PROJECT SUMMARY/ABSTRACT Only 14% of emerging adults (age 18-25 years) with type 1 diabetes mellitus (T1D) achieve glycemic control (A1C < 7.0%) targets based on national data. Diabetes self-management entails a high degree of involvement and frequent decision making, and coupled with the need to transition to independence, thus emerging adults are also at high risk for poorer diabetes quality of life (DQOL). Complex higher order neurocognitive skills (e.g., psychomotor vigilance and executive function) are needed for successful diabetes self-management. Sleep deficiency (< 6.5h duration) is associated with poorer glycemic control among young adults with T1D, and sleep variability (day-to-day changes in sleep duration) is associated with poorer glycemic control in adolescents and middle-aged adults with T1D. Much of the existing knowledge on sleep in this high-risk age group is based on studies with small cross-sectional descriptive between-subjects designs (N < 30), short measurement time frames (e.g., over 3 days), self-reported sleep measures, and intermittent blood glucose monitoring rather than current monitoring technologies (e.g., continuous glucose monitor [CGM]). Further, A1C alone does not account for glucose variability or hypoglycemia for those with T1D. To our knowledge, only preliminary work has been done to extend sleep in emerging adults with T1D (N = 8 emerging adults). Perfect and colleagues designed an intervention to extend sleep by 1 hour in 111 adolescents which led to an improvement in mean glucose levels from CGM. This application submitted in response to PA-19-129 has the following specific aims: 1. To characterize sleep using self-report (questionnaires, diaries) and objective (actigraphy) methods, glycemic control, and glucose variability among 40 emerging adults with T1D over 14 days (to capture weekend and weekday differences) and explore associations between subjects (1a) and within subjects (1b) (K99 phase); 2. To adapt a behavioral Sleep Self-management (SSM) with Diabetes Self- Management Education (DSME) intervention using a community-engaged approach with 10 emerging adults with T1D (R00 phase); and, 3. To conduct a randomized pilot study to determine feasibility and preliminary effect sizes of the SSM with DSME program in improving neurocognitive function (psychomotor vigilance and executive function), diabetes self-management, DQOL, glycemic control, and glucose variability among 40 emerging adults age with T1D from baseline to post-intervention at 3 and 6 months (R00 phase). To meet these aims, we will enroll 40 emerging adults for each phase of the study. We will use descriptive approaches for the K99 phase and aim 2 of the R00 phase. For aim 3, we will randomize to the SSM with DSME intervention or an attention control (DSME only). Wrist actigraphy measures of sleep, CGM glucose, glycemic control from A1C values, psychomotor vigilance and executive function testing, and self-reported measures of sleep sympt...