RecruitingPhase 2Drug trialSuvorexant as an Adjunct to Buprenorphine in Persons Who Use FentanylThis is a 4-week, randomized-controlled trial of suvorexant vs placebo in persons with opioid use disorder who have recent fentanyl exposure. Participants will first undergo a 5-day residential phase wherein participants are stabilized on sublingual buprenorphine/naloxone, followed by a 3-week outpatient phase wherein participants are maintained on sublingual buprenorphine/naloxone and transitioned to extended-release buprenorphine).