The body is packed with nerves, all of which perform different jobs and roles. The vagus nerve runs throughout the entire body and contributes to many functions, including mood regulation and digestion.
As a main part of the parasympathetic nervous system, the vagus nerve can also play a role in the fight-or-flight response, trauma and trauma recovery.
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What Is the Vagus Nerve?
The vagus nerve is the longest in the autonomic nervous system. It runs from the brainstem through the neck and abdomen, carrying signals and bringing information between the brain, digestive system, lungs, and other organs.[1] It has several vital functions that support your nervous system and overall health, such as the gag reflex, slowing heart rate, heat regulation, and controlling blood pressure levels.
However, the vagus nerve is also involved in mental health and well-being through its nerve fibres and branching pathways. Traumatic experiences can contribute to an overactive vagal response in the vagus nerve, leading many patients to experience anxiety, mood changes, nausea, and pain.
High levels of stress and anxiety can also trigger the vagus nerve.[2] When overstimulated, it can affect the gut and body, causing symptoms such as vomiting, dizziness, and abdominal pain. However, it is possible to soothe and relax the vagus nerve through gentle nerve stimulation techniques, such as breathing exercises that slow the heart rate and relax the body.
Polyvagal Theory & Functions of the Vagus Nerve and Its Nerve Branches
The vagus nerve plays a central role in regulating the body’s internal state. It acts as a two-way communication highway between the brain and the body, helping us respond to our environment and manage stress.
The ventral vagal pathway supports social engagement, calmness, facial expression, and the ability to feel safe while connecting with others. When this pathway is active, people are more likely to feel grounded, emotionally regulated, and present.
The dorsal vagal pathway supports immobilisation and energy conservation. In moments of extreme threat, it can slow heart rate, reduce metabolic activity, and contribute to feelings of shutdown or numbness. While protective in acute danger, prolonged activation can make people feel disconnected or low in energy.
Polyvagal Theory, developed by Dr. Stephen Porges, explains how the nervous system responds to safety and threat cues via these pathways. Central to the theory is neuroception, the nervous system’s automatic detection of risk or safety in the environment. Through neuroception, the ventral vagus responds to safety cues, while the dorsal vagus responds to threat cues.
According to Polyvagal Theory, the nervous system has three primary ways to respond:
Social engagement system – regulated by the ventral vagus, this system allows connection, communication, and co-regulation with others.
Sympathetic nervous system – the classic fight-or-flight response, preparing the body to confront or escape danger.
Dorsal vagal immobilisation – the freeze or shutdown response, which can occur during overwhelming threat or trauma.
These systems are fluid. Over the course of a day, people may move from social engagement while talking with a loved one, to mobilisation in a stressful meeting, to moments of shutdown when overwhelmed. Understanding these patterns can help individuals recognise their own nervous system responses and work toward greater regulation and connection.
The Lasting Impact of Trauma
When the nervous system is overwhelmed by trauma, it can be difficult for people to move back to a state of safety as they are constantly on high alert for danger. This can contribute to an overactive vagus nerve and cause physical trauma symptoms such as unexplained pain and nausea.
As the dorsal side of the vagus nerve is on high alert for danger, those who have experienced past trauma can jump immediately into the freeze or immobilisation response. They may associate more social cues, such as a change in tone of voice or body language, as dangerous and freeze to protect themselves from further harm.
Polyvagal Theory suggests that the ventral side of the vagus nerve should be stimulated to move trauma survivors out of the freeze response and into the social engagement system.
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Common Symptoms of Vagus Nerve Dysregulation
When autonomic regulation is disrupted, people may notice patterns such as digestive discomfort, shallow breathing, fatigue, fluctuations in heart rate, or increased muscle tension. Emotionally, this can present as anxiety, irritability, emotional numbness, or difficulty identifying feelings.
Socially, individuals may experience difficulty feeling connected, changes in vocal tone, withdrawal from relationships, or heightened sensitivity to perceived rejection. These patterns reflect shifts in nervous system regulation rather than structural damage to the vagus nerve itself.
It is important to recognise that these experiences exist on a spectrum. They are not diagnostic on their own but can indicate that the autonomic nervous system is working hard to manage stress.
What Triggers the Vagus Nerve?
The vagus nerve responds to cues of safety and danger through neuroception. Triggers can include obvious stressors such as conflict, illness, or traumatic reminders. They can also include subtle cues such as a change in tone of voice, body posture, facial expression, or an unexpected touch.
Internal triggers are just as important. Fatigue, hunger, hormonal changes, chronic stress, or sensory overload can lower the nervous system’s capacity to regulate. When the system perceives overwhelm without adequate support, the dorsal vagal pathway may become dominant, leading to shutdown or freeze.
Because neuroception operates below conscious awareness, people are often unaware of what has triggered a shift in state. They may simply notice that their mood, energy, or connection changes suddenly.
Causes of Vagus Nerve Dysfunction
Vagus nerve dysfunction is rarely caused by a single factor. It often develops through prolonged stress, trauma, or repeated experiences of overwhelm. Early life adversity, attachment disruption, medical trauma, or chronic relational stress can shape how the nervous system responds over time.
