An interventional study of Transcutaneous Auricular Vagus Nerve Stimulation and Sham Stimulation in Healthy Volunteers, sponsored by Sinop University. Not yet recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-16.
Sponsored by Sinop University · Not applicable, Interventional, and Basic science
This study aims to evaluate how different heart rate variability (HRV) recording durations reflect autonomic nervous system responses during transcutaneous auricular vagus nerve stimulation (taVNS) in healthy adults. In a randomized, sham-controlled crossover design, participants will attend two separate sessions and receive both active taVNS and sham stimulation in randomized order. During each session, a continuous 10-minute HRV recording will be obtained, and 1-minute, 5-minute, and 10-minute analysis windows will be compared. Blood pressure and pulse will also be measured before and after stimulation. The study will investigate whether shorter or longer HRV recording durations provide results comparable to the standard 5-minute recording and which duration most reliably detects autonomic changes during taVNS.
The vagus nerve plays a central role in autonomic regulation, and heart rate variability (HRV) is a widely used noninvasive marker of autonomic nervous system activity. Transcutaneous auricular vagus nerve stimulation (taVNS) has increasingly been used in experimental and clinical research as a noninvasive method to modulate vagal activity. Although previous studies suggest that taVNS may influence parasympathetic activity, HRV measurement duration remains an important methodological issue. Standard short-term HRV analysis is commonly based on 5-minute recordings, but ultra-short and longer recordings are also used, and their validity during taVNS has not been sufficiently clarified.
This study is designed to determine whether different HRV recording durations provide comparable and reliable information during taVNS. The study will use a randomized, sham-controlled crossover design. Healthy adult participants will attend two sessions separated by a washout period of 48 to 72 hours. In one session, participants will receive active taVNS; in the other, they will receive sham stimulation. The order of sessions will be randomized.
During each session, HRV data will be collected continuously for 10 minutes using a Polar H10 chest strap. From this single uninterrupted recording, 1-minute, 5-minute, and 10-minute analysis windows will be derived. HRV parameters from time-domain and frequency-domain analyses will be calculated. Blood pressure and pulse will be measured before and after the intervention using an automated upper-arm blood pressure monitor.
Active taVNS will be applied to the cymba conchae region of the ear using commonly reported stimulation parameters. Sham stimulation will be delivered with the same device and similar sensory conditions, but at a non-vagal ear location to minimize physiologic vagal effects. This design is intended to control for nonspecific sensory and expectation-related effects.
The primary objective is to assess whether the standard 5-minute HRV recording during taVNS detects autonomic effects compared with sham stimulation. Secondary objectives are to examine the agreement between 1-minute, 5-minute, and 10-minute HRV measurements and to evaluate whether shorter or longer recordings provide additional methodological value. The relationship between HRV findings and hemodynamic responses, including blood pressure and pulse, will also be explored. This study may help identify the most appropriate HRV recording duration for future taVNS research and contribute to methodological standardization in this field.
Sinop University is the lead sponsor of 30 studies on the registry; 11 are open to participants now.
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Participants assigned to this sequence will receive active transcutaneous auricular vagus nerve stimulation (taVNS) during the first session and sham stimulation during the second session, with a 48- to 72-hour washout period between sessions.
Device: Transcutaneous Auricular Vagus Nerve Stimulation
Participants assigned to this arm will receive sham stimulation during the first session and active transcutaneous auricular vagus nerve stimulation (taVNS) during the second session, with a 48- to 72-hour washout period between sessions.
Device: Sham Stimulation
Active transcutaneous auricular vagus nerve stimulation will be applied bilaterally to the cymba conchae region of the ear using a transcutaneous stimulation device. Stimulation will be delivered for 10 minutes with a frequency of 25 Hz, a pulse width of 200 to 300 microseconds, and an individually adjusted intensity that is clearly perceptible but not painful. Heart rate variability will be recorded continuously during the intervention.
Also known as: taVNS
Sham stimulation will be delivered for 10 minutes using the same transcutaneous stimulation device and similar stimulation settings as the active intervention, but the stimulation will be applied to a non-vagal ear region, such as the earlobe or helix, to minimize physiologic vagal effects while maintaining similar sensory input. Heart rate variability will be recorded continuously during the intervention.
Also known as: Sham taVNS
Difference in 5-minute lnRMSSD During Active taVNS Compared With Sham Stimulation
The primary outcome is the between-condition difference in 5-minute heart rate variability, assessed by lnRMSSD derived from the continuous RR interval recording obtained during the 10-minute intervention period. The 5-minute analysis window is the prespecified standard short-term HRV measure used to compare active transcutaneous auricular vagus nerve stimulation with sham stimulation.
Time frame: During the 10-minute intervention period at each study session
Agreement Between 1-minute and 5-minute HRV Measurements During Active taVNS
Agreement between ultra-short 1-minute and standard 5-minute HRV measurements obtained from the same continuous RR recording during active taVNS will be assessed using predefined agreement analyses.
Time frame: During the 10-minute intervention period at each active taVNS session
Comparison of 10-minute and 5-minute HRV Measurements During Active taVNS
HRV parameters derived from 10-minute and 5-minute analysis windows of the same continuous RR recording during active taVNS will be compared to determine whether the longer recording provides additional physiologic sensitivity or discriminatory value.
Time frame: During the 10-minute intervention period at each active taVNS session
Effect of Recording Duration on HRV Differences Between Active taVNS and Sham Stimulation
Differences between active taVNS and sham stimulation will be evaluated across 1-minute, 5-minute, and 10-minute HRV analysis windows to determine whether recording duration influences the detection of autonomic effects.
Time frame: During the 10-minute intervention period at each study session
Change in Systolic and Diastolic Blood Pressure After Active taVNS Compared With Sham Stimulation
Systolic and diastolic blood pressure will be measured before and immediately after each intervention session to assess hemodynamic responses to active taVNS and sham stimulation.
Time frame: Immediately before and immediately after each 10-minute intervention session
Change in Pulse Rate After Active taVNS Compared With Sham Stimulation
Pulse rate will be measured before and immediately after each intervention session to assess hemodynamic responses to active taVNS and sham stimulation.
Time frame: Immediately before and immediately after each 10-minute intervention session
Plan to share: No
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