Why Sona Works
SONA uses gentle, non-invasive stimulation of the vagus nerve through the skin of the outer ear, a method known as transcutaneous auricular vagus nerve stimulation (taVNS).
The vagus nerve is a key component of the parasympathetic nervous system, forming a critical communication link between the brain and organs including the heart, lungs, and digestive tract.
By delivering precisely timed, low-level electrical pulses to the auricular branch of this nerve, SONA activates vagal afferent fibres that send signals up to the brainstem. This initiates a cascade of effects: peripherally, it increases parasympathetic tone via acetylcholine, helping counteract chronic sympathetic dominance and restoring healthier autonomic balance.
Centrally, it engages key neuromodulatory centres like the locus coeruleus and dorsal raphe, which release noradrenaline and serotonin, neurotransmitters that support cognitive flexibility, attention and neuroplasticity.
In this way, SONA strengthens the body's ability to shift into restorative states, while priming the brain for adaptive change.
Key Characteristics
Non‑invasive & safe
No surgery, no implants, no medication.
Fast acting
Measurable shifts in heart‑rate variability (HRV), testers describing it as “a full-body reset".
Fully adaptive
Onboard sensors read HRV and sync stimulation with respiratory cycle, so the dose always matches your current state and your individual physiology.
Mechanisms of Action
Signal transmission to brainstem centers
taVNS activates the vagus nerve, sending signals to the nucleus tractus solitarius (NTS) in the brainstem. This, in turn, influences key systems that regulate stress hormones (via the HPA axis), alertness and focus (via locus coeruleus activity), and parasympathetic output (via the dorsal vagal complex).
Autonomic rebalancing
With repeated use, taVNS shifts the autonomic nervous system toward vagal dominance. This is reflected in increased high-frequency heart rate variability (HF-HRV) and a reduced LF/HF ratio, markers of improved parasympathetic tone.
Anti‑inflammatory reflex
Stimulation of efferent vagal fibers prompts acetylcholine release, which suppresses pro-inflammatory cytokines like TNF-α and IL-6 via α7 nicotinic acetylcholine receptors (α7-nAChR).
Cortical plasticity & neurochemical modulation
Evidence from human EEG/fMRI studies shows increased gamma-band activity, enhanced GABAergic signaling, and LC–NE engagement, supporting cognitive flexibility, learning, and adaptive state transitions.
Use case 1
Stress & Autonomic Regulation
Four recent crossover or parallel‑arm studies converge on robust reductions in physiological and endocrine markers of stress:
Cuberos‑Paredes 2025
Design: 12‑subject single‑blind taVNS vs sham during Mental Arithmetic Stress Test
Key Findings: Cortisol rise during stress reduced by >50 %; HRV LF/HF suppressed; psoriasis case showed 40 % daytime cortisol reduction after 3‑month home use
Sanchez‑Perez 2023
Design: 19 healthy adults; four‑way crossover (taVNS, tcVNS, tMNS, sham)
Key Findings: taVNS shortened LVETI (↑ vagal tone) and raised PEP/LVET, indicating sympathetic withdrawal under cognitive & cold‑pressor stressors
Yoshida 2025
Design: 15 volunteers; randomised exercise stress test ± taVNS
Key Findings: Peak HR fell ~4 bpm at VO₂‑max; faster vagal re‑entry in recovery, negligible BP change, ideal for athletic use
Le Roy 2023
Design: 44‑person single vs triple‑session design
Key Findings: Three sessions/week increased HRV, cognitive throughput, and sleep efficiency; magnitude gated by baseline parasympathetic reserve
Implication for SONA: These findings support SONA’s adaptive approach. During periods of acute stress, its closed-loop algorithms prioritise suppression of the LF/HF ratio and normalisation of cortisol levels. Once the immediate load subsides, the system transitions into recovery mode, focusing on enhancing HRV and promoting parasympathetic restoration.
