Effect of the orexin receptor antagonist, suvorexant, on sleep architecture in the early postoperative period following cardiac surgery: a randomized controlled trial.

backgroundPatients recovering from cardiac surgery in the intensive care unit (ICU) do not sleep well. Commonly used sedative-hypnotic medications can disrupt sleep architecture and increase the risk of delirium in critically ill patients after surgery. The orexin receptor antagonist suvorexant, improves sleep onset and duration in patients with chronic insomnia. We hypothesized that suvorexant improves sleep onset and duration while also reducing the incidence of delirium after cardiac surgery.

methodsThis multicentric, double-blind, randomized controlled trial was conducted at two university-based cardiac ICUs. One hundred adult patients were enrolled after admission to the ICU following cardiac surgery. Enrollment occurred between March 2020 and February 2025. Participants were randomized to receive either a once daily oral dose of suvorexant 20 mg or placebo. Treatment began on the first night after extubation and continued until hospital discharge or for a maximum of seven days, whichever occurred first. Sleep was recorded using an electroencephalography (EEG) monitor (SedLine, Masimo Corp., California, USA) on the first night after extubation and was scored blindly by an experienced registered polysomnographic technologist. The primary outcome was wakefulness after persistent sleep onset (WASO). Sleep onset was defined as the first 30-second epoch classified by rapid eye movement (REM) or non-REM stages 1, 2, 3 after lights off. Wakefulness was defined as an awake period of 30s or longer. Sleep questionnaires were administered and delirium screenings were conducted every morning until hospital discharge.

resultsOne hundred patients were randomized to receive suvorexant (n = 49) or placebo (n = 51). EEG analysis indicated that neither the median [inter-quartile range] nighttime WASO (200.7 [112.1, 328.4] minutes vs. 184.2 [80.4, 304.2] minutes; p = 0.33) nor total sleep time (224.0 [112.0, 379.0] minutes vs. 253.0 [68.0, 420.0] minutes; p = 0.92) differed significantly between the groups. There was no significant difference in rescue medication (melatonin, dexmedetomidine, benzodiazepine) utilization between the groups. Subjective sleep quality, incidence of delirium, and delirium-free days did not differ between the two groups. TRIAL REGISTRATION NUMBER: Clinical Trials Registry no. NCT04092894, Registration Date 09/17/2019.

conclusionsAmong patients recovering in the ICU who underwent cardiac surgery with cardiopulmonary bypass, the suvorexant treatment did not affect wakefulness after sleep onset or post-operative delirium.