Inclusion Criteria:  Patients undergoing a scheduled surgery (laparotomy, hepatobiliary surgery, gynecologic surgery, and/or urologic surgery procedures) at Indiana University Health University Hospital that is expected to have at least a 3 day post-operative hospital stay. ASA class 1, 2, 3, or 4. Age 65 years or older. Male or Female Surgical procedure requiring general anesthesia.  Exclusion Criteria:  Any previous diagnosis of dementia or other cognitive impairment. Any patient undergoing emergency surgery. Any patient undergoing surgery who is currently an inpatient. Patient refusal to participate in study. Any patient undergoing surgery that would prevent placement of the Sedline monitor leads (for example - surgery on the patient's forehead/scalp). Any physical, mental, or medical conditions which, in the opinion of the investigators, may confound the ability to assess the patient for delirium in the post-operative period.