A cable that mostly listens
If the vagus nerve had a job title, "messenger" would fit better than "commander." It runs from the brainstem down through the neck into the chest and gut, and most of what travels along it is the body reporting upward — not the brain issuing instructions downward (1,4). Your brain doesn't have to ask how your heart is doing. It already knows, because the vagus nerve never stops telling it.
That's what makes it an interesting target. Add a small, controlled signal into that same channel, and you're not overriding the body's instructions — you're changing part of the conversation the body is already having with itself.
Cervical vs. auricular: why the route matters
Non-invasive stimulation can reach the vagus nerve in two places: near the ear, or at the neck. Nervelo uses the neck — the cervical route. This isn't a minor detail. The research field treats cervical and auricular stimulation as genuinely different areas of study; a finding from an ear study doesn't automatically transfer to the neck, or the other way around (5). Everything below is filtered to cervical-route research specifically, so what you're reading actually matches how Nervelo works — not a nearby but different technology.
The evidence
What cervical stimulation has measured so far
Focus & cognitive performance — the strongest cervical evidence base
ctVNS improves cognitive performance under sleep deprivation
- 40 participants, 34 hours of sustained wakefulness
- Better arousal and multitasking vs. control
tcVNS improves sensory performance in humans
- Improved auditory and visual performance
- Measurable HRV changes alongside performance gains
tcVNS enhances vocabulary acquisition, mitigates fatigue
- Conducted at a US Dept. of Defense language school
- Faster learning + anti-fatigue and pro-focus effects
Cognitive function and brain activation before/after tcVNS
- Improved cognitive function in healthy adults
- Confirmed with direct brain activation imaging, not just self-report
Recovery & heart rate variability (HRV)
tVNS HRV crossover trial — 10Hz/25Hz cervical protocols
- Significant increase in SDNN (the standard HRV marker) vs. sham
- 10Hz/250µs protocol showed the strongest effect
tcVNS activates the cholinergic anti-inflammatory pathway
- Links cervical vagal signaling to inflammatory regulation
- Relevant to recovery and autonomic balance
Stress & autonomic nervous system
tcVNS reduces sympathetic responses to stress
- Reduced sympathetic arousal, heart rate, and vascular stress response
tcVNS alters brain activity during traumatic stress
- Increased activation in anterior cingulate cortex and hippocampus
- Regions linked to autonomic control
Neuromuscular excitability
tcVNS improves motor cortex excitability
- 28 healthy adults, effect measured after a single 30-minute session
Where sleep research stands today
We're not going to pretend every claim in this space is settled — but on sleep specifically, the story is more encouraging than we expected when we started digging. Most cervical research to date has clustered around stress, cognition, and HRV. Sleep-specific research is younger, but early results are surprisingly promising: one industry pilot tracking 40 people using cervical stimulation twice a day found sleep quality (measured by the PSQI, a standard sleep questionnaire) improved by 32% at two weeks and 41% by week four.
That's early-stage, company-run data without a sham-controlled comparison group — a promising signal, not definitive proof, and we think it's worth telling you plainly which one it is. The direction looks good. We'll keep this page updated as more independently reviewed, cervical-specific sleep research gets published.
References
- Thayer JF, Lane RD. A model of neurovisceral integration in emotion regulation and dysregulation. J Affect Disord. 2000;61(3):201–216. PubMed
- Porges SW. Cardiac vagal tone: a physiological index of stress. Neurosci Biobehav Rev. 1995;19(2):225–233. PubMed
- Thayer JF, Mather M, Koenig J. Stress and aging: A neurovisceral integration perspective. Psychophysiology. 2021;58(7):e13804. PubMed
- Prescott SL, Liberles SD. Internal senses of the vagus nerve. Neuron. 2022;110(4):579–599. PubMed
- Soltani D, Azizi B, Sima S, et al. A systematic review of the effects of transcutaneous auricular vagus nerve stimulation on baroreflex sensitivity and heart rate variability in healthy subjects. Clin Auton Res. 2023;33(2):165–189. PubMed
- McIntire LK, McKinley RA, Goodyear C, McIntire JP, Brown RD. Cervical transcutaneous vagal nerve stimulation improves human cognitive performance under sleep deprivation stress. Commun Biol. 2021;4(1):634.
- Jigo M, Carmel JB, Wang Q, Rodenkirch C. Transcutaneous cervical vagus nerve stimulation improves sensory performance in humans. Sci Rep. 2024;14(1):3975.
- Farmer AD, Strzelczyk A, Finisguerra A, et al. International consensus based review and recommendations for minimum reporting standards in research on transcutaneous vagus nerve stimulation. Front Hum Neurosci. 2021;14:568051. PubMed
Nervelo is a general wellness product intended to support relaxation, sleep, and focus. It is not a medical device and is not intended to diagnose, treat, cure, or prevent any disease or medical condition. The research summarized above relates to cervical tVNS technology as a category, not to clinical trials of the Nervelo device itself.