Orexin Antagonist

The goal of this clinical trial is to learn about how certain medications used to treat insomnia (e.g., Lemborexant) impact sleep, mood, and behavior in men and women with Opioid Use Disorder who are taking prescribed buprenorphine. The main questions it aims to answer are: 1. What is the effect of the study drug (lemborexant) on sleep outcomes? 2. What is the effect of the study drug (lemborexant) on impulsive behavior (as measured by computer test performance)? 3. What is the effect of the study drug (lemborexant) on mood and other behavior? Researchers will compare lemborexant to placebo (e.g., sugar pill) to see if participants assigned to 8 weeks of treatment with lemborexant have greater improvements on the measures listed above. Participants will take the study medication (or placebo) each night for 8 weeks and be asked to come for a total of 23 study visits. Most of these visits will be very short (15-30 minutes). The longer visits will include the screening visit (about 2-3 hrs), baseline visit (about 2.5 hrs), and the post-medication visit (about 2 hrs). Study visits will include things like taking surveys about sleep, drug use, and mood, completing urine drug testing, checking vital signs (e.g., blood pressure), and completing interviews with the study staff. Participants will also be asked to provide two blood samples (one during screening and one after taking the medication). For three two-week periods, participants will be asked to wear a watch to track sleep at home, and to keep a log of sleep and wake times.

Post-operative delirium is a common complication following cardiac surgery and is associated with increased 1 year mortality. Currently there are no drug therapies to prevent delirium. Orexin is a neuromodulator thought to play an important role in disordered sleep, one of the instigators of delirium. Lembrorexant is an orexin antagonist, originally approved for sleep, that may also reduce the incidence of delirium. The Investigators propose a pilot study to determine the feasibility of a randomized controlled trial comparing Lembrorexant to placebo in patients following cardiac surgery in reducing the incidence of delirium, and improving sleep.