The Polyvagal Theory is a biological theory that explains our body's physiological responses to various situations. Essentially, it helps regulate our emotional states based on the context we find ourselves in, deciding whether we need to be calm and social, ready for action, or be in a shutdown mode.

This theory was developed by Dr. Stephen Porges in the 1990s. Porges was trying to understand why humans and mammals react to danger and safety in certain ways. He was studying the traditional concept of the "fight, flight, or freeze" response but believed that it didn't fully explain our body's diverse reactions.

Porges' son, who was frequently suffering from middle ear infections, unexpectedly provided the inspiration for the theory. Porges noticed a change in his son's facial expressions and social behavior when he was sick. This led him to hypothesize that there was a direct relationship between our physiological states and our social behavior. This insight was the starting point of the Polyvagal Theory.

Porges' research found that there are two branches of the vagus nerve in our bodies. The older, 'dorsal' branch, is responsible for the freeze response we exhibit in extreme danger. The newer, 'ventral' branch, helps us to be sociable and relaxed.

The Polyvagal Theory offers a comprehensive understanding of how humans oscillate between states of relaxation, alertness, and fear. It provides an intriguing perspective on how slight changes in our physiological states can significantly influence our emotional states, and the role of social interaction in regulating our nervous system responses.

The theory, thus, started from a father's concern for his son, eventually developing into an extensive explanation of our body's reactivity to different life situations. Therefore, each time we experience a surge of adrenaline or a state of calm, it's the Polyvagal Theory in action.

In the words of Dr. Stephen Porges himself:

"The polyvagal theory is a new paradigm for understanding the autonomic nervous system and its role in social behavior, emotional regulation, and health. It is based on the idea that the autonomic nervous system has evolved to support three distinct states of being: social engagement, mobilization, and immobilization.

The social engagement system is associated with feelings of safety, security, and connection. It is activated by cues that signal safety, such as the sight of a familiar face or the sound of a friendly voice. The mobilization system is associated with feelings of excitement, energy, and readiness for action. It is activated by cues that signal danger, such as the sight of a predator or the sound of a loud noise. The immobilization system is associated with feelings of fear, helplessness, and shutdown. It is activated by cues that signal extreme danger, such as the sight of a weapon or the sound of a gunshot.

The polyvagal theory suggests that our nervous systems are constantly assessing our environment for threats. When we perceive a threat, our ANS shifts into a state of high alert. This can lead to a number of physical and emotional changes, such as increased heart rate, rapid breathing, and sweating. If the threat is prolonged, our ANS can shift into a state of freeze. This is a natural survival mechanism that helps us to avoid danger."

Some studies have attempted to validate the primary claims of the theory.

For an overview of the theory and it's research abstract, start here with "The polyvagal theory: phylogenetic substrates of a social nervous system."

• Resting Vagal Tone and Vagal Response to Stress: Associations with Anxiety, Aggression and Perceived Anxiety Control among Youth: In short, this research enhances our knowledge about how resting vagal tone and changes in vagal activity during stress are linked with anxiety control beliefs, anxiety levels, and aggression in young people. The findings support Porges's theories and suggest that a low resting vagal tone could be a solid biological sign of anxiety in youth. More importantly, the study indicates that how the vagal nerve responds to stress could be a broad measure of emotional imbalance across both anxiety and aggression issues. Lastly, this research underscores the need to continue exploring the direct relationships between the biological aspects of emotional and behavioral disorders and the actual symptoms associated with these disorders. This can help us better understand the theoretical and empirical connections with such conditions.‍
• Cardiac vagal control as a marker of emotion regulation in healthy adults: A review: This review assesses 135 papers studying cardiac vagal control (CVC) as an emotion regulation marker in healthy adults. It considers both resting and phasic CVC measures. Positive connections were found between resting CVC and adaptive regulatory strategies with flexible emotional responses. Changes in phasic CVC are linked with stress levels and recovery. Despite some conflicting outcomes, the consensus supports CVC as a reliable, noninvasive indicator of emotion regulation.

There's also a rather large library of books written by clinical experts on the theory and use of Polyvagal Theory when working with mental health clients. I've provided a list below.