When the body repeatedly experiences situations that feel unsafe or inescapable, the dorsal vagal response can become a habitual pattern. What began as an adaptive survival response may persist even when current conditions are no longer threatening.
Chronic stress without adequate recovery can also contribute to dysregulation. When the nervous system does not have consistent access to safety, connection, and rest, it may struggle to return to balance. Understanding these patterns through a trauma-informed lens allows people to approach symptoms with curiosity rather than self-criticism.
Working With the Vagus Nerve
When people feel safe, they operate from within their social engagement system and connect with the world around them. There are several ways to work with the ventral side of the vagus nerve and introduce feelings of safety:
- Explore triggers – triggers are often formed in response to a traumatic event. For example, someone physically assaulted may react strongly if a person accidentally bumps into them. Awareness of individual triggers can help inform how people respond to them and identify ways to move back into the social engagement state.
- Bring awareness to the body – trauma can affect people’s relationships with their body, contributing to symptoms such as dissociation and hyperarousal. Focusing on the body by using meditation techniques and interventions, such as somatic experiencing, can help people become aware of their reactions and provide them with the tools to work through the fight, flight and freeze responses.
- Foster healthy relationships – traumatic events can be incredibly isolating, and many people struggle to express their feelings or talk about their experiences. Supportive relationships, where people feel safe and comfortable, activate the social engagement system and create connections.
- Practice breathing exercises – the vagus nerve is heavily involved in the parasympathetic nervous system, which promotes calmness and relaxation. As the vagus nerve communicates with the diaphragm, deep breathing stimulates the parasympathetic nervous system, which helps move the body into a more relaxed state.
The vagus nerve is incredibly powerful and informs many bodily functions. It relays messages of both danger and safety around the body and, in trauma survivors, contributes to elevated feelings of danger. Working with the vagus nerve offers people a way to build regulation and resilience after trauma supporting long-term nervous system health and therapeutic care.
When to Seek Support For Vagus Nerve
It may be helpful to seek professional support if symptoms of shutdown, anxiety, digestive distress, or emotional disconnection persist despite self regulation efforts. If daily functioning, relationships, or work are being impacted, additional guidance can provide structure and safety.
Trauma informed therapy can support nervous system regulation by helping individuals identify triggers, build regulation skills, and gradually restore a sense of safety in the body. Support is not about fixing something broken, but about creating the conditions in which the nervous system can recalibrate.
If symptoms feel overwhelming or difficult to manage alone, reaching out for professional guidance can be an important and empowering step toward recovery.
If you have a client or know of someone struggling with anything you have read in this blog, reach out to us at Khiron Clinics. We believe that we can improve therapeutic outcomes and avoid misdiagnosis by providing an effective residential program and outpatient therapies addressing underlying psychological trauma. Allow us to help you find the path to realistic, long-lasting recovery. For more information, call us today. UK: 020 3811 2575 (24 hours). USA: (866) 801 6184 (24 hours).
FAQs
Can emotional trauma damage the vagus nerve?
There is no strong scientific evidence that emotional trauma physically damages the vagus nerve itself. However, trauma can affect how the autonomic nervous system functions. This may alter patterns of vagal regulation, influencing heart rate variability, digestion, stress responses, and emotional regulation. In other words, trauma is more likely to affect how the nervous system operates rather than structurally injure the nerve.
What happens when the vagus nerve is triggered?
The vagus nerve is continuously active as part of normal autonomic functioning. When parasympathetic activity increases, it can slow the heart rate, influence digestion, and promote a state of physiological calm. In some situations, strong vagal activation can lead to lightheadedness, nausea, or fainting, such as in vasovagal syncope. The experience depends on context and the balance between sympathetic and parasympathetic activity within the broader nervous system.
How do you know if you have a vagus nerve problem?
True vagus nerve dysfunction is relatively rare and is usually identified in medical settings, often following injury, surgery, or neurological illness. Symptoms might include difficulty swallowing, voice changes, abnormal heart rate regulation, or digestive issues. More commonly, people experience stress-related symptoms linked to broader autonomic dysregulation rather than a specific vagus nerve disorder. If symptoms are persistent or concerning, medical assessment is important.
What causes the vagus nerve to become overactive?
In medical contexts, excessive vagal activation can occur in response to pain, fear, dehydration, prolonged standing, or intense emotional reactions, sometimes resulting in fainting. In psychological discussions, the term “overactive vagal response” is often used more loosely to describe parasympathetic dominance or shutdown patterns. However, this language reflects functional nervous system shifts rather than confirmed nerve pathology.
How long does a vagus nerve episode last?
Episodes such as vasovagal fainting typically resolve within minutes once a person is lying down and blood flow to the brain is restored. Stress-related autonomic shifts may last longer, depending on context, perceived safety, and individual regulation capacity. Chronic patterns of dysregulation are less about single “episodes” and more about ongoing nervous system conditioning, which can improve gradually with regulation practices and appropriate support.
Sources:
[1] Goggins E, Mitani S, Tanaka S. Clinical perspectives on vagus nerve stimulation: present and future. Clinical Science. 2022;136(9):695-709. doi:10.1042/CS20210507
[2] Kenny BJ, Bordoni B. Neuroanatomy, Cranial Nerve 10 (Vagus Nerve) [Updated 2021 Nov 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537171/
