysis indicated that napping was associated with dementia (OR = 1.14; 95% CI: 1.07-1.21). Importantly, we found that those napping longer than 30, 45, and 60 min/day were 35%, 41%, and 40%, respectively, more likely to have an increased risk of cognitive impairment (30 min: OR = 1.35; 95% CI: 1.24-1.48; 45 min: OR = 1.41; 95% CI: 1.27-1.58; 60 min: OR = 1.40; 95% CI: 1.26-1.56). North America and Europe showed that associations existed between napping and cognitive impairment (North America: OR = 1.15; 95% CI: 1.04-1.27; Europe: OR = 1.13; 95% CI: 1.08-1.18).

CONCLUSIONS

This meta-analysis indicated associations between long napping durations and cognitive impairment or dementia, suggesting that longer napping might be a potential risk factor of adverse cognitive outcomes.

Association of Midday Napping with All-Cause Mortality in Chinese Adults: A 8-Year Nationwide Cohort Study

This study aimed to investigate the longitudinal association of estimated daytime nap duration with all-cause mortality in Chinese adults. We conceived a prospective cohort design using adult survey data of the baseline and four follow-up waves (2010-2019) from China Family Panel Studies. Cox frailty models with random intercepts for surveyed provinces were used to estimate risks of all-cause mortality associated with midday napping. Trend and subgroup analyses were also performed stratified by demographic, regional and behavioral factors. Compared with non-nappers, those who reported a long napping duration (≥60 min/day) had an increased risk of all-cause mortality, while shorter napping (<60 min) showed no association with mortality. We observed significant trends for greater risks of mortality associated with longer nap duration. Long nap-associated higher risk of all-cause mortality was seen in a group of nocturnal sleep duration ≥9 h. We identified stronger associations of long nap with mortality among adults aged over 50 years, those with lower BMI (<24 kg/m2), residents in rural regions and unregular exercisers. Long midday napping is independently associated with higher risks of all-cause mortality in Chinese adults.

Association between length of daily siesta and brachial-ankle pulse wave velocity (baPWV): a community-based cross sectional study in North China

INTRODUCTION

To date, many studies have shown a link between siesta and cardiovascular events. Little is known regarding the connection between siesta and brachial-ankle pulse wave velocity (baPWV) levels, even though baPWV can determine the degree of atherosclerosis and vascular stiffness. Thus, we examined the relationship between siesta time and baPWV in a cross-sectional study.

METHODS

Interviews, physical examinations, lab testing, and electron beam computed tomography were all part of the baseline evaluation for participants aged older than 35. Baseline data were compared for 3 different siesta habits: irregular or no siestas, daily short siestas (1 h or less), and daily long siestas (> 1 h). Utilizing logistic regression models and multivariate linear regression, the link between siesta time and baPWV was determined.

RESULTS

Among all 6566 participants, the different siesta groups had a significant difference of the degrees of AS (P < 0.001). The same outcome was true for both males (P < 0.001) and females (P < 0.001). Numerous cardiovascular risk variables and markers of subclinical atherosclerosis were positively correlated with daily extended siestas. Results from the fully adjusted model showed that long siestas (> 60 min, OR = 1.18, 95%CI: 1.06-1.31, P = 0.002) were linked to a more severe level of the baPWV. For age or gender stratification, we found significant differences between non-siesta and > 60 min siesta groups. Multiple linear regression analysis revealed a positive connection between siesta duration and baPWV (β = 0.197, P = 0.038).

CONCLUSIONS

An elevated risk of atherosclerosis was shown to accompany prolonged siestas. These results need to be followed up on with prospective studies and additional lab work.

Self-reported sleep in relation to risk of dementia a quarter of a century later at age 90+: The 90+ Study

OBJECTIVE

To examine sex-specific associations of sleep duration and napping self-reported at mean age of 69 years (range: 53-81) with risk of incident dementia 24 years later at age 90 +.

METHOD

Analytic sample included individuals from a population-based study who reported sleep and napping once in the 1980s and 24 years later (range: 16-38) joined The 90+ Study and were evaluated in-person. Those without dementia at baseline of The 90+ Study were prospectively followed. Hazard ratios [HR] and 95% confidence intervals [CI] of dementia risk were estimated by Cox regression.

RESULTS

Of 574 participants 71% were women, mean age at start of dementia follow-up with The 90+ Study was 93 years (range: 90-102). After 3.3 years (range: 0.4-13.8) of follow-up 47% developed dementia. Higher risk of dementia at age 90+ was seen in women with <6 hours of self-reported sleep per night (adjusted HR = 2.00; 95% CI = 1.15-3.50; p = .01) compared with 8 hours. Lower risk of dementia at 90+ was seen in men with short-to-moderate (<60 minutes) self-reported naps compared with no naps (HR = 0.33; 95% CI = 0.18-0.63; p < .01).

CONCLUSIONS

Sleep and nap 24 years earlier are important risk factors for dementia after age 90.

Daytime napping and coronary heart disease risk in adults: a systematic review and dose-response meta-analysis

PURPOSE

The present study investigated the association between daytime napping and coronary heart disease (CHD) risk among adults.

METHODS

Articles were detected by using PubMed, ISI Web of Science, and Scopus databases until November 8th, 2021. The relevant data were found among the eight included articles and were pooled for meta-analysis in adult participants via a random-effects model.

RESULTS

Among 167,025 adults, the results revealed that daytime napping was associated with an enhanced risk of CHD (risk ratios [RR] = 1.30; 95% CI: 1.06, 1.60; p < 0.001). Subgroup analysis by daytime napping duration also indicated that daytime napping for at least 1 h had three times higher influence on the enhanced risk of CHD (RR = 1.34; 95% CI: 1.14, 1.58; p < 0.001) than that of daytime napping for less than 1 h (RR = 1.10; 95% CI: 1.02, 1.19; p = 0.014). In addition, subgroup analysis by region illustrated that daytime napping was linked with an enhanced risk of CHD in Chinese (RR = 1.41; 95% CI: 1.19, 1.66; p < 0.001), but not in European or American populations. Furthermore, the subgroup analysis of napping duration and risk of CHD suggested that their relation was significant just in those studies that controlled for depressive symptoms (RR = 1.52; 95% CI: 1.29, 1.80; p < 0.001, n = 3) and night sleep duration (RR = 1.42; 95% CI: 1.21, 1.66; p < 0.001, n = 5). The linear dose-response meta-analysis revealed that each 15-min increase in daytime napping was related with a 5% higher risk of CHD (RR = 1.05; 95% CI: 1.02, 1.08; I2 = 58.7%; p < 0.001). Furthermore, nonlinear dose-response meta-analysis revealed a positive linear relationship between daytime napping and CHD risk in adults (p nonlinearity = 0.484, p dose-response = 0.003).

CONCLUSION

Results showed that daytime napping was related with an increased risk of CHD in adults. The evidence from this study suggests that the public should be made conscious of the adverse outcomes of long daytime napping for CHD, notably among the Chinese population. Additional studies are required to confirm potential links between CHD risk and daytime napping.

