Joint effect of less than 1 h of daytime napping and seven to 8 h of night sleep on the risk of stroke

Association of habitual sleep duration and its trajectory with the risk of cancer according to sex and body mass index in a population-based cohort

BACKGROUND

The relationship between sleep duration and cancer in China remains inconclusive. The authors investigated the association between sleep duration and cancer from both static and dynamic perspectives.

METHODS

This study was based on the China Health and Retirement Longitudinal Study. We first tested the hazard ratios (HRs) with 95% confidence intervals (CIs) between baseline sleep duration and incident cancer using Cox proportional hazards regression analysis. Sleep duration trajectories from 2011 to 2015 were identified using group-based trajectory modeling to examine the subsequent risk of incident cancer from 2015 to 2018 using Cox proportional hazards regression model.

RESULTS

The risk of incident cancer increased by 69% (HR, 1.69; 95% CI, 1.19-2.39) in individuals who slept for <7 h per day (vs. 7 to ≤8 h), 41% (HR, 1.41; 95% CI, 1.01-1.95) in those who slept for <6 h per night (vs. 6 to ≤8 h), and 60% (HR, 1.60; 95% CI, 1.01-2.55) in those who did not take any naps during the day (vs. >60 min). Stratified by sex and body mass index, the risk of cancer was evident among women with night sleep of <6 h (vs. 6-8 h). However, the duration of <7 h of total sleep among men and overweight individuals was associated with cancer risk. Moreover, individuals with a short night sleep duration but no napping had a higher risk of cancer. Furthermore, cancer risk was only observed in individuals with short stable trajectory of night sleep (HR, 2.01; 95% CI, 1.07-3.80) and among women with short stable trajectory of total sleep (HR, 2.26; 95% CI, 1.13-4.52).

CONCLUSIONS

Cancer incidence risk was observed in participants with sleep duration of <7 h and among women with short stable sleep trajectory. Short nights and total sleep duration were both associated with a high risk of incident cancer, but varied by sex. Interestingly, cancer risk was restricted to women with short stable sleep trajectory.

PLAIN LANGUAGE SUMMARY

This study showed that short nights and total sleep duration were associated with a high risk of cancer incidence in middle-aged and elderly Chinese population, with implications for early effective cancer prevention. Habitual sleep is a modifiable and dynamic lifestyle behavior, and long-term short sleep trajectories among women can predict cancer outcomes. Future studies should examine the association between the trajectory of sleep parameters based on objective measures and specific cancer types.

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.

Relation between sleep disorders and post-stroke cognitive impairment

Objective

To investigate the effects of sleep disorders on post-stroke cognitive impairment (PSCI) and other factors affecting post-stroke cognitive impairment.

Methods

A total of 1,542 first-ever stroke inpatients in department of neurology of Tianjin Huanhu Hospital from 2015.6.1 to 2016.12.31. We recorded the personal history of patients. The MMSE (mini-mental state examination), MoCA (Montreal Cognitive Assessment), HAMD (Hamilton Depression Scale), BI (Barthel index), mRS (Modified Rankin Scale), PSQI (Pittsburgh Sleep Quality Index), ESS (Epworth Sleepiness Scale), Berlin questionnaire, nocturnal TST (total sleep time) were assessed before discharge. All patients were followed up at 3 months, 6 months, and 4 years (2019-2020) after stroke. During follow-up, the above scales should be evaluated again to assess the sleep status and cognitive function of patients at that time.

Results

Nocturnal TST (>8 h) (OR 3.540, 95% CI 1.692-7.406, P = 0.001) was a risk factor for cognitive impairment 3 months after stroke. Nocturnal TST (<7 h) (OR 6.504, 95% CI 3.404-12.427, P < 0.001) was a risk factor for cognitive impairment 6 months after stroke. Low sleep quality (OR 2.079, 95% CI 1.177-3.672, P = 0.012), sleepiness (OR 3.988, 95% CI 1.804-8.818, P = 0.001), nocturnal TST (<7 h) (OR 11.334, 95% CI 6.365-20.183, P < 0.001), nocturnal TST (>8 h) (OR 4.096, 95% CI 1.682-9.975, P = 0.002) were risk factors for cognitive impairment 4 years after stroke. The prevalence of cognitive impairment with TIA were 79.3% at admission, 68.1% at 3-months follow-up, 62.1% at 6-months follow-up and 52.2% at 4-year follow-up.

