PROJECT SUMMARY/ABSTRACT Decades of experimental and epidemiologic research link short sleep duration to adverse cardiometabolic health. Furthermore, emerging research points to direct biological mechanisms linking short sleep duration to cognitive decline and Alzheimer’s disease. Despite decades documenting the deleterious effects of short sleep duration, few studies have sought to improve risk or modify Alzheimer’s disease trajectories by extending sleep. Sleep extension interventions hold promise to improve cardiometabolic disease (CMD) risk, cognition and quality of life. To date, several small studies have demonstrated short term improvements in sleep and CMD risk such as blood pressure and glycemic control. However, existing studies in adults have not addressed whether sleep extension interventions impact cognitive performance and biomarkers of Alzheimer’s Disease risk. The goal of this application is to extend the aims of our parent study to include an examination of the impact of our randomized behavioral sleep extension intervention on Alzheimer’s related biomarkers (blood metabolomics) and cognitive performance measures. In our parent study, we are conducting a randomized controlled trial to test our behavioral sleep extension intervention compared to a health education control group on sleep and CMD risk among adults with prehypertension/stage I hypertension. The 12-month study includes an intervention period (weeks 1-8, weekly intervention), maintenance period (months 2-6, monthly intervention) and follow-up period (no intervention). The primary outcome for the parent study is sleep duration and the main secondary outcome is 24-h ambulatory blood pressure monitoring, which allows us to evaluate both daytime and nighttime blood pressures. The design of this parent study will allow us to examine the acute (8 week) and sustained (12 month) changes in sleep duration, BP and important psychological, behavioral and physiological mediators including self-reported sleepiness, BMI, diet, physical activity, glycemic control and inflammation. The receipt of this Alzheimer’s disease supplement will allow us to extend the scope of our parent study to examine the effects of our sleep extension intervention on blood biomarkers and cognitive performance. Successful completion of this study will provide critical information about the impact of behavioral sleep extension on important measures of health and quality of life needed to incorporate sleep extension into CMD, and potentially Alzheimer’s disease risk interventions. Completion of this supplement will identify potential biochemical pathways and behavioral phenotypes that respond to sleep extension. Identification of these biological and behavioral markers of response to sleep extension has the potential to lead to identification of biomarkers and novel targets to reduce Alzheimer’s Disease risk.