Daytime napping and risk of liver cancer: A large population-based prospective cohort study

INTRODUCTION AND OBJECTIVES

Liver cancer is a major cause of morbidity and mortality in Japan and worldwide. Daytime napping is a common behavior, especially among older adults, that was related in previous research to unfavorable health conditions. Herein, we investigated the association between daytime napping and liver cancer risk.

MATERIALS AND METHODS

In this prospective cohort study, data from 51,185 participants aged 40-79 years and registered in the Japan Collaborative Cohort Study (JACC Study) were analyzed. Incident cases of liver cancer were diagnosed using cancer registries, hospital records, and death certificates. Daytime napping was assessed using the JACC baseline self-administered questionnaire. We used the Cox regression to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of incident liver cancer among participants in the age categories of the 40s, 50s, 60s, and 70s who reported daytime napping compared with their counterparts who did not.

RESULTS

Within 669,734 person-years of follow-up, 341 participants developed liver cancer. Daytime napping was associated with a higher risk of liver cancer among participants who were in their 60s and 70s of age after adjusting for sex: HRs (95% CIs) 1.88 (1.35-2.61) and 1.96 (1.18-3.26), lifestyle and medical history: 1.76 (1.27-2.47) and 1.82 (1.07-3.09), and history of liver diseases: 1.66 (1.18-2.34) and 1.72 (1.01-2.94), respectively. No associations were detected among participants from the 40s and 50s age groups.

CONCLUSIONS

Daytime napping was associated with a higher risk of liver cancer among older adults.

Sleep duration, daytime napping, and risk of peripheral artery disease: multinational cohort and Mendelian randomization studies

Aims

Sleep duration has been associated with cardiovascular disease, however the effect of sleep on peripheral artery disease (PAD) specifically remains unestablished. We conducted observational and Mendelian randomization (MR) analyses to assess the associations of sleep duration and daytime napping with PAD risk.

Methods and results

Sleep traits were assessed for associations with incident PAD using cohort analysis among 53 416 Swedish adults. Replicated was sought in a case-control study of 28 123 PAD cases and 128 459 controls from the veterans affairs Million Veteran Program (MVP) and a cohort study of 452 028 individuals from the UK Biobank study (UKB). Two-sample Mendelian randomization (MR) was used for casual inference-based analyses of sleep-related traits and PAD (31 307 PAD cases 211 753 controls). Observational analyses demonstrated a U-shaped association between sleep duration and PAD risk. In Swedish adults, incident PAD risk was higher in those with short sleep [<5 h; hazard ratio (HR) 1.74; 95% confidence interval (CI) 1.31-2.31] or long sleep (≥8 h; HR 1.24; 95% CI 1.08-1.43), compared to individuals with a sleep duration of 7 to <8 h/night. This finding was supported by the analyses in MVP and UKB. Observational analysis also revealed positive associations between daytime napping (HR 1.32, 95% CI 1.18-1.49) with PAD. MR analysis supported an inverse association between sleep duration [odds ratio (OR) per hour increase: 0.79, 95% CI, 0.55, 0.89] and PAD and an association between short sleep and increased PAD (OR 1.20, 95% CI, 1.04-1.38).

Conclusion

Short sleep duration was associated with an increased risk of PAD.

Identification of the potential biomarkers associated with circadian rhythms in heart failure

Background

Heart failure (HF) is a syndrome with multiple clinical symptoms resulting from damage to the heart's structure and/or function with various pathogenic factors, which has developed as one of the most severe threats to human health. Approximately 13% of genes and about 8% of proteins contained in the heart are rhythmic, which could lead to HF if disrupted. Herein, we aimed to identify the circadian rhythms-related hub genes as potential biomarkers contributing to the identification and treatment of HF.

Methods

Expression data of ischemic and dilated cardiomyopathy samples with or without HF were collected from the GEO database. First, genes with differential expression in HF and healthy samples were identified, named as differentially expressed genes (DEGs), which were then intersected with circadian rhythms-related genes to identify circadian rhythms-related DEGs. A protein-protein interaction (PPI) network was established to screen hub genes. The performance of the hub genes to identify HF among healthy controls was assessed by referring to the receiver operating characteristic (ROC) curve. Additionally, quantitative real-time polymerase chain reaction (RT-PCR) was run to further validate the hub genes depending on clinical human peripheral blood samples.

Results

A total of 10,163 DEGs were determined, composed of 4,615 up-regulated genes and 5,548 down-regulated genes in HF patients in comparison to healthy controls. By overlapping the circadian rhythms-related genes in the Circadian Gene DataBase (CGDB), 723 circadian rhythms-related DEGs were obtained, mainly enriched in regulating lipid metabolic process, circadian rhythm and AMPK signaling pathway. Eight hub genes were screened out through the PPI network. The ROC curve indicated the high accuracy of five hub genes with AUC > 0.7, which also showed high accuracy validated by the external validation dataset. Furthermore, according to the results of quantitative RT-PCR, the HF group showed significantly increased relative mRNA expression of CRY2 and BHLHE41 while the decreased ARNTL and NPAS2 in comparison to controls, indicating the four hub genes as potential biomarkers of HF.

Conclusion

Our study validated that ARNTL, CRY2, BHLHE41 and NPAS2 could serve as potential biomarkers of circadian rhythm in HF. These results may provide a reference for employing novel markers or targets for the diagnosis and treatment of HF.

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

STUDY OBJECTIVES

Previous observational studies have found conflicting evidence on the relationship between daytime napping and incident cardiovascular diseases (CVDs), but it remains unclear whether these associations present causality. This study aims to verify whether and why there is a causal relationship between these parameters, and whether there is an etiological basis.

METHODS

A two-sample Mendelian randomization analysis was performed using 79 single nucleotide polymorphisms associated with daytime napping. Summary-level data for coronary atherosclerosis, peripheral atherosclerosis, total CVD, and five CVD outcomes were obtained from the FinnGen study. Meta-analyses were aimed at investigating the relationships of excessive daytime napping with total CVD, coronary heart disease, myocardial infarction (MI), and stroke incidence. Subgroup, network meta-analysis (NMA) and trial sequential analysis (TSA) were also performed in this study.

RESULTS

The inverse-variance weighted method demonstrated that a genetic predisposition to more frequent daytime napping was significantly associated with higher odds of coronary atherosclerosis (odds ratio [OR] = 1.55, 95% confidence interval [CI]: 1.11 to 2.17), MI (OR = 1.63, 95% CI: 1.06 to 2.50), and heart failure (OR = 1.80, 95%CI: 1.28 to 2.52). In NMA, an increased risk of developing CVD in people who napped for more than 60 min a day than those who did not nap was demonstrated and then supported by TSA results (summary relative risk = 1.98, 95% CI: 1.39 to 2.82).

CONCLUSION

Habitual daytime napping is causally associated with an increased risk of incident CVD primarily via the development of coronary atherosclerosis. An average napping duration of more than 60 min is associated with an elevated risk of CVD in all participants.

