Why Yoga Works

Posted on August 30th, 2012 by in Studies, News, and Trends, Yoga

by Angela Wilson

Scientists offer an explanation of why Yoga increases well-being.

With the ever-growing amount of scientific studies conducted in the field of yoga research, it’s no surprise that we’re starting to get answers to the question: Why, exactly, does yoga work? Research has shown that yoga improves symptoms of a variety of conditions, providing relief from depression and anxiety, diabetes, chronic pain, and even epilepsy. Recently, the National Institutes of Health awarded several large grants to the study of yoga.

One such grant, given to Lorenzo Cohen, PhD, director of the Integrative Medicine Program at the University of Texas MD Anderson Cancer Center, explores the impact of yoga on the health of women with breast cancer. Another grant, awarded to Kripalu-affiliated researcher Sat Bir Khalsa, PhD, assistant professor in the Division of Sleep Medicine at Brigham and Women’s Hospital, supports a study to investigate whether Kripalu Yoga prevents or diminishes high school students’ use of illicit substances.

This has been an exciting time for yoga research, as more studies emerge that continue to shed light on how yoga is effective in alleviating many mental and physical health problems.

Researcher Chris Streeter, PhD, associate professor of psychiatry and neurology at Boston University School of Medicine, recently released an article, “Effects of Yoga on the Autonomic Nervous System, Gamma-aminobutyric-acid, and Allostasis in Epilepsy, Depression, and Post-traumatic stress disorder,” detailing what are believed to be the underlying physiological mechanisms, or, simply put, yoga’s impact on the body and brain.

Dr. Streeter and her team hypothesize that yoga helps regulate the nervous system by increasing what’s called vagal tone, or the body’s ability to successfully respond to stress. Improvements in vagal tone have been shown to correlate with reductions in allostatic load (the amount of stress we accumulate over time). The researchers believe that the reason yoga helps increase resilience and well-being is because of its positive impact on vagal tone.

So what’s the vagal tone all about? It’s directly related to the state of the vagus nerve, which is our largest cranial nerve. It’s also known as the “wandering nerve” because of its mobility through the body. The vagal tone starts at the base of the skull and travels throughout the body, touching the respiratory, digestive, and nervous systems. Often thought of as our “air-traffic controller,” the vagus nerve helps regulate all our major bodily functions. Breathing, heart rate, digestion, and even how we take in, process, and make meaning of our experiences are all directly related to the vagus nerve.

It’s easy to see, then, why the vagus nerve is critical to optimal physiological functioning, as well as a significant marker of resilience. People with healthy vagus nerve functioning are considered to have “high vagal tone,” meaning their bodies and brains are more resilient under stress. They have an easier time moving from an excited state to a relaxed one. Someone with high vagal tone, for example, would recover faster from a fight with a spouse than someone with low vagal tone. Not surprisingly, these individuals tend to be healthier and more resilient.

People with low vagal tone, on the other hand, are more sensitive to stress and disease. They tend to have challenges such as weak digestion, increased heart rate, and difficulty managing emotions. Interestingly, low vagal tone is correlated with such health conditions as depression, anxiety, chronic pain, and epilepsy—the very same conditions that show significant improvement with yoga practice. Researchers hypothesize that vagal stimulation through yoga may improve these conditions.

How else does this relate to yoga? A growing amount of research shows that yogic practices such as pranayama, or breathing techniques, significantly increase vagal tone. “Resistance breathing,” such as ujjayi (ocean-sounding breath), increase parasympathetic activity (the relaxation response) as well as heart rate variability—another marker of resilience.

As scientists begin to unravel how yoga works, yoga teachers, in turn, will continue to increase their understanding of which practices produce what responses, and why. Studies such as the ones above continue to produce fascinating insight into the science of yoga, helping researchers such as our Kripalu-affiliated scientists fine-tune their measures as they explore yoga’s impact on various health conditions.

© Kripalu Center for Yoga & Health. All rights reserved. To request permission to reprint, please e-mail editor@kripalu.org.


About Angela Wilson, MA, RYT

Angela is a faculty member for Kripalu Healthy Living programs and Project Leader for the Institute for Extraordinary Living’s Front-Line Providers program, supporting health-care workers to find balance through the practice of yoga. Angela holds a master’s degree in mental-health counseling from Lesley University and has contributed to Yoga International and Yoga Therapy Today, writing about the intersection between yoga, Western psychology, and science.

8 Responses to “Why Yoga Works”

  1. Sheila Levenhagen August 30, 2012 12:32 pm #

    At least 30 years ago my mom had a vagotomy. I have recently taken a real interest in restorative yoga and have begun to see these articles about the vagus nerve, like the one above, and wonder if a vagotomy could have anything to do with chronic depression or anxiety. If so, what can she do for herself?

  2. KripaluEditor September 3, 2012 10:08 am #

    Hi Sheila,
    Yoga has been shown to reduce anxiety and depression.Your mom could try the intervention that was suggested in the blog–basically the ocean breath for several minutes.The constriction in the back of the throat and the breathing itself will stimulate and balance her body and mind.
    Best to you,
    Kim from Kripalu

    • Sheila September 5, 2012 2:30 pm #

      Thanks for taking the time to attend to my question. I am now a yoga instructor – just getting certified. Kim, I just wondered if the procedure itself was any possible cause of depression or anxiety issues. Namaste

  3. Brenda Stark-Yasinski July 22, 2013 11:49 pm #

    Hi – Our daughter is 17 yr’s. old – Uncontrolled Epilepsy, speech & dev. delayed, apraxia, dystonia and recently at Christmas spent a wk. in hosp. with Catatonia – just recently a program thru school was started for Lauren for O/T – and now following up in the community with same therapist. I was told Yoga was a great tool and breathing techniques and was hoping I could find some yoga positions that you might feel would be beneficial for her. ( The Clam was one they did with her today at Clinic ). She wears a shoe orthodic in her right shoe to correct the abnormal placement of her right knee – trying to cause a smoother gait. Thank-You, Brenda Y.

    • KripaluEditor July 23, 2013 8:08 am #

      Hi Brenda,
      I will reach out to our faculty and get back to you soon.
      Sending you and your daughter the best,
      -Kim from Kripalu

      • Brenda Stark-Yasinski July 23, 2013 3:27 pm #

        Thank-You very much Kim :D

        • Angela Wilson, MA, RYT
          Angela Wilson July 24, 2013 9:07 am #

          Hi Brenda!
          Yoga is a great tool to help regulate the nervous system and to improve vagal tone (something that often gets impacted with conditions such as epilepsy). Studies point to yoga in general being beneficial for this condition. However, if you are curious about specific poses or breathing techniques that might be most suited for epilepsy (since there are so many different kinds of yoga) I would see if you can find a yoga therapist in your area. They would have more knowledge on specific practices to support your daughter’s recovery.
          Angela Wilson from Kripalu

          • Brenda Stark-Yasinski July 24, 2013 10:31 am

            Good Morning Angela :D
            – Great, I will tap into some local yoga instructors for a plan :)
            ~ Have a great day! Bren.

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