Non-Invasive Transcutaneous Auricular Vagus Nerve Stimulation Applied at Different Durations in Healthy Adults (taVNS-DUR)

April 13, 2026 updated by: SEFA HAKTAN HATIK, Sinop University

Comparison of the Acute Effects of Non-Invasive Transcutaneous Auricular Vagus Nerve Stimulation Applied at Different Durations on the Autonomic Nervous System in Healthy Adults: A Sham-Controlled Study

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.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation method in which electrical stimulation is applied to auricular regions innervated by the auricular branch of the vagus nerve. Because of its low-risk profile, non-surgical application, and potential autonomic regulatory effects, taVNS has attracted increasing interest in autonomic physiology and cardiovascular research.

Previous studies in healthy individuals suggest that taVNS may influence autonomic balance, particularly through changes in heart rate variability (HRV), heart rate, and related physiological parameters. However, substantial heterogeneity remains across published taVNS studies with regard to stimulation parameters such as frequency, pulse width, current intensity, and intervention duration. Among these parameters, stimulation duration is one of the least standardized, and sham-controlled comparisons of different application durations remain limited.

This study is designed to investigate whether the acute autonomic effects of taVNS differ according to stimulation duration. The study uses a randomized, participant-blinded, sham-controlled mixed design. Healthy adults aged 18 to 40 years will be randomized to either an active taVNS group or a sham stimulation group. Participants will remain in their assigned group throughout the study. Within each group, each participant will attend three separate visits and receive stimulation for 5, 10, and 15 minutes in randomized order. Visits will be separated by 48- to 72-hour washout intervals.

Active taVNS will be applied bilaterally to the cymba conchae region using non-invasive stimulation parameters consistent with the study protocol. Sham stimulation will be delivered under visually and procedurally similar conditions to minimize expectancy effects. Before and immediately after each intervention session, autonomic and physiological outcomes will be assessed, including heart rate variability derived from RR interval recordings, heart rate, systolic and diastolic blood pressure, respiratory rate, and subjective discomfort measured by a visual analog scale.

The primary objective is to compare the acute autonomic responses to active taVNS and sham stimulation across different stimulation durations. The study also aims to explore whether a duration-response relationship exists for autonomic outcomes in healthy adults. Findings from this trial may help inform duration selection in future experimental and clinical taVNS research.

Study Type

Interventional

Enrollment (Estimated)

44

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Sefa Haktan Hatık Assistant professor, PhD
  • Phone Number: +90 368 271 55 28
  • Email: haktanhtk@gmail.com

Study Locations

  • Turkey (Türkiye)
      • Artvin, Turkey (Türkiye)
        • Artvin Coruh University, Artvin Vocational School, Disabled Care and Rehabilitation Laboratory
        • Sub-Investigator:
          • Ömer Dicle Kızıl, MSc
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

Healthy adults aged 18 to 40 years No known chronic systemic disease Non-smoker No regular medication use, including medications that may affect autonomic or cardiovascular function Able to understand the study procedures and provide written informed consent Willing to comply with study instructions and restrictions related to caffeine, alcohol, and strenuous exercise

Exclusion Criteria:

Any known chronic systemic disease Current smoker Regular medication use, including medications that may affect autonomic or cardiovascular function Inability to understand the study procedures or provide written informed consent Unwillingness or inability to comply with study instructions and restrictions related to caffeine, alcohol, and strenuous exercise

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Active taVNS
Participants assigned to this arm will receive active transcutaneous auricular vagus nerve stimulation during three separate study visits. Stimulation will be applied for 5, 10, and 15 minutes in randomized order, with 48- to 72-hour washout intervals between visits.
Device: Active taVNS
Active transcutaneous auricular vagus nerve stimulation will be applied bilaterally to the cymba conchae region. Stimulation frequency will be 25 Hz, pulse width 200 to 300 microseconds, and intensity will be individually adjusted to a clearly perceptible but comfortable level. Depending on the study visit, stimulation will be delivered for 5, 10, or 15 minutes.
Sham Comparator: Sham stimulation
Participants assigned to this arm will receive sham stimulation during three separate study visits. Sham stimulation will be applied for 5, 10, and 15 minutes in randomized order, with 48- to 72-hour washout intervals between visits.
Device: Sham stimulation
Sham stimulation will be delivered using the same device under visually similar conditions. The sham procedure will be applied at a non-vagal auricular site or with minimal non-therapeutic stimulation, depending on the study protocol, for 5, 10, or 15 minutes according to the study visit.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in RMSSD
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in the root mean square of successive differences (RMSSD), derived from RR interval recordings, from pre-intervention (T0) to post-intervention (T1) after active taVNS or sham stimulation at 5, 10, and 15 minutes.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in high-frequency heart rate variability (HF-HRV)
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in high-frequency heart rate variability (HF-HRV) from pre-intervention (T0) to post-intervention (T1) after active taVNS or sham stimulation at 5, 10, and 15 minutes.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in heart rate
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in heart rate from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in systolic blood pressure
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in systolic blood pressure from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in diastolic blood pressure
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in diastolic blood pressure from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in respiratory rate
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in respiratory rate from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in subjective discomfort assessed by visual analog scale (VAS)
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in subjective discomfort assessed by visual analog scale (VAS) from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in SDNN
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in the standard deviation of normal-to-normal intervals (SDNN) from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in LF/HF ratio
Time Frame: [Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]
Change in the low-frequency/high-frequency ratio (LF/HF ratio) from pre-intervention to post-intervention after active taVNS or sham stimulation at each study visit.
[Time Frame: Baseline (pre-intervention) and immediately after intervention, at each study visit (5, 10, and 15 minutes)]

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sinop University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

  • Frangos E, Ellrich J, Komisaruk BR. Non-invasive access to the vagus nerve central projections via electrical stimulation of the external ear. Brain Stimulation. 2015;8(3):624-636. doi:10.1016/j.brs.2014.11.018
  • Farmer AD, Strzelczyk A, Finisguerra A, et al. International consensus based review and recommendations for minimum reporting standards in transcutaneous vagus nerve stimulation research. Front Hum Neurosci. 2021;14:568051. doi:10.3389/fnhum.2020.568051
  • Clancy JA, Mary DASG, Witte KKA, Greenwood JP, Deuchars SA, Deuchars J. Non-invasive vagus nerve stimulation in healthy humans reduces sympathetic nerve activity. Brain Stimulation. 2014;7(6):871-877. doi:10.1016/j.brs.2014.07.031

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

May 1, 2026

Primary Completion (Estimated)

August 31, 2026

Study Completion (Estimated)

September 15, 2026

Study Registration Dates

First Submitted

April 6, 2026

First Submitted That Met QC Criteria

April 13, 2026

First Posted (Actual)

April 15, 2026

Study Record Updates

Last Update Posted (Actual)

April 15, 2026

Last Update Submitted That Met QC Criteria

April 13, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • TAVNS5

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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