Sleep Duration, Midday Napping, and Serum Homocysteine Levels: A Gene-Environment Interaction Study

The associations of sleep duration and midday napping with homocysteine (Hcy) levels, and whether these sleep behaviors modify the association between genetic predisposition and Hcy levels, has yet to be investigated. We included 19,426 participants without severe health conditions at baseline from the Dongfeng−Tongji cohort. In a subgroup of 15,126 participants with genetic data, a genetic risk score (GRS) based on 18 Hcy-related loci was constructed to test the gene−sleep interactions in Hcy. Hcy levels were higher in subjects with a long sleep duration (≥9 h) and midday napping (>90 min), as compared to those who reported a moderate sleep duration (7 to <8 h) and midday napping (1−30 min) (all p values < 0.05). A long sleep duration and midday napping showed a joint effect in increasing Hcy (p for trend < 0.001). Significant interactions regarding Hcy levels were observed for a long sleep duration with GRS and MTHFR rs1801133, and long midday napping with DPEP1 rs12921383 (all p values for interaction < 0.05). Overall findings indicated that a long sleep duration and midday napping were associated with elevated serum Hcy levels, independently and jointly, and amplified the genetic susceptibility to higher Hcy.

Daytime napping and Alzheimer's dementia: A potential bidirectional relationship

INTRODUCTION

Daytime napping is frequently seen in older adults. The longitudinal relationship between daytime napping and cognitive aging is unknown.

METHODS

Using data from 1401 participants of the Rush Memory and Aging Project, we examined the longitudinal change of daytime napping inferred objectively by actigraphy, and the association with incident Alzheimer's dementia during up to 14-year follow-up.

RESULTS

Older adults tended to nap longer and more frequently with aging, while the progression of Alzheimer's dementia accelerates this change by more than doubling the annual increases in nap duration/frequency. Longer and more frequent daytime naps were associated with higher risk of Alzheimer's dementia. Interestingly, more excessive (longer or more frequent) daytime napping was correlated with worse cognition a year later, and conversely, worse cognition was correlated with more excessive naps a year later.

DISCUSSION

Excessive daytime napping and Alzheimer's dementia may possess a bidirectional relationship or share common pathophysiological mechanisms.

Daytime naps and depression risk: A meta-analysis of observational studies

Background

The relationship between daytime napping and depression remains debatable. Thus, a meta-analysis in this study was conducted to evaluate the relationship between daytime napping and depression.

Methods

The PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases were searched up to February 2022, and the reference lists of the included studies were also retrieved. A random-effects model was used to estimate the combined effect size.

Results

Nine studies with 649,111 participants were included in the final analysis. The pooled odds ratio (OR) was 1.15 (95% confidence interval: 1.01-1.31) with a significant heterogeneity (I ² = 91.3%, P for heterogeneity <0.001), and the results demonstrated an increased risk of depressive symptoms among daytime nappers. Visual inspection of the funnel plot and Egger's and Begg's tests identified no obvious evidence of publication bias.

Conclusion

This meta-analysis indicates that daytime naps are a predictor of depression. The effects of daytime napping on depression may vary depending on the characteristics of people, the pattern of naps, and the individual's sleep experience. The findings may have significant implications for future research on depression.

Relationship between sleep disorders and the prognosis of neurological function after stroke

OBJECTIVE

This study aims to investigate the effects of sleep disorders on the prognosis of neurological function after stroke and other factors affecting the prognosis after stroke.

METHOD

We designed a cohort study. A total of 1,542 patients with their first stroke were hospitalized in the department of neurology of Tianjin Huanhu Hospital from 2015.6.1 to 2016.12.31. We recorded the personal histories of patients. The MMSE (mini-mental state examination), MoCA (Montreal Cognitive Assessment), HAMD (Hamilton Depression Scale), National Institutes of Health Stroke Scale (NIHSS) score, mRS (Modified Rankin Scale), BI (Barthel Index), PSQI (Pittsburgh Sleep Quality Index), ESS (Epworth Sleepiness Scale), Berlin questionnaire, and nocturnal TST (Total sleep time) were assessed before discharge, 3 months, 6 months, and 4 years (2019-2020) after stroke.

RESULT

Low sleep quality (OR 2.019, 95%CI 1.199-3.398, p = 0.008), nocturnal TST (<7 h) (OR 4.060, 95%CI 1.494-11.034, p = 0.006), nocturnal TST (>8 h) (OR 5.928, 95% CI 2.134-16.464, p = 0.001) were risk factors for poor neurological function recovery at 3 months after stroke. Nocturnal TST (<7 h) (OR 13.042, 95%-CI 2.576-66.027, p = 0.002) and nocturnal TST (>8 h) (OR 11.559, 95%-CI 2.108-63.390, p = 0.005) were risk factors for poor neurological function at 6 months after stroke. Nocturnal TST (<7 h) (OR 2.668, 95% CI 1.250-5.698, p = 0.011) and nocturnal TST (>8 h) (OR 2.516, 95% CI 1.080-5.861, p = 0.033) were risk factors for poor neurological function at 4 years after stroke. High risk of OSA (HR 1.582, 95%CI 1.244-2.012, p < 0.001) was a risk factor for all-cause death in patients followed up for 4 years after stroke.

CONCLUSION

Low sleep quality is associated with short-term poor neurological function after stroke. Unusual nocturnal TST (long or short) is associated with short-term or long-term poor neurological function after stroke. A high risk of OSA is associated with a higher risk of all-cause death after stroke.

Daytime napping and cardiovascular risk factors, cardiovascular disease, and mortality: A systematic review

Associations between night sleep duration and cardiovascular risk factors in adults have been well documented. However, the associations for daytime napping remain unclear. In this review, six databases were searched for eligible publications to April 8, 2022. A total of 11 articles were identified for umbrella review on the association of daytime napping with diabetes, metabolic syndrome (MetS), cardiovascular disease (CVD), and mortality in adults, 97 for systematic review on the association with CVD and several CVD risk factors. Our umbrella review showed that the associations of daytime napping with diabetes, MetS, CVD, and mortality in most meta-analyses were mainly supported by weak or suggestive evidence. Our systematic review showed that long daytime napping (≥1 h/d) was associated with higher odds of several CVD risk factors, CVD, and mortality, but no significant association was found between short daytime napping and most of the abovementioned outcomes. Our dose-response meta-analyses showed that daytime napping <30 min/d was not significantly associated with higher odds of most CVD risk factors and CVD among young and middle-aged adults. However, among older adults aged >60 years, we observed significant dose-response associations of daytime napping with higher odds of diabetes, dyslipidemia, MetS, and mortality starting from 0 min/d.

Mediating effects of sleep duration on the association between natural menopause and stroke risk among Chinese women

Background

Sleep disturbance is commonly reported by menopausal women. Stroke risk and poor stroke outcomes in women have usually been attributed to menopause. This study aimed to investigate the mediating effect of sleep duration on relationship between menopause and risk of stroke in natural menopause women.

