tVNS – non-invasive vagus stimulation

What is the vagus?

The vagus nerve—also known as the tenth cranial nerve—is an important part of the peripheral nervous system. The vagus is the longest nerve in the body, stretching from the brain to the organs in the abdominal cavity.

It belongs to the so-called autonomic (vegetative) nervous system, specifically the parasympathetic branch, which is responsible for rest, relaxation, and regeneration.

The main role of the vagus nerve is to provide communication between the brain and various organs of the body, including the heart, lungs, gastrointestinal tract, and internal organs. It plays a crucial role in regulating heart rate, breathing, digestion, and metabolism.

As part of the parasympathetic nervous system, the vagus nerve acts as the counterpart to the sympathetic nervous system, which is responsible for activating the body and preparing it for physical or emotional stress.

The vagus has a calming effect on the body, promoting relaxation, recovery, and balance within the autonomic nervous system.

It also plays an important role in regulating the immune system, inflammatory responses, and mood.

Stimulating the vagus nerve can produce therapeutic effects. For example, it can reduce inflammation and improve mood and overall well-being.

What is the autonomic (vegetative) nervous system?

The autonomic nervous system is the subconscious (not under voluntary control) part of the peripheral nervous system that regulates the functions of internal organs (for example the heart, lungs, and digestive system) and orchestrates interactions between various physiological systems (for example the immune and cardiovascular systems) as responses to external and internal stimuli.

It consists of two branches: the parasympathetic (rest and digest) and the sympathetic (fight or flight), which exert different and often opposing effects on organ function (including breathing rate, pupil dilation, saliva production, digestion, peristalsis, and sexual arousal).

Increased sympathetic activity or reduced parasympathetic activity can lead to dysfunctions that produce chronic physical, psychiatric, and neurological symptoms.

Vagus stimulation increases parasympathetic activity, thereby promoting optimal autonomic balance and restoring healthy neurophysiological function.

What is neuromodulation?

Neuromodulation is a technology that acts directly on nerves. Changing (i.e., modulating) nerve activity can be achieved with medications or electrical impulses. Medications can be delivered by implanted “pumps” to the required site. In contrast, transcutaneous vagus stimulation is risk-free.

Neuromodulation can change lives. The treatment affects the whole body and can influence almost any disease or symptom, from headaches to tremors, spinal cord injury to urinary incontinence. Given this broad therapeutic scope, professionals consider neuromodulation one of the most promising treatment approaches for the coming decade.

Today, neuromodulation is most commonly used for chronic pain management. However, there are many other applications, such as deep brain stimulation (DBS) for Parkinson's disease, sacral nerve stimulation for pelvic disorders and incontinence, and spinal cord stimulation for ischemic conditions (angina, peripheral arterial disease). There are even neuromodulation devices like cochlear implants that restore hearing in deaf patients.

The latest application is vagus stimulation delivered through the tragus (the small flap in front of the ear canal) — tVNS — which has already shown beneficial effects in atrial fibrillation, depression, anxiety, long-COVID, rheumatoid arthritis, and chronic fatigue. Because the technology is new, many other indications are still under investigation.

What is tVNS (vagus stimulation)?

Transcutaneous electrical vagus nerve stimulation (tVNS) stimulates the vagus nerve through the skin.

It is delivered via electrical impulses applied to the tragus, the front part of the outer ear.

This stimulation can modulate vagus nerve function and thereby restore optimal balance in the autonomic nervous system.

That has many positive effects on the body, such as regulating heart rate, reducing inflammation, and improving overall health.

What is Nurosym?

Nurosym is a therapeutic device designed for non-invasive vagus stimulation (neuromodulation) via the tragus.

The device's efficacy has already been validated in more than 30 published clinical studies, demonstrating the technology's effectiveness across a wide range of conditions.

Nurosym has been shown to improve heart rate variability (HRV), a metric of autonomic nervous system health.

Higher HRV is generally associated with better health, fitness, and even a healthier emotional baseline. Low HRV is linked to risk factors such as illness, mortality, and stress. Low HRV has been observed in patients with a variety of conditions, including chronic cardiovascular diseases and disorders associated with autonomic dysfunction.

Furthermore, by restoring autonomic tone, Nurosym downregulates unhealthy immune response mechanisms through activation of the cholinergic anti-inflammatory pathway (CAP). Stimulating the release of the neurotransmitter acetylcholine reduces the production of pro-inflammatory cytokines and helps restart healthy nitric oxide production.

This is particularly useful in diseases driven by systemic inflammation, excessive sympathetic responses, and related pathological immune reactions.

