Association of Clinical, Psychological and Lifestyle Factors with Disparities in Sleep: The CARDIA Sleep Study

Study Objectives To determine the degree to which clinical, psychosocial and lifestyle factors are associated with racial disparities in sleep health. Methods The sleep ancillary to the Coronary Artery Risk in Young Adults (CARDIA) Study included 7 days of wrist actigraphy, home sleep apnea testing and questionnaires. The CARDIA study collected clinical (body mass index, hypertension, diabetes, cardiovascular disease, heart failure, chronic kidney disease), psychosocial (education, household size, depressive symptoms) and lifestyle (smoking, alcohol, physical activity) information in Black and White adults over 35 years. Sleep characteristics included: sleep duration, sleep percentage, fragmentation, sleep timing, sleep regularity, rest activity rhythms, insomnia severity, and sleep apnea (apnea-hypopnea index ≥15). In cross-sectional and longitudinal analyses, we calculated how much the racial difference in sleep was reduced after adjusting for each risk factor domain (expressed as % reduction). Results There were 899 participants aged 53-69 years; 41% were Black and 63.4% were women. Most sleep characteristics were significantly worse in the Black participants. In cross-sectional analyses, the clinical domain resulted in the largest reduction in racial differences, ranging from 4.2% for sleep duration to 118.9% for sleep apnea. In longitudinal analyses, the clinical domain resulted in the largest reduction in racial differences, ranging from 5.2-65.5%. Psychosocial factor adjustment had largest reduction in racial differences in sleep percentage (by 17.8%) and sleep regularity (by 23.4%). Conclusions These findings suggest that clinical and to a lesser degree psychosocial domains should be the foci of future work aimed at understanding and ultimately reducing racial sleep disparities.