Conclusion

Long or short nocturnal TST (<7 h or >8 h) was a risk factor for cognitive impairment after stroke (3 months, 6 months and 4 years). Poor sleep quality and sleepiness were shown to be risk factors for cognitive impairment at 4-year follow-up. Cognitive impairment was very common in patients with TIA.

Long Sleep Duration and Stroke-Highly Linked, Poorly Understood

Stroke is one of the leading causes of disability and mortality. Both short and long sleep durations are associated with adverse health outcomes. Cross-sectional studies have shown an increased prevalence of stroke in long sleepers. Long sleep duration increases stroke incidence and mortality in prospective epidemiological studies. Accumulating evidence suggests that the magnitude of the association between sleep and stroke appears to be stronger for longer sleep than shorter sleep, yielding a J-shaped curve. Potential links between long sleep duration and stroke include increased incidence of diabetes and atrial fibrillation, elevated levels of inflammation, arterial stiffness, and blood pressure variability. Long sleep duration is a strong marker and a plausible risk factor for stroke and should be considered in future scoring for risk stratification and stroke prevention.

Association of longitudinal patterns of nighttime sleep duration and daytime napping duration with risk of multimorbidity

OBJECTIVES

To determine whether longitudinal trajectories of nighttime sleep duration and daytime napping duration are related to subsequent multimorbidity risk. To explore whether daytime napping can compensate for negative effects of short nighttime sleep.

METHODS

The current study included 5262 participants from China Health and Retirement Longitudinal Study. Self-reported nighttime sleep duration and daytime napping duration were collected from 2011 to 2015. The 4-year sleep duration trajectories were conducted by group-based trajectory modeling. The 14 medical conditions were defined by self-reported physician diagnoses. Multimorbidity was diagnosed as participants with 2 or more of the 14 chronic diseases after 2015. Associations between sleep trajectories and multimorbidity were assessed by Cox regression models.

RESULTS

During 6.69 years of follow-up, we observed multimorbidity in 785 participants. Three nighttime sleep duration trajectories and three daytime napping duration trajectories were identified. Participants with persistent short nighttime sleep duration trajectory had the higher risk of multimorbidity (hazard ratio = 1.37, 95% confidence interval: 1.06-1.77), compared with those with persistent recommended nighttime sleep duration trajectory. Participants with persistent short nighttime sleep duration and persistent seldom daytime napping duration had the highest risk of multimorbidity (hazard ratio = 1.69, 95% confidence interval: 1.16-2.46).

CONCLUSIONS

In this study, persistent short nighttime sleep duration trajectory was associated with subsequent multimorbidity risk. Daytime napping could compensate for the risk of insufficient night sleep.

Association of Self-Reported Nighttime Sleep Duration with Chronic Kidney Disease: China Health and Retirement Longitudinal Study

INTRODUCTION

The cohort study aimed to assess the association of nighttime sleep duration and the change in nighttime sleep duration with chronic kidney disease (CKD) and whether the association between nighttime sleep duration and CKD differed by daytime napping.

METHODS

This study included 11,677 individuals from the China Health and Retirement Longitudinal Study (CHARLS) and used data from the 2011 baseline survey and four follow-up waves. Nighttime sleep duration was divided into three groups: short (<7 h per night), optimal (7-9 h), and long nighttime sleep duration (>9 h). Daytime napping was divided into two groups: no nap and with a nap. We used Cox proportional hazards model to examine the effect of nighttime sleep duration at baseline and change in nighttime sleep duration on incident CKD and a joint effect of nighttime sleep duration and nap time on onset CKD.

