The Vagus Nerve

The vagus nerve is the X (10th) cranial nerve and is sometimes referred to as the wandering nerve due to its numerous branches. It connects the brain to most vital organs and is one of the main drivers of the parasympathetic nervous system, otherwise known as ‘rest and digest.’

The vagus nerve is also crucial for managing stress responses in the body. Thus, vagus nerve stimulation has been studied for its potential benefits for alleviating stress-related symptoms, pain, sleep issues, and others. Ways to stimulate or even ‘reset’ your vagus nerve have also been trending on social media sites like TikTok.

We felt it was important to introduce our readers to the vagus nerve and discuss its science, anatomy, and function. I dug up my neuroanatomy notes and dove into the latest research to provide you with a comprehensive overview of the vagus nerve.

Anatomy and function

The 12 cranial nerves send impulses between the brain and the body. The vagus nerve is the longest cranial nerve, branching out to connect to most vital organs and modulate the parasympathetic responses. Efferent fibers carry motor signals from the central nervous system (CNS) to the organs, while afferent fibers carry sensory information from the organs back to the CNS.

The vagus nerve originates in the brainstem and travels down the neck, where it branches into the pharyngeal and laryngeal nerves. In the thorax, the vagus nerve branches into the posterior vagal and anterior vagal trunks. The left recurrent laryngeal nerve and the cardiac branches also arise in the thorax. Traveling down the abdomen, the vagus nerve branches into esophageal, gastric, and celiac branches.

The vagus nerve is also divided into the right and left vagus nerves, each traveling down a different side of the neck to reach the target organs like the heart, lungs, and digestive organs.

Each vagus nerve branch innervates a different organ:

Pharyngeal	Laryngeal	Cardiac	Bronchial	Esophageal	Gastric	Celiac
Motor innervation to the pharynx and soft palate muscles	Motor innervation of the larynx	Innervation of the heart	Innervation of the lungs	Innervation of the esophagus	Innervation of the stomach	Innervation of the pancreas, spleen, kidneys, adrenals, and the small intestine

Vagal nerve tone

The vagal nerve has a key role in maintaining the parasympathetic drive in the autonomic nervous system (ANS). The vagus nerve works bidirectionally: it sends impulses from the brain to the organs and receives sensory feedback from the organs about any modulations that are needed in order to regulate things like heart rate, breathing rate, or digestion. Think of it as a driver for internal adaptations to environmental demands.

For example, in a high-stress situation, your heart rate elevates, and your digestion slows down due to the signal sent by the sympathetic nervous system. After the ‘danger’ passes, your heart rate goes back to normal, and your digestion continues to run smoothly, all thanks to the feedback-signal loop of the vagus nerve. The higher the vagal tone, the quicker and more efficiently your body can calm down after stress, and this is considered beneficial for your health.

Low vagal tone is associated with increased sensitivity to stress. People with low vagal tone are also more likely to stay in the fight-or-flight mode longer and may experience anxiety, poor digestion, elevated heart rate, or increased inflammation. Overall, low vagal tone and poor adaptability may be associated with various conditions.

Here are some of the possible manifestations of low vagal tone:

• Increased emotional reactivity
• Poor attentional regulation
• Increased stress and anxiety
• Increased depressive symptoms
• Trouble falling and staying asleep
• Prolonged recovery from stressors
• Low heart rate variability (HRV)
• Chronic inflammation
• Impaired metabolic functions
• Bloating and digestive issues

Lifestyle strategies for supporting vagus nerve function

There are several suggested ways to increase vagal tone, most of which overlap with popular wellness and stress management practices: deep breathing exercises, mindfulness and meditation, exercise, and cold exposure. All of these have some evidence for reducing stress. However, clear studies of whether they increase vagal tone are lacking, and what works for some may not work for others. A more scientific and clinical way to increase vagal tone is vagal nerve stimulation.

Vagus nerve stimulation (VNS)

There are two types of VNS: invasive (iVNS) and transcutaneous (tVNS). Due to safety concerns, the left vagus nerve is more commonly used for stimulation.

Invasive VNS

The FDA has approved iVNS for drug-resistant epilepsy and treatment-resistant depression. However, due to risks during device implantation, it is generally reserved for severe, intervention-resistant cases. The approved vagus nerve stimulation is invasive and involves a surgical procedure during which electrodes are wound around the vagus fibers, and a pulse generator is implanted in the front of the chest. iVNS carries surgery-related risks like infection, complications, or device malfunction.