Materials and methods

A cross-sectional study was performed, and participants were recruited through a multistage, stratified, probability proportional to size sampling method in this research. The stroke risk was measured using the risk assessment form for high-risk stroke population. The average sleep duration was calculated by adding up night sleep and afternoon nap duration. Multivariate regression analysis was conducted to identify the association between menopause, sleep duration, and stroke risk. The direct and indirect effects of menopause on stroke risk were analyzed by using the sleep duration in a mediation framework.

Results

Perimenopause, menopause, average sleep duration, and night sleep duration were significantly associated with stroke risk (P < 0.001), after adjusting for covariates. Perimenopause and menopause were significantly related to average sleep duration (P < 0.001) and night sleep duration (P < 0.001). The average sleep duration (ab = 0.016, 95% CI: 0.003, 0.030; ab = −0.048, 95% CI: −0.070, −0.027) partially mediated the relationship between menopause and stroke risk. And night sleep duration (ab = 0.024, 95% CI: 0.009, 0.040; ab = −0.054, 95% CI: −0.077, −0.033) played a major mediating role, in which night sleep duration of ≤5 h mediated the link between both perimenopause (ab = 0.707, 95% CI: 0.392, 1.021) and menopause (ab = −0.787, 95% CI: −1.096, −0.478) and stroke risk; both night sleep duration of >8–9 h (ab = 0.079, 95% CI: 0.010, 0.193) and >9 h (ab = 0.379, 95% CI: 0.086, 0.712) had mediating effects on perimenopause and stroke risk.

Conclusion

A significant relationship between menopause and stroke risk factors among natural menopausal status was found in this study. The average sleep duration, especially night sleep duration, partially mediated the association between menopause and stroke risk, which is a novel insight to the progression of stroke risk in Women. Suitable prevention methods and interventions for sleep in menopausal women may reduce the risk of stroke.

Association of Sleep Duration, Napping, and Sleep Patterns With Risk of Cardiovascular Diseases: A Nationwide Twin Study

Background

Although sleep disorders have been linked to cardiovascular diseases (CVDs), the association between sleep characteristics and CVDs remains inconclusive. We aimed to examine the association of nighttime sleep duration, daytime napping, and sleep patterns with CVDs and explore whether genetic and early‐life environmental factors account for this association.

Methods and Results

In the Swedish Twin Registry, 12 268 CVD‐free twin individuals (mean age=70.3 years) at baseline were followed up to 18 years to detect incident CVDs. Sleep duration, napping, and sleep patterns (assessed by sleep duration, chronotype, insomnia, snoring, and daytime sleepiness) were self‐reported at baseline. CVDs were ascertained through the Swedish National Patient Registry and the Cause of Death Register. Data were analyzed using a Cox model. In the multiadjusted Cox model, compared with 7 to 9 hours/night, the hazard ratios (HRs) of CVDs were 1.14 (95% CI, 1.01–1.28) for <7 hours/night and 1.10 (95% CI, 1.00–1.21) for ≥10 hours/night, respectively. Compared with no napping, napping 1 to 30 minutes (HR, 1.11 [95% CI, 1.03–1.18]) and >30 minutes (HR, 1.23 [95% CI, 1.14–1.33]) were related to CVDs. Furthermore, a poor sleep pattern was associated with CVDs (HR, 1.22 [95% CI, 1.05–1.41]). The co‐twin matched control analyses showed similar results as the unmatched analyses, and there was no significant interaction between sleep characteristics and zygosity (P values >0.05).

Conclusions

Short or long sleep (<7 or ≥10 hours/night), napping, and poor sleep patterns are associated with an increased CVD risk. Genetic and early‐life environmental factors may not account for the sleep–CVD association.

Associations of sleep and circadian phenotypes with COVID-19 susceptibility and hospitalization: an observational cohort study based on the UK Biobank and a two-sample Mendelian randomization study

Study Objectives

Sleep and circadian phenotypes are associated with several diseases. The present study aimed to investigate whether sleep and circadian phenotypes were causally linked with coronavirus disease 2019 (COVID-19)-related outcomes.

Methods

Habitual sleep duration, insomnia, excessive daytime sleepiness, daytime napping, and chronotype were selected as exposures. Key outcomes included positivity and hospitalization for COVID-19. In the observation cohort study, multivariable risk ratios (RRs) and their 95% confidence intervals (CIs) were calculated. Two-sample Mendelian randomization (MR) analyses were conducted to estimate the causal effects of the significant findings in the observation analyses. Beta values and the corresponding 95% CIs were calculated and compared using the inverse variance weighting, weighted median, and MR-Egger methods.

Results

In the UK Biobank cohort study, both often excessive daytime sleepiness and sometimes daytime napping were associated with hospitalized COVID-19 (excessive daytime sleepiness [often vs. never]: RR=1.24, 95% CI=1.02-1.5; daytime napping [sometimes vs. never]: RR=1.12, 95% CI=1.02-1.22). In addition, sometimes daytime napping was also associated with an increased risk of COVID-19 susceptibility (sometimes vs. never: RR= 1.04, 95% CI=1.01-1.28). In the MR analyses, excessive daytime sleepiness was found to increase the risk of hospitalized COVID-19 (MR IVW method: OR = 4.53, 95% CI = 1.04-19.82), whereas little evidence supported a causal link between daytime napping and COVID-19 outcomes.

Conclusions

Observational and genetic evidence supports a potential causal link between excessive daytime sleepiness and an increased risk of COVID-19 hospitalization, suggesting that interventions targeting excessive daytime sleepiness symptoms might decrease severe COVID-19 rate.

Use of Child Care Attenuates the Link Between Decreased Maternal Sleep and Increased Depressive Symptoms

OBJECTIVE

Sleep disruption is common among postpartum women and is linked with depression. Child care may alleviate parenting stress and protect new mothers against symptoms of depression.

METHODS

Mothers from the NURTURE study, a birth cohort of 666 women of full-term infants, completed questionnaires during home visits when their infants were 3, 6, 9, and 12 months old. The Edinburgh Postnatal Depression Scale and the Perceived Stress Scale were used to measure depressive symptoms and stress, respectively. Mothers reported total nightly sleep duration for themselves and their infants, child care arrangements, marital status, and income. We used mixed-effects models adjusting for income, marital status, and child age to examine the indirect effect of infants' sleep on maternal mental health through mothers' sleep and assessed whether patterns differed depending on child care.

RESULTS

Decreased maternal sleep mediated the association between infant sleep and maternal mental health. When infants slept 1 hour less than usual, mothers slept 7 fewer minutes (B = 0.19, 95% confidence interval [CI], 0.01 to 0.27) and reported more depressive symptoms (B = -0.27, 95% CI, -0.43 to -0.11) and stress (B = -0.33, 95% CI -0.58 to -0.09). Child care moderated the indirect effect; decreased maternal sleep was not associated with increased depressive symptoms (and was not a mediator) when mothers had child care (indirect effect = -0.001, 95% CI, -0.03 to 0.03).

