Circadian Syndrome as a Stronger Predictor of Asthma Than Metabolic Syndrome: Evidence from NHANES 2005–2018

Objective: To examine the association between Circadian Syndrome (CircS) and asthma in U.S. adults and determine whether CircS is a better predictor of asthma than Metabolic Syndrome (MetS) using NHANES 2005–2018 data. Methods: A cross-sectional study was conducted on 13,976 adults from seven NHANES cycles (2005–2018). CircS was defined as the presence of at least four components, including MetS criteria plus short sleep and depressive symptoms. Multivariable logistic regression models adjusted for demographic and lifestyle covariates were used to assess associations of MetS and CircS with lifetime and current asthma. Positive predictive value (PPV) and negative predictive value (NPV) were also calculated. Results: The prevalence of CircS and MetS was 41.5% and 48.9%, respectively. CircS was significantly associated with both lifetime and current asthma in men and women, whereas MetS alone was not significantly associated with asthma after adjustments. CircS alone was linked to a higher likelihood of asthma compared to MetS alone. The PPV for lifetime asthma was higher for CircS (men: 13.4%, women: 19.7%) than for MetS (men: 11.9%, women: 18.6%), while NPVs were similar across groups. Conclusion: CircS may offer a more comprehensive framework than MetS for identifying individuals at elevated risk of asthma. Incorporating short sleep and depression into conventional MetS assessments may help identify adults at higher risk of asthma, though further studies are needed to confirm these findings.