Transcutaneous (noninvasive) VNS

As an alternative, tVNS is a noninvasive vagus nerve stimulation option that uses surface electrodes in the ear or the neck, depending on the vagus nerve branch targeted. Noninvasive vagus nerve stimulators have been used in many studies but currently have no defined guidelines on the most effective location, frequency, current intensity, or duration to achieve therapeutic effects. This stimulation type is generally well tolerated but may cause side effects like tingling, redness, irritation around the stimulation site, nausea, dizziness, and others.

Type	Technique	FDA-approved	Used for	Side effects
iVNS	Surgical insertion of the device	Yes, for treatment-resistant cases	Drug-resistant epilepsy Treatment-resistant depression	Surgical complications, device malfunction
tVNS	Topical attachment of electrodes	No	Studied for improvement in: Sleep Pain reduction Mood Stress-related conditions Depression Tinnitus Cognitive function Inflammation	Tingling, redness, irritation around the stimulation site, nausea, dizziness

Potential benefits of VNS

Vagus nerve stimulation is used in clinical settings and is available through at-home wellness-targeted devices. However, its effectiveness and benefits are still being researched. I dug into the science behind its benefits for physical and mental health.

Sleep

The transition from the awake state to sleep involves a shift from sympathetic to parasympathetic dominance, partly mediated by the vagus nerve. The vagus nerve may also contribute to better sleep by reducing inflammation and cortisol levels, both of which can interfere with sleep quality.

A two-week study on 68 adults aged 18–75 applied tVNS on the left tragus of the ear or the left earlobe for the control group. Both groups received four hours of daily stimulation for two weeks. The results showed that tVNS significantly improved global sleep scores when comparing day 0 to day 13; however, the differences were not statistically significant between the groups.

A randomized, double-blind study on 30 individuals with diagnosed primary insomnia administered tVNS stimulation in the auricular concha area or to the periauricular area for the control group for 20 minutes twice a day for four weeks. The targeted treatment group showed significant improvements in the Pittsburgh Sleep Index Scale (PSQI) compared to the baseline and the control group. No statistical improvements were seen in the Hamilton Anxiety Scale (HAM-A) and Hamilton Depression Scale (HAMD).

Another single-blind, randomized, controlled trial on 100 individuals with insomnia living in high altitudes found that tVNS in the left ear tragus for 30 seconds five times a week for four weeks improved PSQI, Insomnia Severity Index Scale (ISI), and Generalized Anxiety Disorder-7 (GAD-7) scores. Shortened sleep latency and longer deep sleep were also seen in the treatment group.

The overall evidence suggests that tVNS may be useful in improving sleep and relieving insomnia symptoms. However, most studies found insignificant differences with different stimulator placements, and all of them used different protocols and durations, making it hard to draw conclusions. Despite the rationale that vagus nerve stimulation improves sleep and my personal struggles with insomnia, I believe there needs to be more research on specific placement, treatment protocols, and the safety of tVNS.

Pain, headaches, and migraines

Vagus nerve stimulation has also been investigated for reducing pain and relieving cluster headaches and migraines.

A randomized, cross-over, patient-blind trial on 32 individuals with systemic sclerosis found that administration of tVNS for four non-consecutive hours daily for four weeks to the conchae of the left ear significantly reduced pain.

Furthermore, one study on 22 healthy adults found that bilateral tVNS for 35 minutes using 2Hz/100Hz bursts on the auricular concha had inconsistent results, as for some participants, vagus nerve stimulation reduced the perception of pain, while for others, the perception of pain increased. Furthermore, there were no significant differences compared to the control groups, suggesting that the results are influenced by individual sensitivity to pain, response to intervention, and the methods used.

A 10-week prospective, open-label, randomized study on individuals with chronic cluster headaches found that using noninvasive VNS (same a tVNS) on the neck three times for 2 minutes twice a day as an adjuvant therapy to standard care significantly reduced the number of attacks per week.

An observational study on people with episodic or chronic migraines administered tVNS on each side of the neck for two minutes twice a day for two months. The results showed a significantly reduced perceived pain intensity and a clinically significant reduction in headache days per month.