CONCLUSION

Use of infant child care reduced the link between maternal sleep and depressive symptoms. Regular access to child care may be a method to mitigate feelings of depression for new mothers.

Association between sleep duration and incidence of type 2 diabetes in China: the REACTION study

Backgrounds:

Inadequate sleep duration is associated with a higher risk of type 2 diabetes and the relationship is nonlinear. We aim to assess the curve relationship between night sleep duration and the incidence of type 2 diabetes in China.

Methods:

A cohort of 11,539 participants from the REACTION study without diabetes at baseline (2011) were followed until 2014 for the development of type 2 diabetes. The average number of hours of sleep per night was grouped. Incidence rates and odds ratios (ORs) were calculated for the development of diabetes in each sleep duration category.

Results:

Compared to people who sleep for 7 to 8 h/night, people with longer sleep duration (≥9 h/night) had a greater risk of type 2 diabetes (OR: 1.27; 95% CI: 1.01–1.61), while shorter sleep (<6 h/night) had no significant difference in risk of type 2 diabetes. When the dataset was stratified based on selected covariates, the association between type 2 diabetes and long sleep duration became more evident among individuals <65 years of age, male, body mass index <24 kg/m² or with hypertension or hyperlipidemia, no interaction effects were observed. Furthermore, compared to people persistently sleeping 7 to 9 h/night, those who persistently slept ≥9 h/night had a higher risk of type 2 diabetes. The optimal sleep duration was 6.3 to 7.5 h/night.

Conclusions:

Short or long sleep duration was associated with a higher risk of type 2 diabetes. Persistently long sleep duration increased the risk.

Association of Sleep Duration, Midday Napping with Atrial Fibrillation in Patients with Hypertension

Objective

This study aimed to assess the associations of sleep duration, midday napping and the risk of atrial fibrillation (AF) in patients with hypertension.

Methods

We conducted a cross-sectional study enrolling 11,524 hypertensive participates from the Chinese Hypertension Registry Study. Information on sleep duration and midday napping were obtained by a self-administered questionnaire. Multivariate logistic regression analyses were performed to estimate odds ratio (OR) and 95% confidence intervals (CIs) for the risk of AF.

Results

Compared with sleeping 6 to ≤8 hours/night, those reporting shorter sleep duration (≤5 hours/night) had a greater risk of AF (OR 1.95; 95% CI 1.28–2.95) in the fully adjusted model, while longer sleep (≥9 hours/night) was not significantly associated with the risk of AF. Compared with nonhabitual nappers, nappers had a higher risk of AF (OR 1.28; 95% CI 1.03–1.60) in the fully adjusted model. Moreover, we observed significant joint effects of sleeping ≤5 hours/night and nap (OR 2.13; 95% CI 1.09–4.14) on the risk of AF after adjusting for confounding factors.

Conclusion

Short sleep duration and midday napping were independently and jointly associated with higher risks of AF in patients with hypertension.

The effects of napping on night‐time sleep in healthy young adults

The discrepancies in the effects of napping on sleep quality may be due to differences in methodologies, napping behaviours, and daytime activity levels across studies. We determined whether napping behaviours and daytime activity levels are associated with night-time sleep fragmentation and sleep quality in young adults. A total of 62 healthy adults (mean [SD] age 23.5 [4.2] years) completed screening questionnaires for sleep habits, physical activity, medical and psychological history. Actigraphy was used to record sleep including naps. The fragmentation algorithm (K_RA ) was applied to the actigraphic data to measure night-time sleep fragmentation. We classified participants' nap frequency as "non-nappers" (0 naps/8 days), "moderate nappers" (1-2 naps/8 days) or "frequent nappers" (≥3 naps/8 days) naps. Nap duration was defined as "short" (≤60 min) or "long" (>60 min). Naps' proximity to the night sleep episode was defined as "early" (≥7 h) and "late" (<7 h) naps. Outcome variables were night-time K_RA and actigraphic sleep variables. Frequent nappers had a significantly higher K_RA than moderate nappers (p < 0.01) and non-nappers (p < 0.02). Late naps were associated with poorer measures of night sleep quality versus early naps (all p ≤ 0.02). Nap duration and daytime activity were not associated with significant differences in the outcome variables (all p > 0.05). K_RA correlated with sleep duration, sleep efficiency, and awakenings (r = -0.32, -0.32, and 0.53, respectively; all p < 0.05). Frequent napping and late naps may be associated with increased sleep fragmentation and poorer sleep quality, reflected in longer sleep onsets and increased awakenings. These findings have implications for public health sleep hygiene recommendations.

Associations between sleep duration and Mediterranean diet score in Costa Rican adults

Both insufficient and excessive sleep duration have been associated with lower-quality diets in adult populations. However, investigations in Latin America, where different sleep norms may exist (e.g., daily napping), are scarce. Therefore, we examined whether weekday sleep duration and inconsistencies between weekday and weekend sleep duration were related to adherence to the Mediterranean diet among Costa Rican adults. The study population included 2169 controls (74% men) from a population-based case-control study. Usual sleep duration (weekday versus weekend) was self-reported and defined as short, recommended, and long (<7 h, 7-9 h, >9 h, respectively). Inconsistent weekday-weekend sleep duration was defined as >1-h difference. Diet was assessed with a food frequency questionnaire, and adherence to the Mediterranean diet was calculated with the Alternative Mediterranean Diet Score (AMED). Sex-stratified linear regression models were conducted with AMED score as a continuous outcome and sleep variables as categorical or dichotomous exposures (in separate models). Models were adjusted for age, area of residence, education, napping, caffeine intake, smoking status, type 2 diabetes mellitus, hypertension, and physical activity. Average (SD) hours of sleep per night reported were 7.0 (1.4) on weekdays and 7.3 (1.6) on weekends for men, and 7.0 (1.5) on weekdays and 7.2 (1.6) on weekends for women. Among women, sleep duration <7-h per night was associated with a lower AMED score compared to those with recommended sleep duration (β: -0.35, CI: -0.63 to -0.07). Unstratified models showed a suggestive association between inconsistent weekday-weekend sleep and lower AMED scores that did not vary by sex (β: -0.08, CI: -0.16, 0.006; P, interaction with sex = 0.93). Lastly, the napping frequency was not associated with AMED scores in any model. In conclusion, short and inconsistent sleep duration may affect the dietary patterns of Costa Ricans.

Cardiovascular risks and sociodemographic correlates of multidimensional sleep phenotypes in two samples of US adults

Study Objectives

Sleep is a modifiable risk factor for cardiovascular conditions. Holistic examination of within-person, multidimensional sleep patterns may offer more detailed information about the sleep-cardiovascular condition link, including who is more vulnerable to both. This study aimed to identify common sleep phenotypes in adulthood, establish the validity of the phenotypes in relation to cardiovascular conditions, and explore sociodemographic and background characteristics of the phenotypes.