Use case 2
Sleep Architecture & Primary Insomnia
Four sham‑controlled RCTs (n ≈ 210 combined) establish taVNS as a non‑pharmacological option for chronic insomnia:
- Wu 2022 – 20 min, 2×/day for 4 weeks: Pittsburgh Sleep Quality Index (PSQI) fell 8 points (a 3 point drop is clinically significant); 73 % responders vs 27 % sham
- Zhang 2024 (JAMA Net Open) – 30 min, 5 days/week, 8 weeks: -8.2‑point PSQI vs -3.9 sham; benefits sustained 12 weeks post‑treatment
- Yeom 2025 – 30 min nightly, 6 weeks: -4.5 PSQI; +58 min total sleep; ISI & WHOQOL improved
- Jackowska 2022 – 4 h/day for 2 weeks in community sample: within‑group PSQI gains (-1.9) but no superiority to sham, likely ceiling and site‑specific effects
Implication for SONA: The evidence suggests that taVNS promotes deeper, more restorative sleep by increasing overnight parasympathetic activity, reducing nocturnal cortisol, and stabilising thalamo-cortical sleep spindle dynamics. These effects align closely with SONA’s stress-regulation mechanisms, reinforcing its potential as a drug-free intervention for improving sleep quality in high-functioning users.
Use case 3
Cognitive & Performance Enhancement
Laboratory paradigms show rapid gains in executive function, creative ideation, language acquisition, and mood recovery:
- Set‑shifting & cognitive flexibility – 32‑person crossover: 25 Hz taVNS cut task‑switch costs vs sham without HRV change
- Divergent thinking – 80 participants: +15 % fluency/originality after 25 Hz intermittent taVNS (GABA‑linked)
- Mandarin tone learning – sub‑threshold 25 Hz pulses paired with salient categories doubled acquisition rate; effect generalised to new voices
- Mood rebound after exertion – 90 min taVNS boosted positive affect by 9 % in recovery phase; larger effect in low‑mood baseline individuals
- Conflict‑triggered control (Simon task) – taVNS enhanced N2 ERP adaptation, implicating LC‑NE modulation
Implication for SONA: These results align with SONA’s Focus and Neuroplasticity modes, which deliver burst-timed stimulation during periods of cognitive effort or skill learning. By pairing stimulation with active mental tasks, SONA targets circuits involved in attention, flexibility, memory encoding, and mood regulation, amplifying performance gains in real time and reinforcing them through adaptive plasticity.
Use case 4
MindSpire & Partnered Research Pipeline
Our in‑house programme (MindSpire Labs) and academic collaborations extend taVNS into translational domains:
- Tragus‑based stress reduction pilot – 25 Hz, 200 µs: LF/HF down 64 %; α‑frontal EEG asymmetry shift toward relaxation in 5/5 subjects
- 30‑30 HRV biomarker study – feasibility of HRV decline as pre‑symptomatic COVID signal; validated by subsequent large datasets
- ReSONAnce Breathing Assessment (n = 51) – identified 5 bpm as population‑mode reSONAnce, now embedded in SONA’s breath‑sync protocol .
- TinnSpire (taVNS + sound) & Parkinson’s dual‑mode (taVNS+GVS) – multi‑session feasibility shows cumulative HRV gains and attentional improvements lasting up to 3 weeks
- Upcoming VR‑VNS for Pain, cognition in psychosis, epilepsy, FND, extreme‑environment resilience – multi‑centre grants in preparation
Safety & Tolerability
Across >300 participants in the cited RCTs and pilots, adverse events were mild, transient, and comparable to sham, typically brief ear prickling or vertigo resolving within minutes. No serious device‑related events or heart‑block episodes have been reported.
Key References
- Cuberos‑Paredes E et al., Physiol Reports 2025.
- Sanchez‑Perez JA et al., Front Neurosci 2023.
- Yoshida Y et al., Circ Reports 2025.
- Le Roy B et al., Front Neurol 2023.
- Wu Y et al., Brain Sci 2022.
- Zhang S et al., JAMA Net Open 2024.
- Yeom JW et al., Sleep Med 2025.
- Jackowska M et al., Auton Neurosci 2022.
- Borges U et al., Front Neurosci 2020.
- Colzato LS et al., Neuropsychologia 2018.
- Llanos F et al., NPJ Sci Learning 2020.
- Ferstl M et al., Psychol Med 2022.
- Fischer R et al., Cogn Affect Behav Neurosci 2018.
(Full bibliographic list and PDF links available upon request.)