Association between circadian syndrome and frailty in middle-aged and elderly people: a longitudinal study

Background This study aimed to investigate the cross-sectional and longitudinal associations between Circadian syndrome (CircS) and frailty using nationally representative data from CHARLS (China Longitudinal Study of Health and Retirement).Methods The cross-sectional study enrolled 9584 Chinese adults aged 45 years and older in 2011. Logistic regression models were used to investigate the associations of CircS with frailty status and frailty index. The longitudinal study enrolled 6363 eligible participants. Cox regression models were used for longitudinal association analysis and subgroup analyses.Results Cross-sectional analysis showed that CircS was positively correlated with the frailty index (β = 0.041, 95% CI: 0.036-0.045, p < 0.001) and frailty status (OR = 2.008, 95% CI: 1.770-2.279, p < 0.001). During the 7-year follow-up, a total of 1,833 participants (28.81%) developed frailty. CircS was significantly associated with the risk of developing frailty status (HR = 1.499, 95% CI: 1.367-1.644, P < 0.001).Conclusion This study provides the first longitudinal evidence that CircS is a significant predictor of frailty among older adults. These findings underscore the importance of circadian health in the aging process and suggest that targeting CircS through lifestyle and behavioral interventions may represent a promising strategy for frailty prevention and management.