RESULTS

With a follow-up of 7 years, the incidence of CKD among those with short, optimal, and long nighttime sleep duration was 9.89, 6.75, and 9.05 per 1,000 person-years, respectively. Compared to individuals with optimal nighttime sleep duration, short nighttime sleepers had a 44% higher risk of onset CKD (hazard ratio [HR]: 1.44, 95% confidence interval [CI]: 1.21-1.72). Compared to participants with persistent optimal nighttime sleep duration, those with persistent short or long nighttime sleep duration had an increased risk of incident CKD (HR: 1.44, 95% CI: 1.15-1.80). We found a lower incidence of CKD in participants with short nighttime sleep duration and a nap (HR: 0.74, 95% CI: 0.60-0.93), compared to those with short nighttime sleep duration and no nap.

CONCLUSION

Short nighttime sleep duration and persistent long or short nighttime sleep duration were associated with a higher risk of onset CKD. Keeping persistent optimal nighttime sleep duration may help reduce CKD risk later in life. Daytime napping may be protective against CKD incidence.

The independent and combined association of napping and night sleep duration with stroke in Chinese rural adults

BACKGROUND

Inappropriate sleep duration is a potential cause of stroke. But the effect of napping on stroke risk remains controversial and the interaction between night sleep and napping duration remains unclear. The objective of this study was to examine the independent and combined effects of napping and nocturnal sleep duration on stroke.

METHODS

Subjects were derived from a rural cohort study in Henan. The Pittsburgh Sleep Quality Index (PSQI) was applied to identify nap duration and nocturnal sleep duration. Binary logistic regression was employed to indicate the dose-response relationships between naps, nocturnal sleep, total 24-h sleep duration, and stroke.

RESULTS

Among the 37,341 participants (14,485 men), 2600 suffered from a stroke. The odds ratios (ORs) and 95% confidence level (CI) for stroke in the fully adjusted model were 1.37 (1.13-1.65) for men nappers compared to non-nappers. Compared to 7-8 h of sleep per day, night sleep durations < 6 h and ≥ 9 h and 24-h sleep duration ≥ 10 h were linked to increased odds of stroke in men. The ORs (95%CI) were 1.34 (1.06-1.69) in nocturnal sleep duration < 6 h, 1.30 (1.06-1.59) in nocturnal sleep duration ≥ 9 h, and 1.40 (1.15-1.71) in 24-h sleep duration ≥ 10 h in men. In addition, long naps and prolonged nocturnal sleep duration have a joint effect on stroke in the fully adjusted model.

CONCLUSION

The napping duration and nocturnal sleep duration have independently and jointly effects on stroke in rural populations. More research is required to explore the underlying mechanisms for this relationship.

CLINICAL TRIAL REGISTRATION

The Henan Rural Cohort Study has been registered on the Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699) ( http://www.chictr.org.cn/showproj.aspx?proj=11375 ).

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.

Association of sleep duration and napping with stroke mortality in older Chinese: A 14-year prospective cohort study of the Guangzhou Biobank Cohort study

STUDY OBJECTIVE

Evidence regarding the association of short sleep duration and napping with stroke remains limited and controversial. We examined the association of sleep duration and napping with risk of stroke mortality in an older Chinese cohort.

METHODS

Sleep duration and daytime napping were assessed by face-to-face interview during 2003-2008. Information of causes of death until April 30, 2021 was collected via record linkage with the Death Registry. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

Of 27,254 participants aged average 62.0 (standard deviation = 7.1) years, 818 stroke deaths occurred within 388,798 person-years (mean = 14.3 years) of follow-up. A U-shaped relation between sleep duration and risk of stroke mortality was observed. Participants with short (≤5 h/day) or long sleep duration (≥9 h/day) showed higher risks of total stroke mortality, with adjusted HRs (95% CIs) being 1.27 (1.01-1.59) and 1.37 (1.07-1.75), respectively. However, non-significant association of short or long sleep duration with hemorrhagic or ischemic stroke mortality was found. The associations of short and long sleep duration with total stroke mortality were more pronounced in those with hypertension (P for interaction with hypertension = 0.01), with HRs (95% CIs) being 1.37 (1.04-1.82) and 1.77 (1.33-2.36), respectively. No association between napping and risk of stroke mortality was found.