Methods

Across two independent samples of adults (N ₁ = 4600; N ₂ = 2598) from the Midlife in the United States Study, latent class analysis (LCA) extracted sleep phenotypes using five key self-reported sleep dimensions. Log-binomial regression was used to determine whether sleep phenotypes differentially predicted cardiovascular conditions, adjusting for known risk factors. LCA with covariates was used to compare sociodemographic characteristics of the identified sleep phenotypes.

Results

Four sleep phenotypes were identified consistently across the two samples: good sleepers, nappers, dissatisfied/inefficient sleepers, and irregular sleepers. Compared to good sleepers (reference), dissatisfied/inefficient sleepers exhibited a higher risk of cardiovascular conditions in both samples (RR _Sample1: 29%, RR _Sample2: 53%) and consisted of relatively more racial/ethnic minorities. Nappers exhibited a higher risk of cardiovascular conditions in one sample (RR _Sample1: 38%) and consisted of more women and older adults. Irregular sleepers exhibited no significantly different cardiovascular risk and were relatively younger.

Conclusions

Common sleep phenotypes in adulthood exhibit differential risks for cardiovascular conditions. Cooccurring sleep dissatisfaction and inefficiency, in particular, may relate to increased risk of cardiovascular conditions. Certain sociodemographic groups (racial minorities, women, older adults) disproportionately fit within high-risk sleep phenotypes.

Associations Between Total Sleep Duration and Cognitive Function Among Middle-Aged and Older Chinese Adults: Does Midday Napping Have an Effect on It?

Aim

The effect of sleep duration on cognitive function has been reported. However, the studies about the combined effects of total sleep duration and midday napping on cognition in elders were limited and inconclusive. We aimed to investigate the associations between total sleep duration, midday napping and cognitive function among middle-aged and older Chinese adults.

Methods

Based on the 3rd wave of the China Health and Retirement Longitudinal Study (CHARLS) in 2015, a total of 9218 participants aged ≥45 years with completed cognition measurements were included. Cognitive functions were assessed by a combined global cognition score of episodic memory and mental status. Information about sleep-related variables, demographic characteristics, and health status were collected by validated questionnaires. Multivariate linear regression models were performed to evaluate the associations between total sleep duration, midday napping, and cognitive function. Stratified analyses were used to explore the potential effect modifier.

Results

Overall, the global cognition score was 10.38 ± 4.30 among the participants (mean age: 61.5 ± 8.7 years). For sleep duration, both short sleep and long sleep duration were significantly associated with the increased risk of cognitive impairment after controlling for demographics and other confounders. Compared with sleeping for 7h per day, the adjusted β-coefficient and 95% CI of the risk of cognitive impairment was −0.967 (95% CIs: −1.191, −0.742) for ≤5h, −0.257 (−0.498, −0.016) for 6h, −0.424 (−0.650, −0.198) for 8h and −0.664 (−0.876, −0.452) for ≥9h. The combined effect analysis indicated that subjects with extended or without naps had a significantly higher risk of cognitive impairment in the ≤5h sleep time group (ref: 7h) and in extended nappers or without naps group (ref: short nappers). Subjects with extended naps or without naps might increase the risk of cognitive impairment, especially those having ≤5h total sleep time. Stratified analysis showed that participants aged ≥60 years without social activity increased the risk of cognitive decline.

Conclusion

An inverted U-shaped association was observed between total sleep duration and cognitive function in Chinese elders, especially in those aged ≥60 years or without social activity. Short midday naps could mitigate the deleterious effects of poor sleep quality and shorter sleep duration on cognitive function. The findings could help us identify the vulnerable population and decrease the burden of cognitive impairment.

Daytime napping is associated with retinal microcirculation: a large population-based study in China

STUDY OBJECTIVES

To investigate the association between daytime napping and retinal microcirculation.

METHODS

This is a cross-sectional study from a prospective population-based cohort. 2,662 participants were recruited after quota sampling. Information on napping was collected through face-to-face interviews. Retinal vascular calibers (RVCs), including central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE), and arterio-to-venous ratio (AVR), were obtained from fundus photography. Multivariate regression and restricted cubic spline curve were performed to determine the association between RVCs and daytime napping duration.

RESULTS

56.4% participants reported daytime napping regularly. Compared to no nap, daytime nap was related to higher CRAE, with nap duration of 0.5-1 h showing the most significant association. 0.5-1 h daytime nappers displayed an average of 4.18 µm (95% confidence interval [CI] 2.45-5.91, p < 0.001) wider CRAE than non-nappers after adjustment. No significant association was found between CRVE and daytime napping. Moreover, individuals with 0.5-1 h daytime napping had a lower risk for AVR reduction (odds ratio [OR] 0.70, 95% confidence interval [CI] 0.56-0.86, p = 0.001) than non-nappers. Similar association persisted in non-hypertensive population. Restricted cubic spline indicated a J-shaped relationship between AVR reduction and nap duration.

CONCLUSION

Retinal microcirculation was positively associated with self-reported 0.5-1 h daytime napping. Better indicators of retinal microcirculation were probably related to nap duration in a J-shaped manner. Also, the possibly beneficial role of 0.5-1 h daytime napping on retinal microcirculation might be independent of clinically diagnosed vascular diseases.

Role of sleep deprivation in immune-related disease risk and outcomes

Modern societies are experiencing an increasing trend of reduced sleep duration, with nocturnal sleeping time below the recommended ranges for health. Epidemiological and laboratory studies have demonstrated detrimental effects of sleep deprivation on health. Sleep exerts an immune-supportive function, promoting host defense against infection and inflammatory insults. Sleep deprivation has been associated with alterations of innate and adaptive immune parameters, leading to a chronic inflammatory state and an increased risk for infectious/inflammatory pathologies, including cardiometabolic, neoplastic, autoimmune and neurodegenerative diseases. Here, we review recent advancements on the immune responses to sleep deprivation as evidenced by experimental and epidemiological studies, the pathophysiology, and the role for the sleep deprivation-induced immune changes in increasing the risk for chronic diseases. Gaps in knowledge and methodological pitfalls still remain. Further understanding of the causal relationship between sleep deprivation and immune deregulation would help to identify individuals at risk for disease and to prevent adverse health outcomes.

Nighttime sleep duration, daytime napping, and metabolic syndrome: findings from the China Health and Retirement Longitudinal Study

PURPOSE

This study aimed to assess the association between nighttime sleep, daytime napping, and metabolic syndrome (MetS) in an elderly Chinese population.

METHODS

A cross-sectional study was conducted using data from the 2011 China Health and Retirement Longitudinal Study (CHARLS) to examine the association between nighttime sleep, daytime napping, and MetS (defined according to the Chinese Diabetes Society criteria). Sleep duration was assessed by a self-reported questionnaire. Binary logistic regression models were used to estimate odds ratios and 95% confidence intervals of the associations adjusting for covariates.

