This randomized, participant-blinded, sham-controlled crossover study aims to investigate the acute effects of different frequency applications of transcutaneous auricular vagus nerve stimulation (taVNS) on autonomic physiological responses in healthy adults. Participants will receive sham (0 Hz), 10 Hz, 25 Hz, 50 Hz, and 100 Hz taVNS in separate sessions with washout periods between visits. Heart rate variability, blood pressure, pulse rate, respiratory rate, and subjective discomfort will be assessed before and after each intervention session.
Healthy adults aged 18 to 40 years
No known neurological, cardiovascular, respiratory, or metabolic disease
Able to understand study procedures and provide written informed consent
No active infection, open wound, or dermatological lesion in the ear region that would interfere with taVNS application
History of cardiac arrhythmia, pacemaker, or any implanted electronic medical device History of hypertension, diabetes, chronic pulmonary disease, epilepsy, or systemic disease affecting autonomic nervous system function
Regular use of medications that may affect autonomic function (e.g., beta-blockers, antidepressants, antiarrhythmics)
Intense physical exercise within the previous 24 hours
High caffeine or alcohol intake within 12 hours prior to assessment