CONCLUSIONS

Both short and long sleep duration, but not daytime napping, were associated with higher risk of stroke mortality. Public health messages to encourage good sleep hygiene may be important, especially for people with hypertension.

Association of nocturnal sleep duration and midday napping with subjective poor hearing among middle-aged and older adults in China

Background

Hearing loss has occurred as a critical concern for aging and health. However, it remains unknown whether nocturnal sleep and midday napping duration are associated with hearing loss in middle-aged and older adults.

Methods

The study comprised 9,573 adults from China Health and Retirement Longitudinal Study, who have completed the survey for sleep characteristics and subjective functional hearing. We collected self-reported nocturnal sleep duration (<5, 5 to <6, 6 to <7, 7 to <9, ≥9 h/night) and midday napping duration (≤5, 5 to ≤30, and >30 min). The sleep information was classified into different sleep patterns. The primary outcome was self-reported hearing loss events. Multivariate Cox regression models and restricted cubic splines were used to investigate the longitudinal association of sleep characteristics with hearing loss. We applied Cox generalized additive models and bivariate exposure-response surface diagrams to visualize the effects of different sleep patterns on hearing loss.

Results

We confirmed 1,073 cases of hearing loss (55.1% female) during the follow-up. After adjusting for demographic characteristics, lifestyle factors and health condition, nocturnal sleep with < 5 h was positively associated with hearing loss [hazard ratio (HR): 1.45, 95% confidence interval [CI]: 1.20, 1.75]. Individuals with napping for 5 to ≤30 min had a 20% (HR: 0.80, 95%CI: 0.63, 1.00) lower risk of hearing loss compared with those with napping ≤ 5 min. Restrictive cubic splines showed the reverse J-shaped association between nocturnal sleep and hearing loss. Moreover, we found significant joint effects of sleeping < 7 h/night and midday napping ≤ 5 min (HR: 1.27, 95% CI: 1.06, 1.52) on hearing loss. Bivariate exposure-response surface diagrams also reflected the finding that short sleep without napping existed the highest risk of hearing loss. Compared with persistently sleeping moderately (7-9 h/night), those who persistently slept < 7 h/night or shifted from < 7 h/night to moderate or > 9 h/night had higher risks of hearing loss.

Conclusion

Inadequate nocturnal sleep was associated with an elevated risk of poor subjective hearing in middle-aged and older adults, while moderate napping decreased the risk of hearing loss. Keeping sleep stable within recommendation duration may be a useful strategy for preventing poor hearing loss.

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 (&lt;7 h) (OR 4.060, 95%CI 1.494–11.034, p = 0.006), nocturnal TST (&gt;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 (&lt;7 h) (OR 13.042, 95%-CI 2.576–66.027, p = 0.002) and nocturnal TST (&gt;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 (&lt;7 h) (OR 2.668, 95% CI 1.250–5.698, p = 0.011) and nocturnal TST (&gt;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 &lt; 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.

Sleep duration, daytime napping, and risk of incident stroke: Nuances by metabolic syndrome from the China health and retirement longitudinal study

Background and purpose

The relationship between sleep duration and stroke are inconclusive in China, especially in those individuals with metabolic syndrome. We aimed to investigate the association between sleep duration and incident stroke in participants with metabolic syndrome or its specific components in China.

Materials and methods

Data were taken from the 2011 and 2015 waves of China Health and Retirement Longitudinal Study (CHARLS). Habitual sleep duration (≤6, 6∼8 [reference], &gt;8 h), daytime napping (0, 1∼60 [reference], and &gt;60 min) were determined by self-reported questionnaires. Metabolic syndrome was defined by blood assessment and biomarkers combined with self-reported doctors’ diagnosis. Incident stroke was determined by reported stroke from 2011 to 2015 wave. Cross-sectional and longitudinal associations between sleep and (incident) stroke at baseline and 4-year follow-up period were tested among the population with metabolic syndrome and its components.