Which conditions have shown proven benefit from Nurosym?

long-COVID

Long-COVID or post-COVID refers to symptoms that persist for weeks or months after a COVID-19 infection. Currently, treatment options for persistent symptoms following COVID infection (for example fatigue, musculoskeletal pain, breathing difficulties) are very limited.
In a clinical trial, Nurosym successfully reduced long-COVID symptoms in patients whose symptoms had persisted for at least twelve weeks or longer. Patients were treated daily for ten consecutive days for 35 minutes per day, and their physical and psychological symptoms were assessed at five and ten days after treatment initiation and one week after the end of stimulation. Significant symptom reduction was observed after the ten-day treatment, and the effect persisted after the stimulation ended.
The study suggests that Nurosym tVNS is an effective therapeutic option for reducing persistent long-COVID symptoms.

atrial fibrillation

rheumatoid arthritis

pain and fibromyalgia

sleep disorders

chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is characterized by extreme fatigue accompanied by many other unpleasant symptoms (for example pain). It can be associated with post-exertional malaise, non-restorative sleep, muscle weakness, and neurocognitive impairment.

Diagnosis is not simple. Symptoms comprising CFS are sometimes attributed to depression, anxiety, insomnia, or other conditions that overlap with these symptoms. With an incorrect diagnosis, symptoms may be attributed to psychological causes rather than biological ones.

Recently, several studies have found physiological explanations, identifying inflammation-driven mitochondrial metabolic disturbances. Mitochondrial damage as well as oxidative and nitrosative stress may be potential sources of CFS symptoms. Progressive inflammation can impair the vagus nerve's sensing mechanisms, leading to excessive sympathetic activation. This is supported by the observation that chronic fatigue syndrome often develops after an infection.

Non-invasive neuromodulation targeting the vagus nerve has been shown to reduce inflammatory cytokines and increase heart rate variability. Furthermore, the Nurosym tVNS device has been shown to improve chronic fatigue, including mood and energy levels.

depression

Depression is a mood disorder characterized by a persistently low mood (sadness, irritability, a sense of emptiness) and/or loss of interest in activities, causing significant impairment in daily life. Depression is highly heterogeneous, with varying symptom manifestations and potential pathophysiological roots that may explain differences in symptom response to medications among patients.
A large body of literature supports the effect of vagus nerve stimulation in depression, particularly in treatment-resistant depression, as either an exclusive or adjunctive therapy.
Functional magnetic resonance imaging (fMRI) studies have shown that stimulating the left-ear vagal afferent with tVNS induces favorable brain changes relevant to combating depression, such as a marked decrease in the blood-oxygen-level-dependent (BOLD) signal in limbic structures or activation of the anterior insula. Some of these studies have linked brain network changes to clinical improvement in depression scores.
The efficacy of tVNS in reducing or treating depressive symptoms is supported by randomized, placebo-controlled clinical trials. Improvements have also been shown in other neuropsychiatric disorders such as anxiety, epilepsy, and insomnia.

You can buy the Nurosym device here. 

Tips for tVNS treatment

Sympathetic and parasympathetic functions cannot be activated at the same time! They work oppositely and have opposite effects. It's like a seesaw. If one side is up, the other must be down!

Therefore, using vagus stimulation in the middle of workplace stress, during a gym workout, in traffic jams, in any tense situation, or during a panic attack is pointless.

Perform stimulation when you are already ready to calm down and fall asleep. Treat yourself before going to bed and then don’t “disturb yourself” again afterwards!

I already mentioned that the sympathetic (defend-or-flee) system takes precedence over the parasympathetic. If you are under strong stress, you cannot instantly activate the parasympathetic nervous system by command.

Try to reduce stress using multiple methods at the same time. For example, relaxation techniques, meditation, yoga, and breathing exercises help reduce stress and increase parasympathetic activity.

Begin vagus stimulation when you have managed to get rid of acute stress and are ready to relax.

When should you stimulate?

• Personalized timing: The optimal timing of stimulation varies between individuals. For some, morning stimulation can help start the day energetically, while for others evening stimulation may aid relaxation and sleep preparation.
• Consistent routine: Perform tVNS regularly, preferably at the same time each day. Consistency improves treatment effectiveness and helps the body develop positive responses.

How long should a session last?

• Session duration: Optimal duration can vary, but research generally recommends daily stimulation of 15–30 minutes, up to a maximum of 60 minutes. Duration also depends on stimulation intensity and individual response. Some people are more "sensitive" and experience parasympathetic effects quickly. Others with stronger stress (high sympathetic activity) may take longer for the treatment to "break through."
• Gradual start: If you are new to tVNS, start with shorter 5–10 minute sessions and gradually increase as your body adapts. Mild dizziness or nausea may occur after the first sessions, but these are rare and typically resolve after a few treatments.

