Circadian syndrome predicts all-cause mortality risks in adults aged ≥40 years: evidence from US and Chinese national population surveys

Background Circadian syndrome (CircS), a condition characterized by circadian rhythm disruption due to modern lifestyle factors, have been identified as a stronger predictor for the development of cardiovascular disease (CVD). However, its association with all-cause mortality in middle-aged and elderly populations remains unclear. This study aimed to investigate the impact of CircS on all-cause mortality risk in middle-aged and elderly adults. Methods Using data from two population-based cohorts (China Health and Retirement Longitudinal Study [CHARLS, n = 12,106] and the National Health and Nutrition Examination Survey [NHANES, n = 17,096]), we defined CircS as MetS components combined with short sleep duration and depression. The primary outcome was all-cause mortality, which was assessed through standardized follow-up questionnaires. Cox proportional hazards models were employed to evaluate all-cause mortality risks. Results Among 29,202 participants, the prevalence of CircS was 27.70% (CHARLS) and 25.90% (NHANES). After full adjustment for covariates, CircS was independently associated with elevated risk of all-cause mortality in both cohorts (CHARLS: HR = 1.170, 95% CI 1.040–1.315; NHANES: HR = 1.151, 95% CI 1.054–1.258). Notably, this association was more significant in US patients with CircS who aged 40 to 59 years, who are drinkers, who have normal waist circumference. Conclusion CircS was independently associated with elevated risk of all-cause mortality in both Chinese and US adults aged ≥ 40 years, particularly in US patients with CircS who aged 40 to 59 years, who are drinkers, who have normal waist circumference.