Results

A U-shaped relationship was observed between sleep duration and stroke in cross-sectional analysis. Sleep ≤ 6 h/night had a greater risk of incident stroke (hazard ratio [HR] 1.65; 95% confidence interval [CI] 1.04–2.61) compared with sleep 6∼8 h/night. And the HR of stroke was 1.62 (95%CI, 1.03–2.53) for sleep &lt; 7 h/day compared to 7∼9 h/day. These associations were more evident in the female and individuals aged 45–65 years. Furthermore, the effect of short sleep duration on incident stroke was different in each component of metabolic syndrome, which was more pronounced in participants with elevated blood pressure. And a significant joint effect of sleeping ≤ 6 h/night and no napping on risk of stroke was observed (HR 1.82, 95%CI 1.06–3.12).

Conclusion

Short sleep duration was an independent risk factor for incident stroke, especially among females, individuals aged 45–65 years, or those with some components of metabolic syndrome, such as hypertension. Napping could buffer the risk of short sleep duration on incident 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.

Associations between sleep duration and cardiovascular diseases: A meta-review and meta-analysis of observational and Mendelian randomization studies

The associations between sleep duration and cardiovascular diseases (CVDs) have been explored in many observational studies. However, the causality of sleep duration and many CVDs, such as coronary artery disease (CAD), heart failure (HF), and stroke, remains unclear. In this study, we conducted a systematic meta-review and meta-analysis of the results of observational and Mendelian randomization (MR) studies to examine how sleep duration impacts the risk of CVDs. We searched articles published in English and before 10 September 2021 in PubMed, Web of Science, and Embase. The articles were screened independently by two reviewers to minimize potential bias. We combined the meta-analyses of observational studies and 11 MR studies and summarized evidence of the effect of sleep duration on the risk of CAD, HF, stroke, and cardiovascular and all-cause mortality. Results showed that (a) evidence is accumulating that short sleep duration is a causal risk factor for CAD and HF; (b) abundant evidence from observational studies supports that long sleep duration is associated with the risk of CAD, stroke, and mortality, and long sleep duration has no causal associations with stroke and CAD in the MR studies; the causation of long sleep duration and other CVDs should be further studied; and (c) emerging evidence indicates that an increase in hours of sleep is associated with a decreased risk of CAD. Finally, we discussed the underlying pathophysiological mechanisms underlying short sleep duration and CVDs and suggested that increasing sleep duration benefits cardiovascular health.

Pooled incidence and case-fatality of acute stroke in Mainland China, Hong Kong, and Macao: A systematic review and meta-analysis

Background

Stroke incidence and case-fatality in Mainland China, Hong Kong, and Macao vary by geographic region and rates often differ across and within regions. This systematic review and meta-analysis (SR) estimated the pooled incidence and short-term case-fatality of acute first ever stroke in mainland China, Hong Kong, and Macao.

Methods

Longitudinal studies published in English or Chinese after 1990 were searched in PubMed/Medline, EMBASE, CINAHL, Web of Science, SinoMed and CQVIP. The incidence was expressed as Poisson means estimated as the number of events divided by time at risk. Random effect models calculated the pooled incidence and pooled case-fatality. Chi-squared trend tests evaluated change in the estimates over time. When possible, age standardised rates were calculated. Percent of variation across studies that was due to heterogeneity rather than chance was tested using the I2 statistic.The effect of covariates on heterogeneity was investigated using meta-regressions. Publication bias was tested using funnel plots and Egger’s tests.

