This prospective, randomized controlled trial aims to investigate the perioperative use of lemborexant, an orexin receptor antagonist, for reducing postoperative delirium (POD) in elderly patients undergoing general anesthesia.

Patients in the intervention group will receive lemborexant, while those in the control group will receive a matching placebo. The primary outcome is the incidence of POD within 5 days after surgery. Secondary outcomes include sleep quality on postoperative days 1, 3, and 5, delirium severity and subtype, hospital anxiety and depression scores, quality of emergence from anesthesia, adverse events, and hematological parameters. The expected findings will provide evidence on the safety and efficacy of prophylactic perioperative lemborexant in improving postoperative outcomes in older patients, and will offer a theoretical and practical foundation for future research and clinical application.

Inclusion Criteria:

• Age ≥60 years old;
• ASA classification I to III;
• Patients undergoing elective surgery;
• Sign the informed consent form.

Exclusion Criteria:

• Tracheal intubation is expected to be retained after the operation;
• Previous history of alcohol or drug abuse;
• Severe abnormalities in liver and kidney functions;
• Long-term use of sedative-hypnotic drugs;
• Severe sleep apnea and COPD;
• Inability to cooperate in mental state;
• Craniocerebral surgery
• Pregnant and lactating patients;
• Use drugs that affect orexin metabolism.