What is the Vagus Nerve?
The vagus nerve is a primary carrier of information describing the state of the body to the brain, and transmitting information from the brain back to the body. It’s a feedback mechanism which is responsible for maintaining homeostasis for many of our vital organs and brain/body functions. Research over the past few decades shows that the vagus plays a key role in managing our levels of stress as well as our body’s inflammation; in this age of stress- and inflammation-related disease, it is perhaps the most important nerve in the body for us to be paying attention to.
What does the Vagus Nerve do?
MOOD
As a key component of the parasympathetic nervous system, the vagus modulates your body’s stress response. As a cranial nerve X, it originates in the brainstem and influences the limbic system, which is responsible for regulating emotions and mood.
FACIAL & VOICE EXPRESSIONS
Branches of the vagus influence your facial muscles and the tone of your voice, both of which act as signals to the world, letting others know how you are feeling (and if it’s safe to interact with you). The vagus nerve supports speech by controlling the vocal cords and coordinating with breathing. It helps regulate tone and phonation, working alongside other nerves involved in articulation.
BREATHING
The vagus nerve plays a key role in regulating the activity of the diaphragm, the primary mover of breath in the body. It sends signals from the brain to the diaphragm, facilitating its contraction and relaxation during breathing, and thereby modulating the respiratory rate and volume. This connection allows for precise control of respiratory movements, ensuring efficient gas exchange and oxygenation of the body. This fine-tuning mechanism ensures that the body receives an adequate supply of oxygen and maintains a balanced level of carbon dioxide.
HEART RATE & BLOOD PRESSURE
The vagus nerve plays a key role in regulating heart rate by releasing specific neurotransmitters that slow down the heart rate, promoting a state of relaxation.
IMMUNE FUNCTIONS & THE INFLAMMATORY REFLEX
The vagus plays an important role in regulating immune functions. Afferent vagal pathways transmit signals related to tissue damage and immune reactions to the brain stem. After central processing of these signals, activated efferent vagal pathways modulate inflammatory reactions by inhibiting the synthesis and secretion of pro-inflammatory cytokines by immune cells.
DIGESTION
The vagus nerve plays a key role in regulating digestion by connecting the brain to the enteric nervous system (ENS). While the ENS independently manages many digestive functions, the vagus nerve influences gut health by stimulating the release of digestive juices and hormones that enable you to digest food properly. It also helps move food through your digestive tract, so waste products are removed efficiently from your body.
The Anatomy of the Vagus Nerve
For those interested in a more detailed anatomical look at the vagus, this diagram shows the full scope of the vagus nerve, including its branches to various organs and body parts.
​The vagus nerve is actually two bilateral nerves that extend from different parts of the brainstem and then join together just above the chest cavity. They have different roles: the right branch controls the heart and lower organs like the stomach, intestines, kidney, and liver.​​​​​
The left branch is involved in speech, eye contact, facial expressions, and the ability to tune in to other people’s voices (in Polyvagal Theory terms, our ‘social engagement system’).​​​​​
All vagus nerve illustrations by Alexis Cruz, © 2025 Polyvagal Institute. For educational use only; all rights reserved.
Vagus Nerve Stimulation
We can stimulate the vagus nerve using natural means, such as breathing, playing, doing yoga, and more. View the image here for useful methods.
We can also stimulate the vagus nerve using "VNS devices" specifically engineered for that purpose.
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Vagus Nerve Stimulation Devices
VNS devices fall into 2 general categories, those which are surgically implanted (iVNS) and those which are non-invasive (nVNS); both methods use electrical impulses that are carried by the vagus to the brain.
iVNS devices are typically used to treat headaches, epilepsy, stroke recovery and depression.
nVNS may be used for the same conditions as well as generally reducing stress, improving mood, lowering blood pressure and heart rate, and reducing inflammation.
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Non-invasive VNS Options
Natural means of activating the vagus nerve are preferable in that they are usually free, or low cost, and can be integrated with one’s lifestyle on an ongoing basis. However, for those who wish to further enhance vagal activation and to explore the newest technological advancements in this field, PVI has curated a list of nVNS devices which are researched, safe, and available on the market. List coming soon, please check back.