Results

Overall, 72 studies were included. The pooled incidences of total stroke (TS), ischaemic stroke (IS) and haemorrhagic stroke (HS) were 468.9 (95% confidence interval (CI): 163.33–1346.11), 366.79 (95% CI: 129.66–1037.64) and 106.67 (95% CI: 55.96–203.33) per 100,000 person-years, respectively, varied according to the four economic regions (East Coast, Central China, Northeast and Western China) with the lowest rates detected in the East Coast. Increased trends over time in the incidence of TS and IS were observed (p<0.001 in both). One-month and three-to-twelve-month case-fatalities were 0.11 (95% CI: 0.04–0.18) and 0.15 (95% CI: 0.12–0.17), respectively for IS; and 0.36 (95% CI: 0.26–0.45) and 0.25 (95% CI: 0.18–0.32), respectively for HS. One-month case-fatality of IS and HS decreased over time for both (p<0.001). Three-to-twelve-month fatalities following IS increased over time (p<0.001). Publication bias was not found.

Conclusions

Regional differences in stroke incidence were observed with the highest rates detected in less developed regions. Although 1-month fatality following IS is decreasing, the increased trends in 3-12-month fatality may suggest an inappropriate long-term management following index hospital discharge.

Registration

Registration-URL: https://www.crd.york.ac.uk/prospero/; Reference code: CRD42020170724

The Impact of Online Learning System on Students Affected with Stroke Disease

Stroke, also known as a cerebrovascular accident, is a medical emergency that causes temporary or permanent behavioral dysfunction in people. Sleep deprivation affects our brains in a variety of ways. The advantages of sleep much justify the risks of not having enough sleep. Sleep deprivation (SD) includes a variety of factors, including prolonged awake. Neuroimaging investigates SD's impact on attention, working memory, mood, and hippocampal learning. We analyzed how this data enriches our mechanistic understanding of these alterations and the clinical illnesses linked with sleep disruption. We have used Cronbach's alpha to test the reliability of a scale, so we then have 19 individual attributes responding to 174 participants via survey. The evaluated result shows the reliability statistics; the value for Cronbach's alpha is .962, which is very excellent as it reaches 1. So, there is very strong reliability. If the value falls under .6, we look back to the mean and standard deviation table and remove the attribute with low values for mean or standard deviation and try the remaining attributes. Cronbach's alpha tells us which attribute or item to delete to increase the reliability, and we also have analyzed the correlation among the class students while watching the same video lecture. We have collected data for at least ten students watching the same video using a webcam. Once the data is collected, we then have applied some correlation techniques to determine the class students' behavior towards the same video lecture. This way, we can see the overall behavior of the class upon a specific video lecture. The study further reveals that subjective happiness is influenced by its efficiency, entertainment value, and effectiveness. Does the research offer an original emphasis on analyzing how does lack of sleep affect our brains? Sleep loss frameworks are minimal compared to the benefits of sleep.

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.

Association between daytime napping and stroke: A dose-response meta-analysis

Daytime napping is common in many regions around the world and has been an important part of people's daily life. Daytime napping has attracted increasing attention in recent years. Thus, we conducted a meta-analysis to evaluate the relationship between daytime napping and stroke, and help reduce the risk of stroke by improving living habits. The Embase, PubMed, Web of Science and PsycINFO databases were searched for cohort studies published before October 2020 and eight eligible studies with 524,408 participants and 5,875 stroke cases were included in the final analysis. The pooled relative risk (RR) of stroke was 1.47 (95% confidence interval [CI]: 1.24-1.74; p < .001) with significant heterogeneity (I²  = 58%, p for heterogeneity = 0.02). However, the heterogeneity decreased when the study in which adjusting for sleep duration and stratifying the results based on sleep duration was not performed was excluded (RR: 1.38; 95% CI: 1.19-1.60, I²  = 44%, p for heterogeneity = 0.10). In dose-response analysis, the linear trend indicated that for every 10-min increase in daytime napping, the risk of stroke increased by 3%. Further well-designed large studies are needed to explore the effects of daytime napping on stroke and the underlying biological mechanisms.

Associations between sleep duration, midday napping, depression, and falls among postmenopausal women in China: a population-based nationwide study

OBJECTIVE

To explore the independent and joint associations of sleep duration, midday napping, and depression with fall accidents in Chinese postmenopausal women.

