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 Development 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 per cent were black and 63.4 per cent 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 per cent for sleep duration to 118.9 per cent for sleep apnea. In longitudinal analyses, the clinical domain resulted in the largest reduction in racial differences, ranging from 5.2 per cent to 65.5 per cent. Psychosocial factor adjustment had largest reduction in racial differences in sleep percentage (by 17.8 per cent) and sleep regularity (by 23.4 per cent). 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. Statement of Significance Research describes poorer sleep health among black adults compared to white adults in the United States. We aimed to identify whether clinical, psychosocial, and lifestyle characteristics were associated with racial sleep disparities in an observational study of 899 adults aged 53-69 years. We included several dimensions of sleep based on wrist actigraphy and a home sleep apnea test. The clinical characteristics were associated with the largest reduction in racial differences in sleep health, suggesting that health-related factors may account for some racial differences in sleep. Psychosocial factors, such as education, household size, and depressive symptoms, were also associated with racial differences in some sleep measures. Future research should test whether improvements in these domains can improve sleep heath and reduce disparities.