Non-Invasive Transcutaneous Auricular Vagus Nerve Stimulation Applied at Different Durations in Healthy Adults

This randomized, participant-blinded, sham-controlled interventional study aims to compare the acute effects of non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) applied at different durations on autonomic nervous system responses in healthy adults. Participants will be assigned to either an active taVNS group or a sham stimulation group. Within each group, participants will complete three separate study visits in which stimulation will be applied for 5, 10, and 15 minutes in randomized order, with 48- to 72-hour washout intervals between visits. Heart rate variability, heart rate, blood pressure, respiratory rate, and subjective discomfort will be assessed immediately before and after each intervention session. The study is designed to determine whether the acute autonomic effects of taVNS vary according to stimulation duration and whether a duration-related response pattern can be identified.