Daridorexant to Prevent Post-cardiotomy Delirium

Inclusion Criteria: * ≥ 60 yrs; * having surgical aortic valve surgery or coronary artery bypass graft surgery at Strong Memorial Hospital; * can provide consent; * able to speak, read,and write English (as the instruments, including semi-structured interviews, used in this protocol have been validated in English); * family member or close friend for collateral. Exclusion Criteria: * Prior cardiotomy * Infectious endocarditis * Emergency surgery * Delirium at baseline (positive 3D-CAM) * Auditory or visual impairment that prevents study procedures * Alcohol or substance misuse (CAGE-AID score ≥ 2) * Psychotic disorder * Dementia-level deficits (TICS \< 27) * Use of a prescription sleep aid at least every other night * Use of a strong CYP3A4 inhibitor (e.g., ceritinib, clarithromycin, cobicistat, idelalisib, itraconazole, ketoconazole, nefazodone, nelfinavir, posaconazole, ritonavir, telithromycin, voriconazole) * Daridorexant intolerance * Severe kidney or liver impairment (Child-Pugh ≥7, Cockcroft-Gault \<30 mL/min, or on dialysis) * Narcolepsy * Suicidal ideation at baseline * Any condition that, in the PI's opinion, compromises patient safety or data quality * Additional exclusions for the NLP exploratory aim: history of traumatic brain injury or head concussions with loss of consciousness, use of corticosteroids, or history of major neurological disease or brain surgery