Why Yoga Works

Lesson Overview

In this lesson, we explore yoga’s impact on the nervous system and stress.


Become proficient in communicating how yoga practices impact the nervous system and why this is a critical factor in the positive results from yoga practice.


Understand why it’s important to learn to regulate the nervous system and give inspirational examples of yoga’s impact. Describe the primary underlying reason that yoga helps to relieve stress and give examples of yoga techniques that trigger the Relaxation Response. Describe the relationship between yoga, vagal tone, and relaxation. Explain research findings on the effect of Ujjayi Pranayama as it relates to stress. Define GABA and explain how it’s related to stress, fear and anxiety. Describe research findings on the impact of yoga on GABA levels.

Introduction & Inspiration

  • Chronic stress is known to both cause and exacerbate disease, and can lead to other problems such as anxiety or depression.
  • We know that a balanced nervous system is the key to positively managing stress.
  • In addition to these facts gained from the study of nervous system anatomy, we can inspire and teach through personal experience and stories. This insightful comment from Max Strom may help to set the tone:

Learning To Heal & Regulate Our Nervous System

How important is it that we learn to heal and regulate our nervous system? Consider this: who would you rather have babysitting your child? Someone who is tense and anxious and has trouble staying focused, or someone who is focused, calm, and happy? Which surgeon would you prefer operate on your brain or heart? One who is tense and anxious and sleep deprived, or someone who is focused, calm, and well rested? So, how important is it that we learn to heal and regulate our nervous system? The answer is obvious isn’t it? Learning to regulate our nervous system is every bit as important as exercising our body. In context to our relationships it is arguably far more important. – Max Strom

There is certainly no shortage of inspirational stories related to stress and yoga, and you likely have your own! See here for another from Baxter Bell, a medical doctor, yoga teacher and author. And the following quote is another excellent reminder that we typically can’t “just stop” stressful thoughts or the cascade of bodily responses!

Truth About Stress

Of course when you are stressed out, you can’t just tell yourself to relax. (I remember when I was suffering terribly from chronic stress, a therapist told me to “stop worrying.” I said, “Are you kidding?” and, duh, never went back.) But this is where yoga performs so brilliantly. – Nina Zolotow 

The Primary Reason

What are the underlying reasons why yoga helps to relieve stress?

It Triggers the Relaxation Response

Arguably the primary reason that yoga helps to relieve stress is because many yoga practices trigger the Relaxation Response. Examples include:

What Is Relaxation?

The antidote to stress is relaxation. To relax is to rest deeply. This rest is different from sleep. Deep states of sleep include periods of dreaming which increase muscular tension, as well as other physiological signs of tension. Relaxation is a state in which there is no movement, no effort, and the brain is quiet. —Judith Lasater

Increases & Sustains Vagal Tone

In a closely related point, some yoga practices indirectly stimulate the vagus nerve and help to sustain vagal tone, encouraging a healthy shift from the Fight or Flight Response to the Relaxation Response. Examples include:

  1. Brahmari Pranayama
  2. Ujjayi Pranayama
  3. Nadi Shodhana Pranayama
  4. Chanting
  5. Lovingkindness Meditation

Diaphragmatic Breathing Activates Relaxation Response

Diaphragmatic breathing activates the relax-and-digest response by stimulating the primary mediator of the parasympathetic nervous system, the vagus nerve… As you develop the skill of breathing from the diaphragm in the course of your daily activities, you will begin to experience your breath as a barometer for the nervous system. As long as you are breathing deeply and from the diaphragm, you will find that you can access a feeling of calm and balance even when you are confronted with an unpleasant situation. And you will also notice that if you allow your breath to become shallow by breathing from your chest, anxiety creeps in, your muscles tighten, and your mind begins to race and spin. – Carrie Demers, MD

Many Benefits from Breath Practices

Vagal tone increases during exhalation. By slowing down our respiration through deep, intentional breathing and elongating our exhalation, we can activate the vagal brake and elicit the relaxation response almost immediately. Once this response is initiated and PNS is dominant, our brains cease to be governed by the limbic system and fear circuitry that limits our capacity to effectively think, plan, reason and respond to others. This means that we are no longer subject to a narrow range of defensive or escape behaviors. Through intentionally deepening the breath and prolonging exhalation, we access not only the relaxation response, but also the capacity to be mindfully present in relationship. – B. Grace Bullock PhD

More Reasons

Other reasons why yoga helps to relieve stress include:

  1. Stress causes a rapid breath rate and yoga can slow the breath down.
  2. Slower, diaphragmatic breathing helps to balance the pH level of the blood.
  3. Releasing tension in the psoas is related to relieving stress.
  4. The stress response includes not only such activities as increased heart rate, but also particular muscular contractions. Yoga practices help to release muscular tension induced by such a stress response.

