Comparative analysis of sleep duration and stroke prevalence in China and the US before and during COVID-19

BackgroundThis study compares sleep duration and stroke risk between residents of China and the U.S. during and outside the COVID-19 pandemic, examining age as an interaction effect.MethodsThis study analyzed data from the National Health and Nutrition Examination Survey (NHANES) and the China Health and Retirement Longitudinal Study (CHARLS). A total of 9131 American adults participated from 2017 to March 2020, and 7678 from August 2021 to August 2023. In China, 13,514 adults participated in 2018 and 9441 in 2020. Stroke incidence was assessed via survey responses, with "yes" indicating a history of stroke. Participants were categorized by age, and multivariable logistic regression and interaction analyses evaluated age effects, supported by subgroup and sensitivity analyses. Restricted cubic splines (RCS) examined nonlinear associations between sleep duration and stroke risk, while mediation analyses investigated the roles of hypertension, diabetes, and lipid abnormalities.ResultsThe study found that during the pandemic, in the multivariable-adjusted model, there was a "U-shaped" association between sleep duration and the prevalence of stroke (China: P for trend = 0.009, P non-linear = 0.0004; the United States: P for trend = 0.012, P non-linear = 0.0004). Similarly, in the multivariable-adjusted model, during the COVID-19 pandemic, compared with the non-pandemic period, long sleep duration (>= 9 h) was potentially a risk factor for the prevalence of stroke among American adults (for those under 60 years old: odds ratio (OR) 95% confidence interval (CI)[1.836(1.138, 2.962)], P = 0.013; for those 60 years old and above: OR 95%CI[1.44(1.15, 1.436)], P = 0.044). In contrast, in China, compared with the pandemic period, the association between long sleep duration (>= 9 h) and the prevalence of stroke was stronger during the non-pandemic period (for those 60 years old and above: OR 95%CI[1.342(1.132, 1.59)], P = 0.001), but no association was found among those under 60 years old. Mediation analysis indicated that in China, lipid abnormalities partially influenced the association between long sleep duration (>= 9 h) and the prevalence of stroke. The mediation proportion was 8.39% in the overall population, and as high as 20.25% among the elderly aged 60 years and above.ConclusionDuring the COVID-19 pandemic, the association between prolonged sleep duration (>= 9 h) and stroke risk among U.S. adults aged under 60 significantly increased, although this trend was less pronounced in China. These findings suggest that public health interventions should account for the varying impact of sleep duration across different populations.