Mechanisms of Risky Alcohol Use in Young Adults: Linking Sleep to Reward- and Stress-Related Brain Function

Inclusion Criteria: 1. 18-24 years of age; 2. NIAAA criteria for past-month high-risk drinking (i.e., ≥ 4 drinks/day or ≥ 8/week for women, ≥ 5 drinks/day or ≥ 15/week for men); 3. short and late sleep (weekday sleep duration ≤ 7.5 hours and bedtime ≥ 24:00 (midnight); n=60) or long and early sleep (weekday sleep duration \> 7.5 hours and bedtime ≤ 24:00 (midnight); n=30); 4. at least moderate lifetime exposure to stressors (≥ 2 events on the 20-item Adult Stress and Adversity Inventory-Screener); 5. not currently in high school; and 6. English language fluency. Exclusion Criteria: 1. Severe alcohol use disorder (AUD) and/or substance use disorder (SUD), defined as ≥6 AUD/SUD criteria in the Diagnostic and Statistical Manual-5; 2. acute alcohol intoxication on the days of the laboratory post-intensive visits, operationalized as a blood alcohol concentration of .02 or higher during Breathalyzer saliva screen; 3. current clinician-provided diagnosis of narcolepsy or idiopathic hypersomnia; 4. lifetime diagnosis of bipolar or schizophrenia spectrum disorder; 5. certain medical conditions (e.g., serious neurological disorder, heart failure or serious trouble, history of head injury with unconsciousness \> 5 minutes); 6. conditions that are contraindicated for MRI (e.g., ferrous metal in the body); 7. positive screen for participant-reported eye disease, epilepsy, or photosensitizing medications that are contraindicated during the manipulation condition when bright light is administered (e.g., psychiatric neuroleptic drugs \[e.g., phenothiazine\], psoralen drugs, antiarrhythmic drugs \[e.g., amiodarone\], antimalarial and antirheumatic drugs, porphyrin drugs used in photodynamic treatment of skin diseases); 8. use of melatonin if participant is not willing to discontinue use for the duration of the study. We will schedule around (i.e., delay appointments as needed) to avoid the timeframe of the following events: 1. urgent suicide risk, defined by moderate/severe risk per CSSR and clinician determination that current risk requires immediate action; 2. travel across two or more time zones within the month prior to the overnight study visits. 3. begin/end a prescribed medication within 2 months of the observational study; 4. medication dose changes within the timeframe calculated as 5x the drug's half-life \[the time to reach pharmacokinetic steady-state\] before the initiation of the observational or experimental studies; 5. participant-anticipated changes in prescribed medications or medication dosing during the observational or experimental studies.; 6. current symptoms of an airborne infectious illness (e.g., COVID) prior to laboratory visits. Participants with positive breathalyzer screen (blood alcohol level \> .02) will be rescheduled for an alternative overnight visit date.