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How Yoga Can Balance the Vagus Nerve
Polyvagal Theory (PVT) has gained considerable attention among health professionals since a book of the same name was published in 2011. Based on brain science, the theory describes how information exchanged between the brain and body affects self-regulation, resilience, and how we interact with others.
The vagus nerve is a key player in the autonomic nervous system (ANS). The ANS regulates breathing, heart rate, blood pressure, digestion, and other automatic functions. The nerve is a communication super highway, sending a nonstop stream of information between the brain and organs like the heart, gut, lungs, and muscles of the face and head. A whopping 80% of those signals travel from the body to the brain, making the vagus a major player in interoception - the awareness of what is going on in your body. It’s what prompts you to reach for food when your stomach is empty, and why your mood shifts from crabby to happy when your stomach starts to fill. It can also lead to changes in your facial expressions and even the tone of your voice depending on whether you’re stressed or relaxed.
Interoception is a major focus of mind-body therapies like yoga. Through mindful movement, breathing, and observing thoughts and reactions, we become more attuned to what is going on inside. We also gain a safe space to challenge our thoughts, feelings, and reactions and play with different ways of responding. Much of this occurs because of the mind-body link created by the vagus nerve.
The Three Brain Complexes of Polyvagal Theory (PVT)
Dr. Stephen Porges, creator of PVT, proposed that the autonomic nervous system includes three brain “complexes:” ventral vagal complex (VVC), sympathetic nervous system (SNS), and dorsal vagal complex (DVG). These complexes work together to respond to moment-to-moment experience.
The ventral vagal complex (VVC) controls the “social engagement system.” This network of nerve fibers coordinates movement of the muscles of the face and head with functions of the heart and lungs. When we are at ease, this system supports prosocial behavior, enhancing facial expressivity, increasing listening skills, and even making the voice more relaxed.
The sympathetic nervous system (SNS) is best known for fight and flight behaviors. When facing threat or challenge, the SNS unleashes stress hormones like adrenaline and noradrenaline into the blood stream, boosting heart and breath rates, elevating blood pressure, increasing muscle tone, and stunting nonessential functions like digestion and sex drive. Activation of the SNS is also linked to fear, anger, aggression, and avoidance.
Lastly, the dorsal vagal complex (DVC) is a collection of vagal nerve fibers linking the brain to organs located below the diaphragm like the gut, kidneys, and bladder. It is nature’s emergency brake. This system gets activated in circumstances of intense trauma or distress, leading to immobilization, collapse, and even a loss of consciousness. Fainting goats provide an amusing example of what this looks like. Unlike the goat’s quick recovery, in the extreme, DVC activation in humans can lead to death.
Although the three brain complexes are separate and distinct, they often work together. For example, the VVC and SNS pair up when we participate in social activities that require connection and energy like dancing, playing, writing, or practicing yoga postures. Social situations that require stillness without fear such as listening to others or nursing a baby occur thanks to the integration of the VVC and DVC. "
Mind-body therapies like yoga are ideal for learning how to “turn these complexes on and off” because they give us ample opportunity to experience challenge and relaxation within a social setting. Practices give us a living laboratory where we can safely explore our minds, bodies, and emotions, and try different ways of attuning our responses to the challenges we face on and off the mat. This requires that we exercise each of these systems and learn how to balance them when the need arises.
Yoga and the Gunas
Ancient yogis were on to something when they conceptualized the gunas centuries ago. Described in the Samkhya Karia, an influential ancient yogic text, yogis believed that material experience, or Prakriti, had three major qualities: sattva, rajas, and tamas. These three qualities are similar in many ways to the complexes proposed in Polyvagal Theory.
Sattva is the term used to describe a quality of calmness, harmony, pleasure, clear thinking, and understanding. Although it was not directly related to the vagus nerve at the time, the quality of sattva is remarkably similar to the relaxed state that arises with the activation of ventral vagal complex (VVC) and parasympathetic nervous system (PNS).
Unlike Polyvagal Theory, ancient yogis cautioned that an excess of calm, joy, or pleasure might lead to an unhealthy desire to remain in these happy states leading to an avoidance of challenging experiences or even disillusionment or suffering when feeling good ends.
Rajas refers to an energetic state than can stimulate creativity, motivation, activity, and movement. It is an adaptive response to environmental challenges like pain or distress or other circumstances that require action. Parallel to excessive or chronic activation of the sympathetic nervous system (SNS) that can occur with prolonged states of stress or distress, yogis believed that excessive rajas interfered with the ability to see things clearly, and was linked to anger, pain, agitation, and anxiety.
Lastly, tamas is related to a capacity for self-restraint and regulation, as well as a lack of energy or motivation, or the presence of delusion and indifference. As with the activation of the dorsal ventral complex (DVC), the quality of tamas is necessary for stability, groundedness, and stillness. In the excess, tamas may lead to ignorance, negligence, apathy, and depression.
Similar to the three brain complexes proposed in Polyvagal Theory, the gunas were believed to engage in a dynamic dance that gave rise to thoughts, feelings, personality, and behavior. The yogis believed that suffering occurs when one or more of the gunas becomes dominant or imbalanced. The balancing of these qualities is essential to physical and mental health and the central focus of the practices embedded in many of the limbs of yoga.
What We Can Learn From Polyvagal Theory and the Gunas of Yoga
The ultimate life lesson from Polyvagal Theory and the gunas is that the nervous system is engaged in a dynamic, continuous dance. The body, in large part by way of the vagus nerve, provides a constant flow of sensory information to the brain and, in the ideal, the brain interprets those sensations and orchestrates a healthy response.
Each of the brain complexes or gunas serve an important function with neither being better or worse than the other. When out of balance, these systems can each contribute to different forms of suffering. Yoga and other mind-body therapies provide us with the opportunity to exercise our minds and nervous systems, and to safely experiment with different approaches for responding to life’s experiences in the healthiest way possible.
B Grace Bullock, PhD, E-RYT 500 is a psychologist, research scientist, educator, yoga and mindfulness expert and author of Mindful Relationships: Seven Skills for Success - Integrating the Science of Mind, Body and Brain. Her mission is to reduce stress, increase health and well-being and improve the quality of relationships. She offers classes, workshops, writing and research that combine the wisdom of applied neuroscience, psychophysiology, psychology and contemplative science and practice. Her goal is to empower individuals, groups, leaders and organizations to reduce chronic stress and increase awareness, attention, compassion, mindfulness and effective communication to strengthen relationships, release dysfunctional patterns and unlock new and healthy ways of being. Dr. Bullock is also the Founding Director and Principal Consultant of the International Science & Education Alliance, an organization devoted to exceptional research, program evaluation, assessment design, strategic planning and capacity building to support equity, programmatic diversity and scientific integrity, and promote effective leadership, decision-making and social change. Bullock is a Certified Viniyoga Therapist and Faculty at the Integrated Health Yoga Therapy (IHYT) Training program. She is the former Senior Research Scientist at the Mind & Life Institute and former Editor-in-Chief of the International Journal of Yoga Therapy. For more information see www.bgracebullock.com.
Sullivan MB, Erb M, Schmalzl L, Moonaz S, Noggle Taylor J & Porges SW. (2018). Yoga therapy and Polyvagal Theory: The convergence of traditional wisdom and contemporary neuroscience for self-regulation and resilience. Frontiers in Human Neuroscience, 12 (67), https://doi.org/10.3389/fnhum.2018.00067