Suvorexant and Sleep/Delirium in ICU Patients

Investigators will evaluate the efficacy of postoperative oral suvorexant treatment on nighttime wakefulness after persistent sleep onset (WASO) among adult cardiac surgical patients recovering in the cardiac intensive care unit (ICU). The study include patients ≥ 60 years old undergoing coronary artery bypass graft surgery (CABG), with or without valve surgery (aortic or mitral). Patients will receive either oral suvorexant or placebo for 7 nights starting the night after extubation. The primary hypothesis is that suvorexant compared with placebo decreases WASO, as measured by a specialized electroencephalogram (EEG), the SedLine monitor, during the first night in the cardiac ICU. Investigators will also assess total sleep time (TST), time to sleep onset (TSO), and postoperative delirium and delirium-free days.