The Superhighway of Homeostasis
Humans have 12 pairs of cranial nerves (nerves which connect the brain to different locations in the body), the vagus being the tenth, referred to as Cranial Nerve X. Its name comes from the Latin, meaning ‘wandering’, as the nerve meanders from the base of the brain all the way down to the gut. It’s a bi-directional superhighway, carrying sensory information from the body to the brain (afferent nerves) and motor information from the brain to the body (efferent nerves).
Our Parasympathetic Nervous System (PNS), which is sometimes described as our ‘rest and digest’ function (in contrast to our Sympathetic Nervous System, which is often described as our ‘fight or flight’ function), is mediated primarily by the vagus nerve. It helps us recover and relax after expending a lot of energy, and it helps us digest our food.
The vagus and ‘vagal tone’: When the body needs to mobilize, as in a state of stress, danger, or even play, the sympathetic nervous system kicks into action: muscle tone tenses, heart rate picks up, and your critical thinking is reduced as your body prepares for action. Once the need for action is over, the vagus nerve acts as an inhibitor and helps slow things down by calming the heart and restoring a relaxed state. This intricate interplay between the sympathetic and parasympathetic systems is crucial for overall well-being and is sometimes referred to as vagal efficiency, or ‘vagal tone.’ About 80% of the fibers of the vagus nerve are related to the transfer of sensory information from the body to the brain (afferent), while the remaining 20% of the fibers transmit motor signals from the brain to the body (efferent).
Polyvagal Theory proposes that the vagus nerve comprises two evolutionarily distinct branches that support different adaptive behavioral and physiological responses: the ventral vagal complex (VVC) and the dorsal vagal complex (DVC). The VVC, unique to mammals and originating in the nucleus ambiguus of the brainstem, plays a critical role in promoting social engagement, emotion regulation, and feelings of safety and connection. In contrast, the DVC, which arises from the dorsal motor nucleus of the vagus and is shared with more primitive vertebrates, is associated with immobilization responses—including shutdown or dissociation—that may occur under extreme threat. According to PVT, the autonomic nervous system is hierarchically organized, with the VVC as the most evolutionarily recent system that supports flexible, reciprocal social behavior. By understanding how these vagal circuits influence our physiological state, PVT offers insights into how the nervous system shapes behavior, emotions, and relational capacity, especially in response to cues of safety or danger.
In Polyvagal Theory, the social engagement system is linked to the ventral vagal complex (VVC), which regulates both the heart and the striated muscles of the face and head via its coordinated activity with other cranial nerves (V, VII, IX, X, XI). When an individual perceives cues of safety, the VVC becomes active, inhibiting defensive states, lowering heart rate, and enabling social behaviors such as facial expressiveness, vocal prosody, eye contact, and head orientation. This physiological state supports relaxation, creativity, emotional regulation, and the capacity to connect with others. However, when safety is disrupted—such as through trauma or chronic stress—the VVC may become inhibited, resulting in difficulty maintaining social engagement, diminished emotional regulation, and a compromised ability to signal and detect safety in relationships.
The auricular branch of the vagus nerve: The auricular branch of the vagus nerve, a sensory branch arising from the superior ganglion of the vagus, conveys somatosensory input from the external ear and ear canal to the brainstem. While not a motor component of the Social Engagement System, it may contribute sensory feedback that influences autonomic tone. This pathway has clinical relevance, as non-invasive stimulation of the auricular branch (e.g., taVNS) can modulate vagal activity and has shown potential in supporting emotional regulation and reducing stress responses.
The vagus nerve is actually two bilateral nerves that extend from different parts of the brainstem and then join together just above the chest cavity. They have different roles: the right branch is primarily involved in homeostatic, automatic processes such as regulating heart rate and digestion, while the left branch is involved in voluntary behaviors, such as vocal tone, facial expressions, and the ability to tune in to other people’s voices (in Polyvagal Theory terms, our ‘social engagement system’).
Questions about the Vagus Nerve?
Watch these Short Videos
Peter Staats, MD, researcher, President and Founder of The Vagus Nerve Society
answers some common questions about the vagus nerve in this series of short videos
