How Yoga Affects the Brain and Body to Reduce Stress

By Vanika Chawla, MD, Stanford Psychiatrist

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As a clinician at the Stanford Lifestyle Psychiatry clinic, I consider the impact of lifestyle factors such as sleep, nutrition, exercise, and mind-body practices such as yoga on my patients’ mental health and integrate these modalities into my treatment plans. I especially have a clinical and research interest in the therapeutic use of yoga as a lifestyle intervention. Yoga has been instrumental in my own wellbeing, therefore I am passionate about sharing the practice as a holistic intervention that promotes wellbeing in the body, mind, and spirit.

I was first immersed in yoga when I completed my 200-hour yoga teacher training in 2010, prior to medical school. I discovered that yoga was much more than physical postures – yoga is an integrative and holistic system of practices that aims to alleviate suffering. 

There are many different lineages and traditions of yoga, each emphasizing various components of the practice, including postures, breathwork, meditation, lifestyle, ethics and values, and recognizing our interconnectedness. There is a famous aphorism that captures the essence of yoga: yogas chitta vritti nirodhah. This Sanskrit phrase translates to, “Yoga is the calming of mental fluctuations or storms of the mind.” Thus, it was no surprise that on my journey to become a psychiatrist, I noticed parallels between yoga and psychiatry, including yoga’s therapeutic potential in addressing unmet needs in our current mental health care treatment models. 

On a personal note, my yoga practice provided me with a set of tools to manage the stresses and rigors of medical training, whether it was cultivating new perspectives when faced with challenges or practicing breathwork before a big exam to help with stress. 

How Yoga Improves Mental Health

While yoga is an ancient practice originating in India, it has only recently been applied for therapeutic purposes, and thus, the clinical evidence is in its early stages. There are many possible mechanisms for how yoga may improve mental health and counteract stress. One well-accepted mechanism is that yoga helps regulate the autonomic nervous system (ANS) and hypothalamic-pituitary axis (HPA), both of which are stress response systems. While stress is an inevitable and necessary part of life, prolonged and chronic stress can lead to dysfunction in these systems, potential negative physiological and physical consequences, and can even contribute to the development of mental health disorders. 

Yoga is proposed to exert its benefits through top-down and bottom-up processes facilitating bi-directional communication between the brain and body. Top-down mechanisms are conscious and intentional inputs from the brain to the body, such as setting an intention to relax. Bottom-up processes are inputs from the body to the brain, where signals travel from the muscles, heart, lungs, and other systems to different parts of the brain. Practices like yoga postures and breathing can change the signals that are carried to our brain, such as assessments of our sense of safety and wellbeing. Through top-down and bottom-up pathways, yoga can counteract the “fight, flight, or freeze” responses that may persistently arise in the face of stress. Accordingly, yoga has been shown to confer several changes in physiological markers implicated in stress, including cortisol, inflammatory cytokines, heart rate variability, as well as the release of neurotransmitters, such as GABA. 

The Neuroscience of Yoga

In addition, there is evidence of changes in both brain structure and function related to the practice of yoga. These include changes in the prefrontal cortex (PFC), amygdala, hippocampus, and default mode network (DMN). The PFC manages our highest-order cognitive abilities, such as decision-making and goal-setting. Stress and other strong emotions can negatively impact the abilities of the PFC. 

Research shows that regular yoga practice leads to increased activation of the PFC and thus may counteract deleterious effects of stress on the brain. Further, yoga impacts the activity of the amygdala, which is involved in processing emotions. Yoga may also increase the volume of the hippocampus, which is involved with memory and learning and is known to decrease in size with age. Finally, the DMN is involved in rumination and mind wandering, which may interfere with cognitive function and lead to decreased wellbeing. The DMN is implicated in many psychiatric disorders, such as depression and ADHD, and yoga has been shown to modulate the activity of the DMN. 

While yoga cannot change our external stressors, it can allow us to respond rather than react to stress. Yoga can counteract the harmful physical effects of stress and lead to changes in the body, brain, and mind that increase resilience and adaptability. 

Tips for People New to Yoga

From Kundalini to Vinyasa flow, there are many different types of yoga, so I recommend those new to yoga try different styles and see which practice aligns with their needs and feels safe and supportive. I suggest taking classes from credentialed teachers (with a minimum of RYT-200 hr training) who offer modifications and adaptations. There are resources like Yoga-X online classes, which provide holistic yoga practices at no cost. If you are seeking yoga for a specific health or therapeutic purpose, then community classes may have limitations. You may instead look for therapeutic yoga classes or yoga therapy in conjunction with support and consultation from your healthcare provider.