You’ve heard of the fight or flight response. Maybe even the fight-flight-freeze response. But you’ve never heard it explained like this! Polyvagal theory was originally proposed by Dr. Stephen Porges, a researcher, professor, and the founding director of the Traumatic Stress Research Consortium. His polyvagal theory speaks to the physical and psychological reactions that occur when the body perceives threat or is under stress.

This article aims to break down the three principles of polyvagal theory, address how the stress response can impact appetite and digestion, and provide examples of skills one can use to regulate the nervous system.

What is Polyvagal Theory?

Dr. Porges describes polyvagal theory as “The connection between the body and mind and our reaction to the external world around us.” The theory suggests that our nervous system responds to different stress and safety cues which ultimately impact our perceptions, emotions, behaviors, and body systems. 

He goes on to say “All living things have a nervous system that reacts to threat or safety, however humans have ability to change the reaction.” Dr. Porges suggests that by choosing to activate pathways that the body knows mean safety, we can effectively calm the nervous system.

The Hierarchy Ladder

The first principle of polyvagal theory, referred to as the “hierarchy,” describes the three main states of the nervous system. This is often illustrated as a ladder that can be traveled up and down through the different states. Ventral vagal occupies the top spot of the ladder, sympathetic the middle, and dorsal vagal the bottom.

We can also experience a mix of these states in both a safe and unsafe way. For the purpose of our discussion today, we are going to focus on the stress response and how these states manifest when we feel unsafe. For more information on the hybrid states, you can visit the Polyvagal Institute’s website.

Ventral Vagal State

This state refers to our nervous system when it is feeling calm and relaxed. We have feelings of safety, trust, and social connectedness. It is associated with positive social interactions, emotional regulation, willingness to take risks, and resilience to stress. In this state we play, love, laugh, and feel comfortable and happy.

Sympathetic State

The sympathetic state refers to our sympathetic nervous system which becomes mobilized when we sense danger or threat. Here we see the fight or flight reaction take place as the body and mind problem solve a way out of the unsafe situation.

However, the “unsafe situations” of the 21st century look a lot less like dealing with a saber-tooth tiger and more like taking a final exam, handling a difficult customer interaction at work, or getting into an argument online.

The brain still perceives stress and tells the body to have a physical reaction. This includes dumping adrenaline into the bloodstream, increasing heart rate and blood pressure, and directing blood flow to the muscles of the arms and legs for the quick get-away or fight that never ensues.

Dorsal Vagal State

The dorsal vagal state describes the nervous system when it is immobilized. This is the freeze response. One may feel depressed, hopeless, numb, or shut down. This pathway is the body’s last resort and occurs when the sympathetic response was unable to secure protection or solve the problem. We can only exist in the sympathetic state for a short time before dropping down the ladder to dorsal. Here we feel disconnected from ourselves and others.

Traveling the Ladder

We all travel up and down this ladder naturally throughout the day, sometimes without even realizing it! However trouble can ensue when our “home base” is in sympathetic or dorsal vagal. As you can imagine, when a person is chronically in one or both of these states, they are in constant states of stress and depression. This person may need to take purposeful care and action in order to climb back to the top of the ladder (ventral vagal) to resume feelings of safety and connection. More on this in the next section.


Now that you know the range of states the nervous system can occupy, let’s explore the second principle of polyvagal theory: neuroception.

The Autonomic Nervous System

The autonomic nervous system (ANS) acts as a surveillance system to scan your body, environment, and even other people’s nervous systems, to determine safety or threat.

The ANS does this subconsciously but its ability to correctly detect safety or threat is dependent on its learned history. Someone with a trauma history or who is chronically exposed to stress may have a harder time detecting safety and may have less resilience to future stress.

In these situations, the ANS is always on the lookout for danger and can even mistake safety for threat. Instead of focusing on regulating the systems that keep us happy and healthy, it is constantly activating the sympathetic state.

