Effects of Preoperative Sleep Disorders on Perioperative Anesthesia Depth and Recovery Quality in Patients Undergoing Noncardiac Surgery

Inclusion Criteria: 1. \- Aged 18 to 65 years, with American Society of Anesthesiologists (ASA) physical status classification Ⅰ-Ⅲ; 2. Elective non-cardiac surgery with an expected operative duration longer than 2 hours; 3. Preoperative Mini-Mental State Examination (MMSE) score ≥ 24; 4. Completion of the Pittsburgh Sleep Quality Index (PSQI) assessment 1 day before surgery; 5. Absence of severe cardiac, hepatic, renal or cerebral diseases, and no history of psychiatric or neurological disorders; 6. Voluntary provision of written informed consent. Exclusion Criteria: 1. Preoperative severe cognitive dysfunction, history of traumatic brain injury or stroke; 2. Long-term regular use of sedative-hypnotics, antidepressants or antipsychotics; 3. Intraoperative massive hemorrhage, cardiac arrest, or severe hypoxemia (SpO₂ \< 90% lasting for more than 5 minutes); 4. Inability to cooperate with EEG monitoring or scale evaluation; 5. Pregnancy or breastfeeding status. Drop-out Criteria : 1. Cancellation of scheduled surgery/anesthesia or postoperative admission to the intensive care unit (ICU); 2. Patient withdrawal of study participation; 3. Intraoperative massive hemorrhage, cardiac arrest, or severe hypoxemia (SpO₂ \< 90% lasting for more than 5 minutes); 4. Development of severe postoperative complications; 5. Incomplete data collection or voluntary trial withdrawal.