Suvorexant for Treatment of AUD and PTSD

Inclusion Criteria: * Age between 21 and 65. * Meet current (i.e., past 12-month at Day -7/-6) DSM-5 diagnostic criteria for moderate or severe AUD as determined by the MINI. * Currently experiencing PTSD symptoms at screening (Day -7/-6) as indicated by PCL-5 cut-score \> 30. * Intrinsic motivation to reduce or quit drinking (defined as self-reported intention at screening to reduce or quit drinking within the next 6 months) and to receive PTSD treatment. * Must have an ISI score equal to or \> 7 (subthreshold insomnia). ISI score below 7 at screening will not be included or proceed beyond the screening day. * Agree to abstain from all other sleep medications (starting at Day -7). * Have a place to live in the 2 weeks prior to randomization (Day 0) and not be at risk that s/he will lose his/her housing in the next month. Exclusion Criteria: * A current (past 12-month at Day -7/-6) DSM-5 diagnosis via the MINI of substance use disorder for any substances other than alcohol, nicotine, or marijuana (\< moderate level on DSM 5). * A lifetime DSM-5 diagnosis via the MINI of schizophrenia, bipolar disorder, or psychotic disorder. * Positive urine test for any recreational drugs other than marijuana at screening (Day -7/-6). * Current clinically significant alcohol withdrawal (i.e., score ≥ 10 on the CIWA-Ar). * Currently pregnant, nursing, or no reliable method of birth control (females only). * Any clinically significant medical condition that would preclude safe participation in the study (e.g. narcolepsy, seizure disorder, or other clinically significant cardiovascular, hematologic, hepatic, renal, neurological, or endocrine disorders). * Use of suvorexant (within 30 days of Day -7). * Currently on prescription medication that contraindicates use of suvorexant (including moderate or strong Cytochrome P450 3A modulators (CYP3A inhibitors and inducers)) * Hepatic insufficiency (AST/ALT \> 5x upper limit of normal (ULN)). * Suicidal Ideation determined by greater than moderate Columbia Suicide Severity Rating Scale. * Inability to provide evidence of 48-hour alcohol abstinence (self-report, BrAC, EtG) at Day 0 AND failure after second attempt at 48-hour abstinence.