PROJECT SUMMARY Dysregulated sleep and circadian disruption are common among adults in the United States. An estimated 30-50% of adults endorse some form of sleep-related problem, such as short sleep duration (<6 hours/night), poor sleep quality, presence of insomnia symptoms, or an early or late chronotype (i.e., preference for certain sleep and wake time) that is at odds with the dominant societal social clock. These sleep problems are being increasingly implicated as significant contributors to lower cardiovascular health (CVH) and thus subsequently higher cardiovascular disease (CVD) morbidity and mortality. For example, short sleep duration, insomnia symptoms, and evening chronotype are associated with a number of components to CVH, including obesity, diabetes, and lower diet quality. Consequently, these same sleep- related factors are associated with a higher risk for new-onset CVD, including coronary heart disease and heart failure. There are significant health disparities for sleep health, CVH, and CVD. Dysregulated sleep, poorer CVH, and higher CVD morbidity and mortality are disproportionately distributed across populations, with individuals of non-white racial/ethnic groups and those overly burdened by socio-, economic-, and environmental disadvantage faring the worst. Despite these parallel problems among the same populations and the significant extant literature on the sleep-CVD association, there is a dearth of research on potential ways in which sleep disparities contribute to CVH and CVD disparities and how to simultaneously address both of these connected problems. Therefore, the overall research-related goal of this two-year Diversity Supplement proposal is to address the current need for research on the intersection of sleep and CVD disparities in diverse populations through the following aims: 1) determine associations of sleep factors, chronotype, and chronotype-sleep timing alignment with left ventricular mass index, 2) determine associations of sleep factors, chronotype, and chronotype-sleep timing alignment with potential behavioral (physical activity, diet quality, alcohol use, smoking) and biological (cortisol) mechanisms, and 3) determine whether these associations differ by individual- and geocoded, community-level social determinants of health. In parallel to this research, the overall training-related goal of this Supplement is to support Dr. Brittanny Polanka, PhD in receiving necessary mentorship and career development guidance to become an independent, extramurally-funded principal investigator in the field of cardiovascular behavioral medicine. In collaboration with a mentorship team including the expertise of Drs. S. Justin Thomas, Marwah Abdalla, and Mercedes Carnethon, an individualized career development plan has been created to address mentee training gaps in measurement and processing of objective sleep and circadian data, use of subclinical assessment markers derived from echocardiography, and methodologic...