The goal of this clinical trial is to evaluate whether the LasaiON program, which combines transcutaneous auricular vagus nerve stimulation (taVNS) with breathing supported by heart rate variability biofeedback (HRV-B; emWave), reduces emotional distress and improves stress-regulation processes in adults. The study will also assess the safety, tolerability, and feasibility of the intervention.
The main questions it aims to answer are:
1. Does the LasaiON program reduce emotional distress in adults? 2. What physiological, psychological, and verbal-cognitive changes are observed following the intervention? 3. What discomforts, adverse effects, or tolerability issues do participants experience during the program?
Researchers will use a prospective 2 × 2 factorial randomized controlled design to examine the effects of stimulation condition (active taVNS vs. sham taVNS) and training condition (active HRV-biofeedback vs. control training), as well as their potential interaction. Participants will be randomly allocated in equal proportions (1:1:1:1) to one of four groups: sham taVNS + control training, sham taVNS + HRV-biofeedback, active taVNS + control training, or active taVNS + HRV-biofeedback.
Participants will:
* undergo baseline assessments on Day 1 before the intervention; * complete 5 consecutive daily 60-minute sessions according to group allocation; * undergo post-intervention assessments on Day 5 after the final session; * complete psychometric, physiological, and verbal-cognitive assessments, including STAI, HAM-D, WHO-5, EEG, skin conductance, startle response, heart rate variability measures derived using Kubios HRV Premium, and daily five-word reports with valence ratings analyzed using IRaMuTeQ; * have adherence and tolerability recorded at each session using a checklist.
Ability to provide written informed consent
Physically healthy, with no relevant uncontrolled medical condition
Availability to complete the 5-day study protocol (1 session/day), including baseline and post-intervention assessments
Intact external ear and suitability for electrode placement on the tragus and acquisition of study recordings (EEG, EDA, HRV)
History of cardiovascular disease, diabetes, or hypertension
Severe bradycardia
Active implanted electronic device (e.g., pacemaker, cochlear implant, neurostimulator)
History of vagus nerve transection surgery (cervical vagotomy)
Factorial
LasaiON
Combination productParticipants will complete one 60-minute session per day. After verification of pre-session requirements, the researcher will place the EEG cap and the HRV, EDA, and EMG sensors and obtain baseline measures. Depending on allocation, participants will receive either active taVNS through stimulation electrodes placed on the auricular target area or sham taVNS using the same device setup without active therapeutic stimulation. From minutes 5-35, participants will remain seated while physiological activity is continuously recorded and they view segmented material from Our Oceans. From minutes 35-50, those allocated to active HRV-biofeedback will use the Coherence Coach platform to learn and practice slow breathing at 6 breaths/min, whereas control participants will observe their physiological activity on screen without guided breathing training. Each night at home, intrusive thoughts will be recorded through a brief Google Forms self-report and later analyzed with IRaMuTeQ.
State anxiety score
Change in state anxiety assessed with the State Anxiety subscale of the State-Trait Anxiety Inventory (STAI-State). Scores range from 20 to 80, with higher scores indicating greater anxiety.
Depressive symptom score
Change in depressive symptoms assessed with the 17-item Hamilton Depression Rating Scale (HAM-D). Scores range from 0 to 52, with higher scores indicating greater depressive symptom severity.
WHO-5 well-being score
Change in emotional well-being assessed with the World Health Organization-Five Well-Being Index (WHO-5). Raw scores range from 0 to 25, with higher scores indicating better emotional well-being.
Change in RMSSD
Change in heart rate variability assessed by the root mean square of successive differences (RMSSD) using Kubios HRV software. RMSSD reflects beat-to-beat variability in heart rate and is reported in milliseconds (ms). Higher values indicate greater vagally mediated heart rate variability, whereas lower values indicate lower vagally mediated heart rate variability.
Number of participants with adverse events
Number of participants who experience at least one adverse event during the 5-day intervention period. Adverse events will be recorded systematically at each session.
Procedure-related discomfort score
Procedure-related discomfort assessed using an ad hoc Likert scale ranging from 0 to 5, where 0 indicates no discomfort and 5 indicates very severe discomfort. Higher scores indicate greater procedure-related discomfort.
Number of participants who complete all intervention sessions
Number of participants who complete all planned LasaiON intervention sessions during the 5-day intervention period. Higher values indicate greater intervention completion.
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University of the Basque Country (UPV/EHU)
Lead sponsor
Parasym Ltd.
Collaborator
This trial is not recruiting at the moment. You can still explore other options:
