Inclusion Criteria:  Aged 18-65 Meets DSM-5 criteria for opioid use disorder (OUD) with evidence of physical dependence on opioids Provides a urine sample that tests positive for fentanyl and/or fentanyl analogues Interest in being maintained on buprenorphine for OUD Plans to reside in current area for study period Achieving a study maintenance dose of >=8mg sublingual buprenorphine/naloxone Willing to comply with study protocol Have no clinically significant chronic medical or surgical disorders or conditions that are judged by the investigators to prevent participation  Exclusion Criteria:  Medically contraindicated for buprenorphine, extended-release (XR)-buprenorphine (Sublocade), or suvorexant (as per medication labels) Pregnant or breast feeding Severe Diagnostic and Statistical Manual (DSM)-5 alcohol, benzodiazepine, or stimulant use disorder or evidence of alcohol/benzodiazepine physical dependence Have a known allergy to the study medications Past 30-day prescribed use of suvorexant for the indication of insomnia Current benzodiazepine or other prescribed medication for the indication of insomnia Urine sample testing positive for benzodiazepine at screening and admission to residential treatment Current narcolepsy, restless leg syndrome or sleep paralysis High risk for current sleep apnea Current (past 30-day) suicidal behaviors  Severe hepatic or renal impairment  aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >3x upper limit of normal (ULN) Total bilirubin >2x ULN Creatinine >1.5x ULN Past year clinically-significant psychiatric condition judged to interfere with study participation Lack of access to stable housing (necessary for electronic pill dispenser charging) Have circumstances that would interfere with study participation (e.g., impending jail)