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.