METHODS

A total of 2,378 postmenopausal women aged ≥ 45 years from the baseline survey of the China Health and Retirement Longitudinal Study were enrolled in the study. Each participant provided data on falls, sleep duration, midday napping by a self-reporting approach. We employed the Chinese version of the Center for Epidemiologic Studies Depression Scale to assess depression. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated to estimate the associations of predictor variables with falls using multivariate logistic regression.

RESULTS

Of the 2,378 postmenopausal women, 478 (20.10%) reported falls in the preceding 2 years. Compared with sleep duration of 7 to 8 h/night, sleep duration of 5 to 6 h/night (OR, 1.49; 95% CI, 1.03-2.15) and of ≤ 5 h/night (OR, 1.63; 95% CI, 1.18-2.25) were associated with a higher fall prevalence. However, no significant correlation was found between sleep duration of > 8 h/night and falls. Furthermore, participants with depression were more likely to report falls (OR, 1.78; 95% CI, 1.41-2.25) than their depression-free counterparts. The duration of midday napping was not independently associated with falls, but significant joint associations of sleeping ≤ 6 h/night and no napping (OR, 1.72; 95% CI, 1.07-2.76) or napping > 60 minutes (OR, 2.14; 95% CI, 1.18-3.89) with more falls were found. Similarly, a combined status of sleeping ≤ 6 h/night and depression was related to more falls (OR, 2.97; 95% CI, 1.86-4.74).

CONCLUSION

The present study demonstrates that short sleep duration and depression are independently associated with more falls among postmenopausal women in China. Moreover, short sleep duration combined with no or long napping, short sleep duration combined with depression are jointly correlated with more falls. Future longitudinal studies are warranted to confirm these findings.

Is there an association among sleep duration, nap, and stroke? Findings from the China Health and Retirement Longitudinal Study

PURPOSE

The objective of this study was to assess the association among nighttime sleep, daytime napping, total sleep duration (nighttime sleep plus daytime napping), and stroke in an elderly Chinese population.

METHODS

Data were derived from the 2011 China Health and Retirement Longitudinal Study (CHARLS) with 4785 Chinese respondents over 65 years old. Four binary logistic regression models were used to estimate odds ratios and 95% confidence intervals of the association among total sleep duration, nighttime sleep, daytime napping, and stroke, adjusting for confounders.

RESULTS

After controlling for sociodemographic characteristics, lifestyle, health status, and comorbidity, there was no association between abnormal nighttime sleep and stroke (P values > 0.05). Compared to individuals with normal total sleep duration (7-8 h per day), short sleep duration (< 7 h per day) was approximately two times more likely to increase the risk of stroke (AOR = 1.81, 95%CI 1.10-2.97). Individuals who reported vision impairment, disability, hypertension, dyslipidemia, and mental health issues were at higher risk of stroke. In addition, physical activities with different levels were associated with a lower risk of stroke. Taking naps was not associated with stroke incidence (AOR = 1.12, 95%CI 0.77-1.64).

CONCLUSION

In this elderly Chinese population, short total sleep duration per 24 h, not merely daytime napping or nighttime sleep, was significantly associated with an increased risk of stroke. Preventive measures for stroke may require a focus on elderly, sedentary individuals who report other health problems.

Association of daytime napping with incident stroke in middle-aged and older adults: a large community-based study

BACKGROUND AND PURPOSE

There are conflicting reports on the association between daytime napping and incident stroke. This study was designed to investigate the relationship between daytime napping and stroke within a community-based cohort.

METHODS

The present prospective study was based on the Sleep Heart Health Study. Napping habits were assessed with a self-reported Sleep Habits Questionnaire. Participants with napping habits of different durations and frequencies were followed up until the first stroke occurred or the final censoring date. Cox proportional hazards models were used to estimate the relationship between napping habits and stroke.

RESULTS

A total of 4757 participants (2219 men, mean age 63.6 ± 11.1 years) were enrolled in this study. Compared with those taking no naps, multivariate proportional hazards models analysis indicated that individuals taking naps with a duration of >60 min [hazard ratio (HR), 2.460; 95% confidence interval (CI), 1.538-3.934] had a higher risk of stroke. There was also an increased risk of stroke among participants taking naps daily (HR, 1.563; 95% CI, 1.059-2.307) or five to six times/week (HR, 1.548; 95% CI, 1.026-2.335). After combining napping durations and frequencies, regular long naps (HR, 1.903; 95% CI, 1.182-3.065) and regular short naps (HR, 1.451; 95% CI, 1.010-2.084) were independent risk factors for incident stroke.

