1. To explore whether the combined administration of dexmedetomidine during and after surgery in patients undergoing brain tumor resection is an effective and safe modality to prevent postoperative delirium and improve sleep quality than giving it alone after surgery.
2. To explore whether intraoperative and postoperative administration of dexmedetomidine to patients undergoing brain tumor surgery can reduce postoperative acute pain and prevent chronic pain.
3. To explore whether intraoperative and postoperative administration of dexmedetomidine to patients undergoing brain tumor surgery can provide stable anesthesia depth, hemodynamics and reduce the dose of anesthetics, thereby accelerating patient recovery.

Inclusion Criteria:

• at least 18 years old and less than 80 years old
• receive brain tumor surgery with ASA II~III.

Exclusion Criteria:

• under the age of 18 or over 80
• consciousness unclear
• those who have not signed a consent form
• those with high anesthesia risk ASA IV or higher