Midday Napping, Nighttime Sleep, and Mortality: Prospective Cohort Evidence in China.

Objective: In developed countries, midday napping and nighttime sleep duration have been linked to long-term survival; however, little is known about such effects in less developed regions. Therefore, this study aimed to assess the associations of midday napping and nocturnal sleep with mortality in middle-aged and older Chinese adults. Methods: A nationwide cohort of 15,524 adults aged ≥ 45 years was enrolled from 28 provincial regions across mainland China and followed up from 2011 to 2018, using data from the Chinese Health and Retirement Longitudinal Study. Midday napping and nighttime sleep duration were assessed using standardized questionnaires. Cox proportional hazards models with random intercepts for the surveyed provinces were used to estimate hazard ratios ( HRs) of all-cause mortality, adjusting for sociodemographic characteristics, behavioral factors, and health status. Results: A total of 1,745 deaths occurred during a median follow-up of 7.1 years, and the mean (standard deviation) age was 59 (10.1) years at baseline. Compared with non-nappers, over 60 min nappers had a higher risk of all-cause mortality [ HR: 1.35, 95% confidence interval ( CI): 1.17-1.56], while no significant associations were observed among < 30 min nappers. Compared with sleep duration of 6-8 h/night, both short (< 6 h) and long (≥ 8 h) sleep duration were significantly associated with increased mortality, with corresponding HR (95% CI) estimates of 1.21 (1.05-1.38) and 1.26 (1.10-1.44), respectively. We observed significant patterns for greater risks associated with longer nap duration, with a P trend value < 0.001 for all-cause mortality. No significant evidence of an additive interaction was identified between midday napping and nighttime sleep. Conclusion: Long midday napping and inappropriate nighttime sleep were independently associated with an increased risk of all-cause mortality in middle-aged and older Chinese populations. Biological studies are needed to validate our findings and clarify the mechanisms underlying this association.

Global Burden of Cardiovascular Disease Attributable to High Temperature in 204 Countries and Territories from 1990 to 2019.

Objective: This study aimed to estimate spatiotemporal variations of global heat-related cardiovascular disease (CVD) burden from 1990 to 2019. Methods: Data on the burden of heat-related CVD were derived from the Global Burden of Disease Study 2019. Deaths and disability-adjusted life years (DALYs) were used to quantify heat-induced CVD burden. We calculated the age-standardized mortality rate (ASMR) and DALY rate (ASDR) per 100,000 population to compare this burden across regions. Generalized linear models were applied to evaluate estimated annual percentage changes (EAPC) for temporal trends from 1990 to 2019. The correlation between the socio-demographic index (SDI) and age-standardized rate was measured using the Spearman rank test. Results: Heat-induced CVD caused approximately 90 thousand deaths worldwide in 2019. Global ASMR and ASDR of heat-related CVD in 2019 were 1.17 [95% confidence interval ( CI): 0.13-1.98] and 25.59 (95% CI: 2.07-44.17) per 100,000 population, respectively. The burden was significantly increased in middle and low-SDI regions and slightly decreased in high-SDI regions from 1990 to 2019. ASMR showed an upward trend, with the most considerable increase in low-latitude countries. We observed a negative correlation between SDI and EAPC in ASMR ( r s = -0.57, P < 0.01) and ASDR ( r s = -0.59, P < 0.01) among 204 countries. Conclusion: Heat-attributable CVD burden substantially increased in most developing countries and tropical regions.

Associations of Daytime Napping with Incident Cardiovascular Diseases and Hypertension in Chinese Adults: A Nationwide Cohort Study.

OBJECTIVE: This study aimed to examine the associations of daytime napping with incident risks of cardiovascular diseases (CVDs) and hypertension (HTN). METHODS: Data for napping and CVD outcomes in 25 provinces were collected from baseline (2010) and three waves of follow-up (2012-2017) investigations of the China Family Panel Studies. Cox frailty models with random intercepts for the surveyed provinces were used to assess the longitudinal effects of daytime napping on CVD and HTN. RESULTS: Compared with non-nappers, 30+ min nappers had higher risks of CVD and HTN, while no significant associations were observed among < 30 min nappers. Incident risks among 30- to < 60-min nappers increased by 22% [hazard ratio (HR) 1.22, 95% confidence interval ( CI) 1.08-1.39] for CVD and 21% (1.21, 1.04-1.41) for HTN, respectively, with corresponding HRs of CVD and HTN of 1.27 (1.09-1.47) and 1.38 (1.16-1.65) among ≥ 60 min nappers. Nap-associated CVD risks varied by subgroups, with stronger associations in participants with lower body mass index (< 24 kg/m 2), physically inactive persons, smokers, and participants with longer nighttime sleep (≥ 7 h/night). Significant effects of daytime napping were observed on rural and northern residents only, highlighting great regional variations in CVD risks associated with napping habits. CONCLUSIONS: This cohort study revealed strong evidence that long daytime napping (≥ 30 min) is associated with an increased incidence of cardiovascular events.

Increased Eating Frequency Is Associated with Lower Obesity Risk, But Higher Energy Intake in Adults: A Meta-Analysis.

Body weight is regulated by energy intake which occurs several times a day in humans. In this meta-analysis, we evaluated whether eating frequency (EF) is associated with obesity risk and energy intake in adults without any dietary restriction. Experimental and observational studies published before July 2015 were selected through English-language literature searches in several databases. These studies reported the association between EF and obesity risk (odd ratios, ORs) in adults who were not in dietary restriction. R software was used to perform statistical analyses. Ten cross-sectional studies, consisting of 65,742 participants, were included in this analysis. ORs were considered as effect size for the analysis about the effect of EF on obesity risk. Results showed that the increase of EF was associated with 0.83 time lower odds of obesity (i.e., OR = 0.83, 95% confidence intervals (CI) 0.70-0.99, p = 0.040). Analysis about the effect of EF on differences in participants' energy intake revealed that increased EF was associated with higher energy intake (ß = 125.36, 95% CI 21.76-228.97, p = 0.017). We conclude that increased EF may lead to lower obesity risk but higher energy intake. Clinical trials are warranted to confirm these results and to assess the clinical practice applicability.