Investigating the Efficacy of Auricular Vagus Nerve Stimulation in Counteracting Fatigue and Enhancing Cognition under High-Altitude Exposure

INTERVENTION: Rapid Ascent taVNS Group:Auricular Vagus Nerve Stimulation;Rapid Ascent Sham Group:Earlobe Vagus Nerve Stimulation;Resident taVNS Group:Auricular Vagus Nerve Stimulation;Resident Sham Group:Earlobe Vagus Nerve Stimulation; CONDITION: none PRIMARY OUTCOME: Electrocardiogram;Electroencephalogram;Photoplethysmography;SpO2;RSP;Lake Louise Score;Fatigue Severity Scale;Cognitive Function Assessment; INCLUSION CRITERIA: 1. Aged between 18 and 45 years, regardless of gender. 2. Body Mass Inde X(BMI) between 18.5 and 28.0 kg/m² (to exclude the influence of obesity or malnutrition on physiological indicators). 3. For rapid‐ascent populations: No history of high‐altitude exposure (defined as no stay exceeding 24 hours in an environment above 3000m). For resident populations: High‐altitude exposure (above 3000m) for at least 3 months (to avoid the residual stress effects of rapid ascent). 4. Confirmed to be in good health without severe underlying diseases, as verified through physical examination (blood pressure, heart rate, cardiopulmonary auscultation) and laboratory tests (complete blood count, liver and kidney function). 5. Normal hearing (able to understand trial instructions clearly), and no deformities, inflammation, or trauma of the auricle (to ensure proper electrode placement). 6. No history of neurological or psychiatric disorders (e.g., epilepsy, depression,