RESULTS

Among 4785 elderly Chinese aged over 65 years old, there was no association between short-time sleep duration (< 7 h/day) and MetS. However, long-time sleep duration (> 8 h/day) decreased the odds of MetS by 53% (aOR= 0.47; 95% CI 0.23-0.96) compared to normal sleep duration (7-8 h/day). Compared to no daytime napping, short-time napping (≤ 30 min/day) was associated with increased odds of MetS (aOR = 1.55, 95% CI 1.02-2.36) and long-time napping (> 30 min/day) was associated with even higher odds of MetS (aOR = 1.77, 95%CI 1.24-2.53). Individuals who were over 75 years old, with elementary school education, and good health status had lower odds of MetS, while women, individuals living in rural areas, and those who reported poor health status had higher odds of MetS.

CONCLUSION

Long-time sleep duration decreased and daytime napping increased the risk of MetS among the elderly Chinese population. We speculate that increasing nighttime sleep duration and decreasing daytime napping may help reduce the risk of MetS.

Sleep duration and anthropometric indices in an Iranian population: the Fasa PERSIAN cohort study

Recent decades have seen a dramatic rise in the prevalence of obesity. While genetic factors can influence obesity, environmental factors and lifestyle may play important roles as well. Sleep can be regarded as one of these factors. This study aimed to examine sleep duration, as a potential risk factor for obesity in an Iranian population. In this cross-sectional study, the Fasa PERSIAN cohort study data was used and 10,136 subjects aged 35-70 were entered. Anthropometrics indices have been measured and the total body fat percentage (BFP) was obtained by Bio-Impedance Analysis. Also, physical activity and dietary intake have been recorded. Sleep duration was obtained and individuals categorized into two groups of "< 8" and "≥ 8" h of sleep. The mean age and sleep duration of the participants were 48.63 ± 9.57 years and 6.92 ± 1.62 h in the total population, respectively. All of the anthropometric indices were significantly higher in the "< 8 h of sleep" group than in the "≥ 8 h of sleep" group. Regarding BFP and fat mass index (FMI) the same results was seen (p-value < 0.05). Body mass index (BMI), Waist and hip circumferences (WC, HC), and waist-to-height ratio (WHtR) were in a significant negative association with night time sleep (p-value < 0.001), while these associations with daytime napping were positive (p-value < 0.001). After multi-variable adjusting, BMI, WC, HC, WHtR, and wrist circumference showed significant negative associations with 24-h sleep duration (p-value < 0.05). This study established the association between nocturnal, daytime napping, 24-h sleep duration and obesity parameters. Daytime napping was positively associated with obesity parameters and short 24-h sleep duration was associated with higher risk of overweight/obesity. These results indicate that insufficient sleep can be a screening indicator for an unhealthy lifestyle and poor health outcomes.

Influences of Lavender Essential Oil Inhalation on Stress Responses during Short-Duration Sleep Cycles: A Pilot Study

Lavender essential oil (LEO) was reported to improve sleep quality. We investigated the influence of aromatherapy by testing the effects of LEO on stress responses during a short-duration sleep in a single-blind, randomized, crossover trial. The subjects were twelve healthy adults who were nonsmokers without any known disease and who were not prescribed medications, and nine of these completed the study. After the subjects had fallen asleep, they were sprayed with LEO using an aroma diffuser. Before and after 90 min of sleep, α-amylase, chromogranin A (CgA), and cortisol levels in saliva were measured as objective stress indicators, and the Japanese version of the UWIST Mood Adjective Checklist was used as a subjective indicator. A comparison of changes before and after sleep, with and without LEO, revealed that the cortisol level did not significantly change; however, α-amylase (p < 0.05) and CgA (p < 0.01) levels significantly decreased after LEO inhalation. A mood test indicated no change in mood before and after sleep, with or without LEO. Since α-amylase and CgA reflect the sympathetic nervous system response, these results indicate that LEO aromatherapy during a short-duration sleep cycle suppresses the stress response, especially that of the sympathetic nervous system.

Association of Meal and Snack Patterns With Mortality of All-Cause, Cardiovascular Disease, and Cancer: The US National Health and Nutrition Examination Survey, 2003 to 2014

Background

Although accumulating evidence has demonstrated that consumption time of energy and macronutrients plays an important role in maintaining health, the association between consumption time of different foods and cardiovascular disease, cancer, and all‐cause mortalities is still largely unknown.

Methods and Results

A noninstitutionalized household population of the US 21 503 participants from National Health and Nutrition Examination Survey was included. Meal patterns and snack patterns throughout a whole day were measured using 24‐hour dietary recall. Principal component analysis was performed to establish dietary patterns. Cox proportional hazards models were used to evaluate the association between dietary patterns across meals and cardiovascular disease (CVD), cancer, and all‐cause mortalities. During the 149 875 person‐years of follow‐up, 2192 deaths including 676 deaths because of CVD and 476 because of cancer were documented. After adjusting for potential confounders, participants consuming fruit‐lunch had lower mortality risks of all‐cause (hazard ratio [HR], 0.82; 95% CI, 0.72–0.92) and CVD (HR, 0.66; 95% CI, 0.49–0.87); whereas participants who consumed Western‐lunch were more likely to die because of CVD (HR, 1.44; 95% CI, 1.10–1.89). Participants who consumed vegetable‐dinner had lower mortality risks of all‐cause, CVD, and cancer (HR_all‐cause, 0.69; 95% CI, 0.60–0.78; HR_CVD, 0.77; 95% CI, 0.61–0.95; HR_cancer, 0.63; 95% CI, 0.48–0.83). For the snack patterns, participants who consumed fruit‐snack after breakfast had lower mortality risks of all‐cause and cancer (HR_all‐cause, 0.78; 95% CI, 0.66–0.93; HR_cancer, 0.55; 95% CI, 0.39–0.78), and participants who consumed dairy‐snack after dinner had lower risks of all‐cause and CVD mortalities (HR_all‐cause, 0.82; 95% CI, 0.72–0.94; HR_CVD, 0.67; 95% CI, 0.52–0.87). Participants who consumed a starchy‐snack after main meals had greater mortality risks of all‐cause (HR_{after‐breakfast}, 1.50; 95% CI, 1.24–1.82; HR_{after‐lunch}, 1.52; 95% CI, 1.27–1.81; HR_{after‐dinner}, 1.50; 95% CI, 1.25–1.80) and CVD (HR_{after‐breakfast}, 1.55; 95% CI, 1.08–2.24; HR_{after‐lunch}, 1.44; 95% CI, 1.03–2.02; HR_{after‐dinner}, 1.57; 95% CI, 1.10–2.23).

Conclusions

Fruit‐snack after breakfast, fruit‐lunch, vegetable‐dinner, and dairy‐snack after dinner was associated with lower mortality risks of CVD, cancer, and all‐cause; whereas Western‐lunch and starchy‐snack after main meals had greater CVD and all‐cause mortalities.

