Transcutaneous auricular vagus nerve stimulation for improving moderate-to-severe sleep disturbance after orthognathic surgery: a randomized, double-blind, placebo-controlled clinical trial

INTERVENTION: The TaVNS group:Transcutaneous auricular vagus nerve stimulation (taVNS) : pulse width 250µs, frequency 30Hz, duty cycle 50%, duration 30min, and stimulation intensity set to the maximum current tolerable by the skin, administered the night before surgery, preoperatively, and on the night of surgery.;The control group:Sham transcutaneous auricular vagus nerve stimulation (Sham taVNS): pulse width 250µs, frequency 30Hz, duty cycle 50%, duration 30min, electrical output was limited to an initial 30second pulse to simulate the sensation, followed by zero effective current for the remainder of the session, administered the night before surgery, preoperatively, and on the night of surgery.; CONDITION: Moderate‐to‐severe postoperative sleep disturbance PRIMARY OUTCOME: Incidence of moderate to severe sleep disorders on the first postoperative night; SECONDARY OUTCOME: Incidence of moderate to severe sleep disorders on the second postoperative night;Sleep quality on the first postoperative night;Sleep quality on the second postoperative night;postoperative wound pain;postoperative sore throat;postoperative nausea and vomiting; INCLUSION CRITERIA: 1. Aged >= 18 years, either sex, with BMI < 30 kg/m²; 2. ASA level I or II; 3. Scheduled to undergo orthognathic surgery under general anesthesia; 4. Voluntarily participate in this study and sign the informed consent form.