The goal of this clinical trial is to learn about the effect of intraoperative esketamine infusion on postoperative sleep disturbance(PSD) of patients undergoing spinal surgery. The main aims to answer are:

• To explore the effect of intraoperative infusion of esketamine on the incidence of postoperative sleep disturbance and sleep quality in patients undergoing spinal surgery.
• To explore the effect of intraoperative infusion of esketamine on postoperative pain, anxiety and depression ; Participants will be patients undergoing spinal surgery with general anesthesia at Beijing Tiantan Hospital. 0.3mg/kg/h esketamine or saline will be infused during surgery . The incidence of sleep disturbance , sleep quality, pain scores, hospital anxiety and depression scores and perioperative adverse events after surgery will be investigated.

Inclusion Criteria:

• 18-65 years old,
• American Society of Anesthesiologist (ASA) Physical Status classification I to III ;
• Patients scheduled to undergo elective spinal surgery under general anesthesia;
• Signed informed consent ;

Exclusion Criteria:

• BMI > 35kg / m2 ;
• Severe lesions of important organs and systems ;
• The estimated duration of surgery is more than 4 hours
• Patients who were retained tracheal intubation or admitted to intensive care unit (ICU) postoperatively.
• History of adverse reactions or contraindications to ketamine and esketamine ;
• Cognitive dysfunction, communication disorders ;
• Refused to participate in this study.

All data generated or analysed during this study will be included in published article. The data that support the findings of this study are available from the corresponding author, HW upon reasonable request.

The data that support the findings of this study are available from the corresponding author, HW upon reasonable request.