Stephen Porge’s Polyvagal Theory has gained substantial attention in the practice of trauma therapy. This theory provides a helpful framework for understanding the relationship between our autonomic nervous system (ANS) and our well-being. The insights provided by Polyvagal theory can be incorporated into our healing work to better understand, and be able to influence our trauma reactions. 

What is Polyvagal Theory?

Before Polyvagal Theory, we thought of the autonomic nervous system as having two parts: the sympathetic and the parasympathetic branches. In this traditional model, the sympathetic branch was responsible for the fight or flight response, while the parasympathetic branch was responsible for tamping down the nervous system, getting us ready to rest and digest. Polyvagal Theory expanded this understanding by introducing the concept of a hierarchical structure within the parasympathetic system which is directly related to the development, structure, and function of the vagus nerve.

The Vagus Nerve 

The vagus nerve is the main component of the parasympathetic nervous system. It is the 12th cranial nerve and is responsible for regulating a number of bodily functions including digestion, breathing, and heart rate. The vagus nerve runs from the brain to the large intestine, traveling through the neck, chest, and body. Stimulation of the vagal nerve produces a calming effect, slowing the heart rate and dropping blood pressure. A person with higher vagal tone is better able to manage stress, has improved mood regulation, and has enhanced cognitive function. 

The vagus nerve is further subdivided into dorsal and ventral components:

  • The dorsal vagus connects from the diaphragm upward and helps create healthy homeostasis. 
  • The ventral vagus connects from the diaphragm downward and promotes healthy digestion. 

Porges identified three distinct states of autonomic response:

  1. Ventral Vagal State (Safety and Connection): This state is governed by the ventral vagus and is associated with feelings of safety, calm, and social engagement. When in this state, individuals are open to connection, can process emotions effectively, and have access to their full range of cognitive and creative abilities.
  2. Sympathetic State (Fight or Flight): When a perceived threat arises, the sympathetic system activates, preparing the body for action. This state is marked by hyperarousal as evidenced by increased heart rate, rapid breathing, and heightened vigilance. 
  3. Dorsal Vagal State (Shutdown and Dissociation): In cases of extreme or prolonged threat, the dorsal vagus nerve dominates, leading to a state of immobilization or collapse. Often called “freeze,” this can manifest as feelings of numbness, disconnection, or even dissociation.

Neuroception

How does the vagus nerve know when to switch from one state to the other? This is accomplished through the process of neuroception. Neuroception is when the autonomic nervous system takes in information without involving the thinking parts of our brain. This part of our nervous system is constantly asking “Am I safe?” just outside the level of our awareness. Over the course of evolution, neuroception developed to help humans not have to pay conscious attention to warning signals inside the body, outside of the body and between people. For instance, we are no longer aware that a slight shift in the breeze might mean that a predator is lurking nearby. 

We see a neuroceptive mismatch when our internal state doesn’t match our environment. An inability to calm defense systems in a safe environment leads to a habitually hypervigilant, alarmed state. Conversely, an inability to activate defenses in a risk environment leads to an inadequate response– either dulled or unaware or high risk taking. 

Social Engagement System 

The social engagement system is a neurobiological network that is activated when a person feels safe and connected. It is formed through linkages between the vagus nerve, trigeminal nerve (which provides sensory input from and motor control of face), the facial nerve, the glossopharyngeal nerve (responsible for innervating the middle ear and neck), and the accessory nerve (responsible for neck and shoulder movement and larynx control). The social engagement system promotes calm and is activated through eye contact, facial expressions, vocalization and orienting of the body and face toward others. If the social engagement system is engaged, then the vagus nerve is activated; conversely, only when the vagus nerve is activated can the social engagement system be engaged. In this sense, connection with others is a neurobiological need in order to regulate the nervous system and heal from trauma. It’s so powerful that I truly believe that if I could only prescribe one thing to my clients, it would be social connection.  

Implications for Therapy

Polyvagal Theory has profound implications for therapeutic practice. By understanding how the autonomic nervous system operates, we can better attune to our physiological states and respond in ways that promote safety and connection. Here are some key takeaways:

  1. Prioritize Safety: It’s important to seek safe environments, like therapy with a well-trained trauma professional. Trauma reactions are when our sympathetic state is activated or when a dorsal vagal state is activated. Either one of these states signals that the environment is not safe and the nervous system must take action. 
  2. Recognize Autonomic States: Identifying your autonomic state can help with figuring out in-the-moment interventions. For instance, if you are in a sympathetic state, it may help to engage a ventral vagal state through social connection. 
  3. Leverage Co-Regulation: Co-regulation happens when we engage our social engagement system. The process of calming one another through presence, eye contact, nonverbal cues, and tone of voice is a powerful method to promote regulation of the nervous system. I’ve had clients ask “how do we co-regulate?” and my answer is typically a version of “we are doing it right now.” 
  4. Increase Vagal Tone: Therapy is useful in increasing vagal tone and widening a person’s window of tolerance to distress. The modulation accomplished by activating the social engagement system “exercises” the nervous system. As you co-regulate with a therapist, your nervous system learns to move towards safety and connection. Meditation, especially transcendental meditation, helps increase vagal tone by allowing for movement into ventral vagal states. 

Conclusion

Polyvagal theory offers a nuanced understanding of the mind-body connection, providing tools to foster deeper healing and connection. Using safe spaces and environments in order to practice movement from sympathetic and dorsal vagal states to a ventral vagal state helps “exercise” the nervous system and bring greater vagal tone, which in turn helps reduce trauma reactions over team. Polyvagal theory, then, is a helpful framework to incorporate into the healing of trauma.