Objective Assessment of Daytime Napping and Incident Heart Failure in 1140 Community-Dwelling Older Adults: A Prospective, Observational Cohort Study

Background Disrupted nighttime sleep has been associated with heart failure (HF). However, the relationship between daytime napping, an important aspect of sleep behavior commonly seen in older adults, and HF remains unclear. We sought to investigate the association of objectively assessed daytime napping and risk of incident HF during follow-up. Methods and Results We studied 1140 older adults (age, 80.7±7.4 [SD] years; female sex, 867 [76.1%]) in the Rush Memory and Aging Project who had no HF at baseline and were followed annually for up to 14 years. Motor activity (ie, actigraphy) was recorded for ≈10 days at baseline. We assessed daytime napping episodes between 9 am and 7 pm objectively from actigraphy using a previously published algorithm for sleep detection. Cox proportional hazards models examined associations of daily napping duration and frequency with incident HF. Eighty-six participants developed incident HF, and the mean onset time was 5.7 years (SD, 3.4; range, 1-14). Participants who napped longer than 44.4 minutes (ie, the median daily napping duration) showed a 1.73-fold higher risk of developing incident HF than participants who napped <44.4 minutes. Consistently, participants who napped >1.7 times/day (ie, the median daily napping frequency) showed a 2.20-fold increase compared with participants who napped <1.7 times/day. These associations persisted after adjustment for covariates, including nighttime sleep, comorbidities, and cardiovascular disease/risk factors. Conclusions Longer and more frequent objective napping predicted elevated future risk of developing incident HF. Future studies are needed to establish underlying mechanisms.

[Lifestyle changes for stroke prevention]

Changes of lifestyle have a substantial effect on stroke prevention, especially in high-risk patients. Maintaining a healthier lifestyle can have greater effects than most pharmacological therapies of cardiovascular prevention. For example, increasing the amount of physical activity, adopting a healthy diet, limiting alcohol consumption and quitting smoking are associated with a 70 % decrease in stroke risk. Despite the abundance of observational data and meta-analyses assessing the association of different lifestyle changes and stroke risk, the literature frequently lacks evidence from randomized controlled clinical trial. This article will provide an overview of various forms of lifestyle changes and summarize their potential to modify the risk of stroke.

Cardiovascular Complications of Sleep Disorders: A Better Night's Sleep for a Healthier Heart / From Bench to Bedside

Sleep is essential to and an integral part of life and when lacking or disrupted, a multitude of mental and physical pathologies ensue, including cardiovascular (CV) disease, which increases health care costs. Several prospective studies and meta-analyses show that insomnia, short (<7h) or long (>9h) sleep and other sleep disorders are associated with an increased risk of hypertension, metabolic syndrome, myocardial infarction, heart failure, arrhythmias, CV disease risk and/or mortality. The mechanisms by which insomnia and other sleep disorders lead to increased CV risk may encompass inflammatory, immunological, neuro-autonomic, endocrinological, genetic and microbiome perturbations. Guidelines are emerging that recommend a target of >7 h of sleep for all adults >18 years for optimal CV health. Treatment of sleep disorders includes cognitive-behavioral therapy considered the mainstay of non-pharmacologic management of chronic insomnia, and drug treatment with benzodiazepine receptor agonists binding to gamma aminobutyric acid type A (benzodiazepine and non-benzodiazepine agents) and some antidepressants. However, observational studies and meta-analyses indicate an increased mortality risk of anxiolytics and hypnotics, although bias may be involved due to confounding and high heterogeneity in these studies. Nevertheless, it seems that the risk incurred by the non-benzodiazepine hypnotic agents (Z drugs) may be relatively less than the risk of anxiolytics, with evidence indicating that at least one of these agents, zolpidem, may even confer a lower risk of mortality in adjusted models. All these issues are herein reviewed.

Effects of nighttime sleep duration and sex on the association between siesta and hypertension

OBJECTIVE

To examine the association between siesta and hypertension by sex and nighttime sleep duration among Chinese adults aged ≥35 years in Yinzhou, Ningbo City.

METHODS

All data were obtained from physical examinations and structured questionnaires. A total of 44, 652 participants were included. Logistic regression models were applied to calculate odds ratios and 95% confidence intervals for the association between siesta and hypertension.

RESULTS

When compared with no siesta, siesta durations of 60∼89 min (OR = 1.10, 95% CI:1.04-1.17) and ≥90 min (OR = 1.21, 95% CI:1.08-1.36) were associated with higher risk of hypertension in women. But no significant association was observed in men. Siesta durations of 30∼59 min (OR = 1.09, 95% CI:1.00-1.19) and 60-89 min (OR = 1.10, 95% CI:1.05-1.16) were associated with hypertension in people with 6∼8 h sleep, and this association appeared seemingly stronger with ≥90 min siesta either in short (<6 h) sleepers (OR = 1.20, 95% CI: 0.99-1.47) or in long (>8 h) sleepers (OR = 1.29, 95% CI: 1.00-1.68). However, in short sleepers, 60∼89 min siesta seemed to be associated with decreased risk of hypertension (OR = 0.95, 95% CI: 0.85-1.06); while in long sleepers, the same range of siesta seemed to be associated with increased risk of hypertension (OR = 1.11, 95% CI: 0.93-1.34).

CONCLUSION

Long siesta was associated with increased risk of hypertension in women but not in men. Not too long siesta may be related to decreased risk of hypertension in short sleepers but not in people with adequate or even long sleep. These findings warrant further examination with prospective studies and laboratory investigations.

Cross-sectional and longitudinal associations between sleep duration, sleep quality, and bone stiffness in European children and adolescents

In this large perspective cohort among European children and adolescents, we observed that daytime napping was positively associated with bone stiffness, while short or long sleep duration combined with poor sleep quality was associated with less bone stiffness. Our findings are important for obtaining optimal bone stiffness in childhood.

INTRODUCTION

To examine the cross-sectional and longitudinal associations between sleep duration, sleep quality, and bone stiffness index (SI) in European children and adolescents.

METHODS

Four thousand eight hundred seventy-one children aged 2-11 years from the IDEFICS study and 861 children aged 6-15 years from the subsequent I.Family study were included. Sleep duration (i.e., nocturnal sleep and daytime napping) and sleep quality (i.e., irregularly bedtime routine, have difficulty falling asleep and trouble getting up in the morning) were reported by self-administrated questionnaires. Nocturnal sleep duration was converted into age-specific z-scores, and total sleep duration was classified into short, adequate, and long based on the National Sleep Recommendation. Calcaneal SI of both feet were measured using quantitative ultrasound. Linear mixed-effects models with country as a random effect were used, with adjustments for sex, age, pubertal status, family socioeconomic status, physical activity, screen time, body mass index, and daylight duration.

RESULTS

Nocturnal sleep duration z-scores were positively associated with SI percentiles among participants with adequate sleep duration at baseline. Moreover, the positive association between daytime napping and SI percentiles was more pronounced in participants with adequate sleep duration at baseline, while at 4-year follow-up was more pronounced in participants with short sleep duration. In addition, extreme sleep duration at baseline predicted lower SI percentiles after 4 years in participants with poor sleep quality.

CONCLUSION

The positive associations between nocturnal sleep, daytime napping and SI depended on total sleep duration. Long-term detrimental effect of extreme sleep duration on SI only existed in individuals with poor sleep quality.