Background: There is an urgent need to translate preclinical findings into pharmacotherapeutic strategies for persons with opioid use disorder (OUD). There is strong preclinical evidence that orexin receptor antagonists can improve sleep, opioid withdrawal, and drug seeking outcomes, yet the effects of orexin receptor antagonists have not been tested in humans with OUD. This randomized-controlled trial aimed to examine whether a dual orexin receptor antagonist, suvorexant, would improve sleep duration, opioid withdrawal, and craving outcomes in persons undergoing a buprenorphine taper. Methods: Persons with OUD were enrolled in a 10-night residential study (clinical trials registration: NCT03789214). All participants were initially inducted and maintained on 8-16mg buprenorphine for three days, then randomized to either placebo, 20mg, or 40mg SUVO before starting a 4-day buprenorphine taper and 4-day post-taper period. Each night participants wore a 3-lead electroencephalography (EEG) device to monitor sleep, and completed daily ratings of opioid withdrawal (Subjective Opioid Withdrawal Scale; SOWS), and 0-100 visual analogue scale (VAS) “Craving”. Chi-square analysis was utilized to assess differences in treatment attrition, intent-to-treat analyses were performed using independent-samples t-tests for differences between suvorexant (collapsed across dose) and placebo during the taper and post-taper period, and one-way ANOVAs were used to assess differences between all three medication groups. Results: Participants (N=38) were 86.8% male, 52.6% white, and had a mean (SD) age of 41.5 (11.3). Participant attrition was not significantly different between placebo (33.3%), 20mg (n=35.7%), and 40mg (n=25.0%) groups. During the buprenorphine taper, participants on suvorexant versus placebo displayed a mean (SE) improvement of 91.2 (36.5) minutes in TST (p=.010), a marginal reduction of 2.3 (2.4) in mean (SE) SOWS (p=.325), and a mean (SE) reduction of 16.7 (8.1) in VAS craving (p=.046). During the post-taper period, participants on suvorexant versus placebo displayed a mean (SE) improvement of 61.2 (30.3) minutes in TST (p=.033), a mean (SE) reduction of 4.5 (2.1) in SOWS (p=.038), and a marginal mean (SE) reduction of 14.6 (9.3) in VAS craving (p=.13). ANOVAs revealed no differences between the 20mg and 40mg doses of suvorexant. Conclusions: This preliminary, dose-finding study demonstrated initial efficacy for suvorexant in improving sleep duration, decreasing craving during opioid tapering, and improving post-taper withdrawal severity. Given the lack of suvorexant dose effects, future studies are needed to examine the FDA-approved dose of 20mg SUVO to confirm its efficacy in treating sleep disturbances, opioid withdrawal, and craving in persons with OUD.