The Science of Yoga: Understanding the Benefits 

In this article, guest blogger Olivia Hazlitt delves into the science behind the benefits of yoga. While many people know that yoga is good for them, they may not understand the scientific reasons behind it. Olivia explores common notions about what happens during a yoga practice, backed by scientific evidence from neuroscience and other fields. Discover the “why” behind the benefits of yoga in this informative article.  

–The Science of Yoga: the “why” behind the benefits.

By: Olivia Hazlitt 

The benefits of yoga in my six years of practice have come at me with both immediacy and a slow seeping into my everyday interactions and feelings. Since my first ever class the post-class yoga high has been a constant in my practice. It features a floating bubble-like attitude to anything around me for about one hour after waking from savasana and a distinct detachment from worries and preoccupations. The slower, more difficult to identify symptom of a consistent practice, however, has shown up in an increased level of tolerance and compassion for other people and a subconscious contentment that seems to bolster me constantly. 

For me, these benefits were undoubtable. I knew yoga was giving me this pausing space between noticing and reacting, it was allowing me to feel confident during periods of change that used to paralyse me, and I just FELT more joyful. Now, when explaining this to someone you are often met with a bemused, rather condescending chuckle of disbelief of this remarkable side-effect to this “woo-woo” practice. 

So, I began to investigate the science of yoga and the neuroscience. Just to preface this discussion I think it’s worth saying that the desire to know “why” is an inherently western thought process that requires evidence-based research to validate and legitimise your feeling. The ancient yoga practice does not need to be proven to be justified as I feel this can sometimes belittle the many, many teachers of yoga, particularly in South Asia that came before me. 

So, let’s start with the immediate stuff 

The number one post-yoga benefit that is commonly spoken is that practitioners feel more relaxed. The feeling of calm and restoration comes from the stimulation of the parasympathetic nervous system which triggers the “rest and digest” response rather than the parasympathetic “fight or flight” response. The production of the stress hormone cortisol is therefore reduced. In a fascinating interview conducted by Dr Hazel Wallace of The Food Medic podcast, Dr Tara Swart, neuroscientist and former psychiatric doctor, explains that “women who do yoga 3 times a week have a lower level of the stress hormone cortisol compared to aged-matched controls who don’t”. 

Why is the parasympathetic stimulated? 

The element of the yoga practice that most affects the stimulation of the parasympathetic nervous system is the breath, or our pranayama practice (“Prana” = breath or life force, and “yama” = control). The breath, in particular the exhale, has been proven to stimulate the vagus nerve. The vagus nerve (VN) is a cranial nerve complex that relays relaxation from the central nervous system to the body and the activity of the VN is modulated by respiration. The VN is active when you breathe out and when you lengthen that breath. This is why pranayama practices such as where you breathe in for four counts and out for six counts are so powerful. The other crucial element is that your exhale is diaphragmatic, or in layman’s terms your stomach must rise. Upon more research into the VN, I found it is something woven into the basis of the Wim Hof method, founded by the eccentric dutchman that preaches the benefits of breathing techniques and cold-water exposure. 

On another fascinating note, 80% of the fibres are afferent, meaning they run from the body to the brain. As psychiatrist and author Bessel van de Kolk explains “we can directly train our arousal system by the way we breathe, chant, and move, a principle that has been utilised since time immemorial in places like China and India …that is suspiciously eyed as “alternative” in mainstream culture”. 

Why am I more tolerant? 

My family may disagree with this one but one of the overwhelming changes I’ve felt is that I snap FAR less. It feels as though I have more processing time where previously I wouldn’t even think about the situation, I would simply react to it. It’s like I can view myself from a third-party decision and have a little conversation with myself over whether this circumstance is worth spending energy over and often I choose not to react at all. This change, I believe, can somewhat be attributed to the stimulation of the parasympathetic nervous system that we have just discussed because when you are in a sympathetic state you are poised to attack like a lioness down on her haunches. 

The emotional centre of the brain: the amygdala. 

The brilliant book, “The Body Keeps the Score: Mind, brain and body in the transformation of trauma” by Bessel Van Der Kolk introduced me to the function of the amygdala, the emotional centre of the brain. The function of the amygdala is to warn us of impending danger and to activate the body’s stress response. Activation of this area through memory of trauma, stress or physical/emotional danger causes the HR and blood pressure to rise and fight or flight to kick in. 

Dr Swart in the podcast goes on to explain that with 2-3 months of regular practice (minimum 12 minutes preferably every day) we see physical changes in the brain. There is denser folding of the outer cortex which in turn regulates the amygdala. The effect of this is what she calls a “pause button” so if someone shouts at you, you don’t respond with a jerk reaction you take time to think of how to respond. 

Cultivating Santosha (contentment) and joy 

Santosha is one of the yogic principles and it roughly translates to “contentment”. A very common Vritti (fluctuation of the mind) that we all experience is “I’ll be happy when/if…”. Santosha encourages us to find contentment in what we have and what we are right now. You guessed it this can be somewhat explain by neuroscience. A study has shown that the activation of the parasympathetic nervous system via the vagus nerve slows the natural decline of grey matter that occurs with age in the regions of the brain associated with happiness and joy. AKA yoga makes you happier and continues to do so! 

Neuroplasticity and adapting to change 

Change has always been something that I struggle with. Before a big change be that moving country, job, or university I always experience anxiety that paralysed me into numbing my own emotions and to be quite frank just not doing anything at all. It is an ongoing journey, but I really feel yoga has helped me navigate more recent periods of change with more cool and perspective. A reason for this could be found in the research between yoga and increased neuroplasticity. 

Neuroplasticity is a general term that refers to the brain’s ability to modify, change, and adapt both structure and function throughout life and in response to experience (Frontiers in Psychology). The neural connections you must make as you experience a new asana, transition, or state of being increases neuroplasticity and thickens the layer of the cerebral cortex associated with higher learning. This means that we become more adapted to new information and a change in circumstance. 

Read more from the blog: Online Yoga: a symptom of Covid:19? 

References: 

Stellar, J. E., Cohen, A., Oveis, C., & Keltner, D. (2015) “Affective and physiological responses to the suffering of others: Compassion and vagal activity.” Journal of Personality and Social Psychology, 108(4), pp. 572-585. 

Salamon, M. (2013). “The Science of Yoga and Why It Works.” Live Science. 

Swanson, A. (2019). The Science of Yoga 

(2020). “The Science Behind Breathwork + 5 Benefits of the Practice” 

Gerritsen, R., & Band, G. (2018). “Breath of Life: The Respiratory Vagal Stimulation Model of Contemplative Activity.” Frontiers in Human Neuroscience, 12, 397. 

Dr Wallace & Dr Swart. The Food Medic Podcast. 

Thumbnail illustration: Caitlin Marie Miner Ong 

Last words

The benefits of yoga are both immediate and long-term, and they have personally impacted many practitioners. These benefits include feeling more relaxed, increased tolerance and compassion for others, and a greater sense of joy. Yoga can stimulate the parasympathetic nervous system, which triggers the “rest and digest” response and reduces cortisol production.

Breathing practices, or pranayama, are particularly effective in stimulating the vagus nerve and promoting relaxation. Regular practice can also lead to physical changes in the brain, including denser folding of the outer cortex, which regulates the amygdala and helps create a “pause button” before reacting to a situation. While ancient yoga does not require scientific proof, understanding the neuroscience behind the practice can help legitimize its benefits.

In conclusion, the article on somatic movement and the guest blog on yoga both emphasize the importance of cultivating a sense of contentment, or santosha, through movement and mindfulness practices.