Several studies have investigated the use of vagus nerve stimulation to reduce pain. While some showed promising results, many failed to show significant improvements. It seems that benefits and effectiveness are heavily influenced by individual pain sensitivity and reaction to VNS. Overall, while the field looks promising, more research is needed to define the stimulation protocols and study conditions. It is also difficult to draw conclusions on the effectiveness, as each individual rates and perceives pain differently.

Stress-related disorders

Although yet to be fully understood, stress-related psychiatric conditions have been linked to dysregulation in the hypothalamic pituitary adrenal axis (HPA). It is hypothesized that the vagus nerve may influence HPA and, thus, the neural circuits involved in stress-related conditions.

A double-blind study on 24 healthy individuals with a history of psychological trauma exposed the participants to stressors and, immediately after, applied tVNS on the left side of the neck for 120 seconds with a handheld device. The results showed decreased sympathetic response as measured by heart ejection period, skin conductance, and respiratory rate.

Another research study on 22 individuals with PTSD found that tVNS on the left neck area found activation in previously hypoactive brain regions when participants were exposed to personalized trauma scripts.

Despite vagus nerve stimulation being researched for its role in the HPA axis as a way to alleviate symptoms of stress-related conditions, the current evidence is too weak and heterogeneous to draw such a conclusion. In healthy individuals, tVNS may help alleviate stress responses, but it is not suitable to treat or manage serious mental health conditions, especially with at-home, non-clinical devices.

Depression

Cervically implanted VNS has been approved by the FDA as an adjunct therapy for treatment-resistant depression. Due to its invasive nature and the need for surgery, it is limited to severe cases and only for clinical practices. To mitigate the risks, tVNS has been studied as an alternative treatment for individuals with depression.

A study on 49 individuals with major depressive disorder (MDD) found that self-administered tVNS on the auricular concha area for one month resulted in significant changes in the brain regions responsible for emotional regulation. The changes were associated with significant improvements in the Hamilton Depression Scale (HAMD) when compared to placebo.

However, another study that used auricular tVNS on people with depression daily for two weeks saw significant improvement in the Beck Depression Inventory (BDI), but not HAMD.

The antidepressant actions of tVNS require more research due to inconsistent results. Efficacy and exact mechanisms need to be studied and defined for it to match the surgical VNS implant.

Vagus nerve reset

The vagus nerve has been getting a lot of attention on social media, with TikTok influencers sharing ways to stimulate or even ‘reset’ it to improve various aspects of life and well-being.

First of all, there is no such thing as a vagus or any other nerve reset. Your body and organs cannot and do not need to be reset, especially not with techniques seen on social media.

Second, while there is a lot of useful information online with people sharing their experiences and practices that improve their well-being, most of the health influencers do not have a background in medical or scientific fields. While some of the advice, like breathing exercises or yoga to improve your vagal tone, may help you increase relaxation, this is not a medical or scientific statement — it is the advice of a person who found it helpful, so take everything with a grain of salt.

I asked Paula Vaidelauskaitė, who has a degree in Clinical and Cognitive Neuroscience, to share her thoughts.

“The growing availability of at-home vagus nerve stimulation devices presents both opportunities and risks. Unlike implantable VNS systems, noninvasive devices offer a more accessible and lower-risk option, but their effectiveness and safety remain uncertain.

While some devices show promise in preliminary studies, most lack rigorous clinical validation required for medical-grade treatments. Consumers should be cautious about claims made by manufacturers and prioritize remedies with robust scientific backing.”

Bottom line

The vagus nerve is a key player in the parasympathetic nervous system. It modulates stress responses and the function of most vital functions: heart rate, breathing, and digestion, to name a few. Dysfunctions of the vagus nerve are associated with increased emotional reactivity and issues like poor digestion, which can be expected in high-stress situations.

Clinical and at-home vagus nerve stimulation devices are available, with potential benefits to alleviate numerous conditions. However, the evidence for most is still inconclusive. Practices like meditation and breathing exercises may help increase the activity of the parasympathetic nervous system and the vagus nerve; however, there is no direct evidence.

Being mindful and managing stress is crucial both for your mental and physical health, but there is no such thing as a vagus nerve reset as promoted on social media.