7. PROJECT SUMMARY/ABSTRACT The long-term objectives of this proposal are: 1) to evaluate a biobehavioral model of alcohol use disorder (AUD) in young adults with recent high-risk drinking (≥ 4 drinks/day or ≥ 8/week for women, ≥ 5 drinks/day or ≥ 15/week for men) and high lifetime exposure to stressors, and 2) to leverage sleep and circadian function to promote mental health. These objectives are consistent with two key priorities of the National Institute of Alcohol Abuse and Alcoholism (NIAAA): 1) identify mechanisms of AUDs, and 2) improve prevention and treatment for alcohol misuse. The proposed model of AUD posits that sleep duration and/or timing moderate the effects of stressful life events on high-risk alcohol use by disrupting reward- and stress-related brain function. The research approach uses two complementary study designs to evaluate the proposed model: 1) an observational study (n=150) that will assess the degree to which short and late sleep predict later reward- and stress-related brain function and alcohol use, and 2) an experimental study (n=100) that will evaluate the extent to which sleep duration and timing affect reward- and stress-related brain function and alcohol use. The sample includes young adults (18-24 years of age) with recent high-risk drinking and high lifetime exposure to stressors (≥20 stressors on a lifetime stress and adversity inventory). Recruitment will be stratified to include young adults with short and late sleep (weekday sleep duration ≤ 6 h & midpoint ≥ 4 am; n=100) versus long and early sleep (weekday sleep duration ≥ 8h & midpoint ≤ 2:30 am; n=50). Both studies include measurement of daily sleep and stressful events for 2 weeks; subsequent laboratory measures of reward- and stress-related brain function and sleep and circadian characteristics; and self-report measures of alcohol use during daily monitoring and 2-month follow-up. The experimental study includes random assignment of young adults with short and late sleep from the observational study to 2 weeks of either: 1) 90 min extension and advance of sleep opportunity and timing (n=50); or 2) typical sleep opportunity and timing (n=50). This research approach will accomplish three specific aims: 1) Evaluate the extent to which sleep duration and/or timing predict reward- and stress-related brain function, and moderate the effects of stressful life events; 2) Establish the extent to which sleep duration and/or timing affect reward- and stress-related brain function, and moderate the effects of stressful life events; and 3) Determine the extent to which changes in reward- or stress-related brain function mediate the associations between sleep duration and/or timing and alcohol use. The investigative team has expertise in the etiology and prevention of AUD in young adults, including specific expertise in the impact of sleep and stressful life events on the stress and reward systems that contribute to AUD. All three investigators are also licensed psychologists who are committed to translating research on the mechanisms of psychopathology to preventative interventions.

8. PROJECT NARRATIVE Young adults experience a confluence of major risk factors for alcohol use disorder, including exposure to stressful life events, insufficient sleep, and late sleep timing. This research will use biobehavioral approaches to generate understanding about the linkages between stressful life events, sleep duration and timing, and alcohol use in young adults, with a long-term aim of developing effective preventative interventions for alcohol use disorders.