Association of Rest‐Activity Rhythm and Sleep Regularity With Cardiometabolic Disease in the CARDIA Study

Background Disrupted circadian rhythms are associated with cardiometabolic disease. We examined associations between rest‐activity rhythms and cardiometabolic disease by race. Methods In cross‐sectional analysis of the CARDIA (Coronary Artery Risk Development in Young Adults) sleep ancillary study (2020–2023), 861 participants wore wrist actigraphy for 7 days. Sleep Regularity Index and rest‐activity rhythm measures were calculated: interdaily stability, intradaily variability, relative amplitude, and most active 10‐hour and least active 5‐hour period start times. Cardiometabolic disease markers included body mass index, waist circumference, blood pressure, hypertension, fasting glucose, estimated insulin resistance, and diabetes. Linear regression models with interaction terms evaluated effect modification by race. Results Among 354 Black and 507 White participants, the most consistent associations were between anthropometric markers and rest‐activity rhythms. Except for most active 10‐hour start, remaining indices and Sleep Regularity Index were associated with body mass index with β coefficients ranging from −1.74 to 0.86, consistent with our hypothesis that weaker rest‐activity rhythms relate to larger body mass index. There was some effect modification by race ( P <0.01), with relative amplitude showing stronger associations with body mass index in White ( β =−2.63 [95% CI, −3.34 to −1.93]) versus Black ( β =−1.24 [95% CI, −1.97 to −0.50]) participants. Patterns, including effect modification for relative amplitude, were similar for waist circumference. Disrupted circadian indices were associated with glycemic markers, with findings generally consistent by race. Associations between rest‐activity rhythms and blood pressure were less consistent overall and by race. Conclusions Less robust rest‐activity rhythms and irregular sleep were associated with less favorable anthropometric and glycemic markers but weakly associated with blood pressure, with few racial differences.