CONCLUSION

Daytime napping with a long duration (>30 min) or a high frequency (≥5 times/week) may increase the risk of stroke.

Daytime napping and successful aging among older adults in China: a cross-sectional study

BACKGROUND

The study aimed to examine the association between daytime napping and successful aging (including its five dimensions, "low probability of disease," "no disease-related disability," "high cognitive functioning," "high physical functioning," and "active engagement with life") among China's older adults using data from the Chinese Health and Retirement Longitudinal Study conducted in 2015.

METHODS

Cross-sectional data were used in the analysis. Multivariable logistic regressions were conducted to investigate the association between daytime napping and successful aging, and stratified analyses were performed to explore differences in nighttime sleep duration.

RESULTS

A total of 7469 participants were included in the analysis. Daytime napping was prevalent in China's older adults (59.3%). The proportion of study participants with "successful aging" was 13.7%. Additionally, 48.6, 91.7, 54.1, 78.5, and 49.1% participants achieved "low probability of disease," "no disease-related disability," "high cognitive functioning," "high physical functioning," and "active engagement with life," respectively. Compared with the 0 min/day napping group, the > 60 min/day napping group was associated with a lower probability of achieving successful aging (OR, 0.762; 95% CI, 0.583-0.996). In the nighttime sleep duration stratification, the findings showed that in the ≥8 h/night group, napping > 60 min per day was associated with a lower likelihood of aging successfully (OR, 0.617; 95% CI, 0.387-0.984). Considering the five dimensions of successful aging, moderate and long daytime napping were negatively associated with "low probability of disease"; long daytime napping had negative associations with "no disease-related disability" and "high physical functioning"; moderate daytime napping had positive associations with "high cognitive functioning" and "active engagement with life."

CONCLUSIONS

Long daytime napping showed a lower likelihood of successful aging among the elderly in China. Special attention is necessary for elderly people who sleep for longer duration both during day and night. Biological and social factors affecting the relationship between daytime napping and successful aging need to be explored in depth in the future.

Sleep duration, midday napping, and sleep quality and incident stroke

Objective

To investigate the associations of sleep duration, midday napping, sleep quality, and change in sleep duration with risk of incident stroke and stroke subtypes.

Methods

Among 31,750 participants aged 61.7 years on average at baseline from the Dongfeng-Tongji cohort, we used Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident stroke.

Results

Compared with sleeping 7 to <8 hours/night, those reporting longer sleep duration (≥9 hours/night) had a greater risk of total stroke (hazard ratio [HR] 1.23; 95% confidence interval [CI] 1.07–1.41), while shorter sleep (<6 hours/night) had no significant effect on stroke risk. The HR (95% CI) of total stroke was 1.25 (1.03–1.53) for midday napping >90 minutes vs 1–30 minutes. The results were similar for ischemic stroke. Compared with good sleep quality, those with poor sleep quality showed a 29%, 28%, and 56% higher risk of total, ischemic, and hemorrhagic stroke, respectively. Moreover, we observed significant joint effects of sleeping ≥9 hours/night and midday napping >90 minutes (HR 1.85; 95% CI 1.28–2.66), and sleeping ≥9 hours/night and poor sleep quality (HR 1.82; 95% CI 1.33–2.48) on risk of total stroke. Furthermore, compared with persistently sleeping 7–9 hours/night, those who persistently slept ≥9 hours/night or switched from 7 to 9 hours to ≥9 hours/night had a higher risk of total stroke.

Conclusions

Long sleep duration, long midday napping, and poor sleep quality were independently and jointly associated with higher risks of incident stroke. Persistently long sleep duration or switch from average to long sleep duration increased the risk of stroke.