This study explores the association between cerebral overperfusion and postoperative delirium (POD) in cardiac surgery patients. Continuous monitoring of cerebral blood flow, oxygen levels, and brain activity revealed increased middle cerebral artery velocity (MCAV) in patients with POD, despite stable oxygen saturation and autoregulation. The findings suggest that impaired cortical metabolism may render the brain vulnerable to overperfusion during surgery, increasing POD risk.