As a result, this can mean a person rarely feels safe or connected. They may turn to dangerous coping strategies such as substance abuse or an eating disorder to find relief. Many unexplainable physical symptoms such as digestive issues, autoimmune diseases, chronic fatigue and pain, or migraines can occur. Mental health conditions such as anxiety, depression, attention deficit, and isolation are also common.

The research conducted by Dr. Porges has led to many developments in how to retrain an ANS to be more resilient to stress and accurately detect and interpret signals of safety and danger. This work is often done with the help of a medical or mental health professional that understands polyvagal theory. There are also practices you can do on your own, some of which are listed later on in this article.


The third and final principle of polyvagal theory is co-regulation. We all desire to feel connected to others socially and when we connect with others in a positive way, we feel calm and safe. The action of co-regulation starts the moment we are born. A baby is born with the ability to cry in order to be cared for. When the baby cries and is then picked up and soothed, it starts to calm.

Our nervous systems look for and need others with whom we feel safe enough to connect and with whom we can create supportive and protective relationships.

The Social Engagement System

Dr. Porges refers to something called the ‘social engagement system’ which is the way we interact with others. We send out messages to others with our nervous system via our facial expressions, body language and voice tone. These messages convey if we are welcoming to that person or not. We also receive and interpret signals from others in order to decide how we feel about them and how to proceed.

One of the best ways to retrain the nervous system is through co-regulation. Spending time with others who have a regulated nervous system, feel safe, and give us signals of calmness and happiness can help us feel the same.

Appetite and Digestion

In order to see how the stress response affects digestion, we have to first talk about the vagus nerve. The vagus nerve is the longest cranial nerve in the body, stretching from the brainstem down to the stomach. It is often referred to as the “mind-body connection.”

When a threat is perceived, the vagus nerve tells the brain to direct blood away from the digestive system (and a number of other organs) which can result in physical symptoms for some people. This might look like decreased appetite; slowed motility in the stomach & small intestine resulting in constipation, stomach pain, or heartburn; decreased absorption of nutrients; decreased secretion of digestive enzymes resulting in nausea or unintentional vomiting; premature fullness and bloating; and increased motility in the large intestine resulting in bowel urgency.

For example, think about a time when you were about to speak or perform in front of a crowd. Did you feel butterflies in your stomach? Nausea? Decreased appetite? Did you experience constipation leading up to the day and diarrhea the day of?

Is it any wonder that we don’t feel like eating when we are stressed or anxious? Eating in and of itself can cause anxiety for those with disordered eating. One way to support healthy digestion is to practice regulating the nervous system.

Regulating Your Nervous System

There are many different ways to calm the nervous system (sometimes called grounding or anchoring oneself). No one skill works for everyone and often it helps to have multiple skills in one’s toolbox.

Assessing and Meeting Your Needs 

The first step to calming your nervous system is to assess the possible reason(s) you are feeling mobilized and what you need to climb the ladder back to safety and calm feelings. You might assess that you feel lonely and desire connection. Maybe you feel overwhelmed and assess you need quiet time or comfort. Perhaps you feel angry and assess you need to move your body or find a distraction. Whatever the need is, you can choose to engage in practices to meet the need in a supportive way.

Regulation Techniques

The following is a list of techniques and skills for regulating (this is not a complete list):

Self-regulation by activating the vagus nerve:

Co-regulation by interacting with a trusted person with whom you have a positive social connection:

  • Calling or talking together  
  • Watching a movie together
  • Eating a meal together
  • Hugging, cuddling or gentle touch
  • Group activities

Seek professional support from someone who is familiar with polyvagal theory if you are struggling with anxiety, depression, trauma, or other mental health issues. They can help you understand and manage your ANS responses to stressors.

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It’s important to remember that achieving a ventral vagal state can take practice and patience. Experiment with different techniques and find what works best for you.

If you would like to talk to a dietitian or nutritionist about addressing GI symptoms that you think are related to stress, please contact us »