Stimulation intensity and frequency

• The pulse intensity should be high enough to be noticeable but must not cause discomfort or pain. Gradual increases in intensity can help find the optimal balance between comfort and effectiveness.
• Treatment frequency is important. Daily use is recommended in most cases, but in some cases a few sessions per week may suffice. Frequency should be tailored to individual goals and responses to treatment.

How long until you notice effects?

Perhaps you recall Géza Hofi's great cabaret sketch satirizing the Rákosi regime, where an official asked a pig breeder how many piglets a sow would have... Well, how could anyone possibly predict that in advance?

Similarly, predicting how long it will take to activate the parasympathetic system falls into the realm of fortune-telling.

I have had astonishing experiences, such as a single 5-minute treatment resolving long-standing double vision (for specialists: the ocular symptom of myasthenia gravis).
Another user reported no effect even after two weeks.

The truth likely lies somewhere between these extremes.

For mild or moderately severe, relatively recent problems, the required time may be shorter. But breaking through years of chronic stress certainly cannot be achieved with just 1–2 sessions. In such cases at least 30–60 days of treatment is often necessary, even if you follow the recommendations outlined above.

If chronic stress is accompanied by other symptoms such as chronic inflammation or autoimmune disease, the answer is even more difficult. In such cases, expecting an effect from tVNS alone is unrealistic. You need a multimodal approach, addressing nutrition, exercise, stress-reduction techniques, and possibly temporary medications. Combining multiple methods (multimodal approach) is more likely to help than any single method alone.

Medical studies for professionals

Long-COVID

• Natelson, B., Blate, M., & Soto, T. (2022). Transcutaneous vagus nerve stimulation in the treatment of long covid-chronic fatigue syndrome. medRxiv, 2022-11.
• Verbanck P, Clarinval A, Burton F, Corazza F, Nagant C, Cheron G. Transcutaneous Auricular Vagus Nerve Stimulation (tVNS) can Reverse the Manifestations of the Long-COVID Syndrome: A Pilot Study. Advances in Neurology and Neurosciences Research. 2021; Autonomic improvement
• Stavrakis et al. TREAT AF – Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation: A Randomised Clinical Trial. Stavrakis et al. Clinical Electrophysiology 2020
• Jackowska M, Koenig J, Vasendova V, Jandackova VK. A two-week course of transcutaneous vagal nerve stimulation improves global sleep: Findings from a randomised trial in community-dwelling adults. Auton Neurosci Basic Clin. 2022 Jul 1

Autonomic nervous system support

• Stavrakis et al. TREAT AF – Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation: A Randomised Clinical Trial. Stavrakis et al. Clinical Electrophysiology 2020
• Jackowska M, Koenig J, Vasendova V, Jandackova VK. A two-week course of transcutaneous vagal nerve stimulation improves global sleep: Findings from a randomised trial in community-dwelling adults. Auton Neurosci Basic Clin. 2022 Jul 1

Neuroplasticity

• Jandackova et al. The effect of long-term non-invasive vagus nerve stimulation on cognitive performance: results from a randomized placebo controlled trial. Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation 2023, 16(2), 6.
• Thakkar et al. The effect of non-invasive vagus nerve stimulation on memory recall in reading: A pilot study. Behavioural Brain Research, 2023, 438, 114164.
• Tonsager A. The Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Novel Language Learning. Texas Christian University Library, 2020
• Richardson Z. The Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Reading Comprehension. Texas Christian University Library 2020
• Thakkar et al. The effects of transcutaneous auricular vagus nerve stimulation on reading comprehension. Texas Christian University. 2020
• Noé et al. Feasibility, safety and efficiacy of transauricular vagus nerve stimulation in a cohort of patients with disorders of consciousness. Brain Stimulat. 2020;13(2):427–9.

Cardiovascular disease

• Stravakis et al. Neuromodulation of Inflammation to Treat Heart Failure With Preserved Ejection Fraction: A Pilot Randomized Clinical Trial. Journal of the American Heart Association 2022
• Stavrakis et al. TREAT AF – Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation: A Randomised Clinical Trial. Stavrakis et al. Clinical Electrophysiology 2020
• Jiang Y, Po SS, Amil F, Dasari TW. Non-invasive Low-level Tragus Stimulation in Cardiovascular Diseases. Arrhythmia Electrophysiol Rev. 2020 Jun 3;9(1):40–6.
• Dasari et al. Effects Of Low Level Tragus Stimulation On Inflammation In Acute Decompensated Heart Failure. Journal of Cardiac Failure, 2023 29(4), 660-661.
• Kharbanda et al. Insights Into the Effects of Low-Level Vagus Nerve Stimulation on Atrial Electrophysiology: Towards Patient-Tailored Cardiac Neuromodulation. JACC: Clinical Electrophysiology 2023, 9(9), 1843–1853. https://doi.org/10.1016/j.jacep.2023.05.011