Some researchers have pointed out that not all assertions made in the Polyvagal Theory are verifiable or reproducible via their studies. According to a critical review of the research literature:

• Polyvagal (PV) theory claims relations between the vagus nerve & prosocial & emotionally defensive psychological functioning.
• Central is the conjecture that dorsal & ventral brainstem vagal centers differ in mediation of heart rate.
• Assumptions about vertebrate evolution play a significant role in PV theory, as evidenced by 5 basic, stated premises.
• The polyvagal theory also proposes that the vagus of mammals has been “repurposed” to enable sociality.
• Linchpin to PV theory is the phenomenon of respiratory sinus arrhythmia (RSA), employed as an index of cardiac vagal tone.
• This review evaluates each PV premise, as well as assumptions about RSA as index of vagal tone.

However, a thorough review of the theory's premises and the use of RSA as an index of vagal tone has concluded that these assumptions are not sustainable, based on both historical and current evidence.

In other words, the science doesn't directly substantiate the core hypotheses of the theory. That's not to say that the theory itself is absent of any value. That's not the case. After all, there's been broad recognition of the theory throughout the community of psychologists.

Although the exact mechanisms behind the theory might not have been irrefutably substantiated, the theory offers many compelling suggestions that are commonly put to use in clinical practice (e.g. the importance of social engagement in overall health and well-being.)

Here's a list of some of the most popular and highly-cited books.

• The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-regulation by Stephen Porges - This is the landmark book where Porges first introduced the Polyvagal Theory. It explains how our nervous system affects our emotions and our relationships with others.
• The Pocket Guide to the Polyvagal Theory: The Transformative Power of Feeling Safe by Stephen Porges - This is a simplified guide to Porges' theory. It talks about how feeling safe can change how we act and react to the world around us.
• Accessing the Healing Power of the Vagus Nerve: Self-Help Exercises for Anxiety, Depression, Trauma, and Autism by Stanley Rosenberg - This book provides practical exercises to activate the power of the vagus nerve to heal various mental and physical conditions.
• Clinical Applications of the Polyvagal Theory: The Emergence of Polyvagal-Informed Therapies by Stephen Porges and Deb Dana - This book is for therapists and professionals. It explains how to use the Polyvagal Theory in different types of therapies to help their clients.
• The Polyvagal Theory in Therapy: Engaging the Rhythm of Regulation by Deb Dana - This book, written by a clinician, offers therapists an insight into applying the Polyvagal Theory in their practice. It provides a guide to understanding and working with clients' nervous systems.
• Polyvagal Exercises for Safety and Connection: 50 Client-Centered Practices by Deb Dana - This book offers practical exercises based on the Polyvagal Theory that can help create a sense of safety and connection.

Here are some ways that you can apply polyvagal theory to yourself if it's something you wish to explore as part of your own wellness routine:

• Pay attention to your body. One of the key aspects of polyvagal theory is that our nervous system is constantly responding to our environment, and our bodies give us clues about how we're feeling. Pay attention to your heart rate, breathing, muscle tension, and other physical sensations. When you notice that you're feeling stressed or anxious, take a few deep breaths and try to relax your body.
• Identify your triggers. What are the things that tend to trigger your anxiety or stress? Once you know your triggers, you can start to develop strategies for coping with them. For example, if you know that you get anxious in social situations, you could practice deep breathing or visualization exercises before you go out.
• Connect with others. Social connection is one of the best ways to activate your parasympathetic nervous system and promote feelings of safety and well-being. Make an effort to spend time with people who make you feel good, and avoid people who make you feel stressed or anxious.
• Engage in activities that you enjoy. Doing things that you enjoy can help to reduce stress and anxiety. Find activities that make you feel relaxed, happy, and connected to yourself and others.
• Get regular exercise. Exercise is a great way to improve your overall health and well-being, and it can also help to reduce stress and anxiety. Aim for at least 30 minutes of moderate-intensity exercise most days of the week.
• Get enough sleep. When you're well-rested, you're better able to cope with stress and anxiety. Aim for 7-8 hours of sleep each night.
• Practice mindfulness. Mindfulness is the practice of paying attention to the present moment without judgment. It can be a helpful way to calm your mind and body, and it can also help you to develop a more positive outlook on life. There are many different ways to practice mindfulness, such as meditation, yoga, and tai chi.‍
• Grounding techniques. Grounding techniques help you to bring your attention back to the present moment and to feel more connected to your body. Some examples of grounding techniques include deep breathing, focusing on your senses, and naming five things that you can see, hear, smell, taste, or touch.‍
• Visualization techniques. Visualization techniques can help you to create a sense of calm and relaxation. One example of a visualization technique is to imagine yourself in a peaceful place, such as on a beach or in a forest.‍
• Affirmations. Affirmations are positive statements that you repeat to yourself. They can help to change your thinking patterns and to promote feelings of self-worth and confidence.