PROJECT ABSTRACT Compared to peers in other racial groups, Black emerging adults (18-28 years old) have the highest risks of short sleep duration and cardiovascular disease. This increased risk may be partly explained by greater stress levels resulting from race-related stress (experiences of racial discrimination and heightened feelings of vigilance). Insufficient sleep (longer sleep-onset latency, shorter sleep duration, poorer sleep quality and efficiency, lower amounts of slow-wave sleep) may also lead to greater arterial stiffness (hardening of the arteries, reducing their elasticity and ability to expand and contract as blood is pumped through them) and unfavorable hemodynamic characteristics (physical factors such as high blood pressure, pulse pressure, mean arterial pressure, and heart rate that govern blood flood and heart function), which are well-known risk factors for cardiovascular disease. This supplemental project aims to examine cross-sectional associations between measures of insufficient sleep and race-related stress with arterial stiffness and central hemodynamics in 55 Black emerging adults. The parent R01 grant follows a measurement burst design that includes data collection over 3 bursts (baseline, 6-month follow-up and 12-month follow-up), each lasting 7 days. Measures of arterial stiffness and central hemodynamics will be added to the Day 5, in-laboratory protocol prior to measures of resting energy expenditure. Measures of arterial stiffness (via carotid-femoral pulse wave velocity) and central hemodynamics (via pulse wave analysis) will be captured with the SphygmoCor XCEL system. Insufficient sleep variables will be measured with three methods: sleep diary, actigraphy and polysomnography. Race-related stress will be self-reported. Aim 1 will examine cross-sectional associations between insufficient sleep with arterial stiffness and central hemodynamics. Aim 2 will examine cross-sectional associations between race- related stress with arterial stiffness and central hemodynamics. Our overarching hypothesis is that higher amounts of insufficient sleep and race-related stress will be associated with higher arterial stiffness and unfavorable hemodynamic characteristics. This proposed supplemental project is a logical extension of the goals of the parent grant by adding a clinically relevant outcome (measures of arterial stiffness and central hemodynamics) to the parent R01 project which focuses on sleep, race-related stress, and obesity risk. This proposed supplemental project could also have significant public health implications by investigating initial associations between sleep, race-related stress, and well-known risk factors for cardiovascular disease in Black emerging adults.