U-shaped associations between sleep duration and Framingham risk score in Korean adults

Background: Sleep problems and cardiovascular disease (CVD) are major public health concerns in Korea. Despite Korea’s chronically short sleep duration and increasing CVD burden, recent population-based evidence examining the association between sleep duration and cardiovascular risk in Korean adults remains limited, particularly studies accounting for complex sample weighting and population representativeness. This study aimed to examine the association between sleep duration and cardiovascular risk among Korean adults.

Methods: A cross-sectional study was conducted using data from the 2020–2022 Korea National Health and Nutrition Examination Survey (KNHANES). The study included adults aged ≥30 years without a history of CVD (n=12,496). Sleep duration was categorized as <6 hours, 6–8 hours, or >8 hours. Cardiovascular risk was assessed using the Framingham risk score (FRS) and classified as low-to-moderate (≤20%) or high (>20%). Complex-sample logistic regression models were applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for high FRS according to sleep duration.

Results: A U-shaped association was observed between sleep duration and elevated cardiovascular risk. Compared with the reference group (6–8 hours), both short (<6 hours) and long (>8 hours) sleep durations were significantly associated with higher odds of high cardiovascular risk. The association was more pronounced among individuals with short sleep duration.

Conclusions: Both short and long sleep durations were independently associated with elevated 10-year cardiovascular risk among Korean adults. These findings suggest that sleep duration may represent a modifiable lifestyle factor relevant to cardiovascular risk stratification and prevention.