Decrease Rapid Breathing Caused by Stress

Chronic stress can disrupt the normal balance between your brain and your respiratory system by causing unhealthy breathing patterns. That’s because when you are stressed and triggering your fight-or-flight response, your brain reacts by stimulating your respiratory system to take in more oxygen to prepare you for action. But if you’re chronically just “feeling” stressed, you don’t actually need to take action, though you’ll still be breathing as if you do. By using yoga stress management techniques and spending more time in a state of relaxation, you can rebalance your brain’s input to your respiratory system and re-establish healthier, more appropriate breathing patterns. – Baxter Bell MD

Slower Breathing Balances Blood pH Level

In stressful times, we typically breathe too rapidly. This leads to a buildup of oxygen in the bloodstream and a corresponding decrease in the relative amount of carbon dioxide, which in turn upsets the ideal acid-alkaline balance—the pH level—of the blood. This condition, known as respiratory alkalosis, can result in muscle twitching, nausea, irritability, lightheadedness, confusion, and anxiety. In contrast, slowing the breath raises the carbon dioxide level in the blood, which nudges the pH level back to a less alkaline state. As the blood’s pH changes, the parasympathetic nervous system calms us in a variety of ways, including telling the vagus nerve to secrete acetylcholine, a substance that lowers the heart rate. – Richard Rosen

Undoing the Stress Response

Part of the stress response hardwired into our nervous system is the contraction of the major flexors of the torso—somewhat like the response of a caterpillar if you poke it with a twig. A verbal jab from a co-worker, the close call on the freeway, a long-standing argument with your spouse, free-floating anxiety—all of these elicit a contraction in the flexors. This is the tightening in the gut, the hunching of the shoulders, the sinking of the heart. As with all responses to stress, the problem is that the response becomes habitual, resulting in chronic tension and contraction, which we then experience as our “normal” state. Our yoga practice is an opportunity to undo this chronic tension, and establish a deep and abiding sense of harmony in the body and mind. – Sandra Anderson

Research on Vagal Tone

A number of articles refer to findings from studies authored by Chris Streeter, MD, associate professor of psychiatry at Boston University School of Medicine and Boston Medical Center. Streeter’s research is published in Medical Hypotheses Journal.

In Scientific Research: How Yoga Works, Angela Wilson highlighted these study results:

  • Chris Streeter’s study hypothesized that yoga works to increase the body’s ability to successfully respond to stress by increasing vagal tone and thereby regulating the nervous system.
  • Ujjayi Pranayama was shown to increase the relaxation response and heart rate variability (a function of stress resilience).
  • Chanting Om out loud increased vagal tone and the relaxation response more than chanting it silently.

Research on GABA Levels

What is GABA?

  • GABA is a neurotransmitter that sends messages through the nervous system, and is involved in regulating communication between brain cells.
  • GABA plays an important role in behavior, cognition, and the body’s response to stress. Research suggests that GABA helps to control fear and anxiety, while low levels of GABA in the brain have been linked to schizophrenia, depression, anxiety, and sleep disorders. (Everyday Health)
  • Classical anti-anxiety medications work by encouraging the release of GABA. And GABA is what alcohol mimics, by temporarily binding to the same chemical receptors. (Psychology Today)

Yoga Increases GABA Levels

Studies by Streeter and colleagues demonstrate that regular practice of gentle yoga, but not walking, releases a chemical called GABA in the thalamus…  GABA was shown to be significantly higher in the brains of those subjects who had been doing yoga. The study also compared GABA levels directly before and after an hour of yoga, and showed a 27% increase! – Rachael Grazioplene

More Research

See Research on the Impact of Yoga for many research summaries. For example, Psychology Today shares results from a study conducted in 2015:

Keeps Brain from Shrinking with Age

A new, May 2015 study published in the Frontiers in Human Neuroscienceuses magnetic resonance imaging (MRI) of the brain to show that yoga protects the brain from the decline in gray matter brain volume as we age. People with more yoga experience had brain volumes on par with much younger people… This finding has also been true in brain imaging studies of people who meditate. In other words, yoga could protect your brain from shrinking as you get older. – Marlynn Wei MD

See Also