© 2020 Alice Holmes Yoga

Yoga, breath and the autonomic nervous system


Mostly, I don’t feel a need to understand the ‘science’ behind yoga. For me, and for many of the people I know and teach, it works. Often I don’t know why, often I go to my mat in one state and leave in a different state. My analytical mind seems to be left at the door and I don’t have a strong desire to work out what is happening. What I know on a personal level is that connection with my body and breath brings about a change in state, a deeper connection to my inner world, my body, my self.



However, I do find the science fascinating. And however much I move away from my own rational, logical brain, I do believe strongly in our own incredible capacity to heal and self-regulate our mind-body, whatever it’s story. And that is where the science becomes fascinating. We can see, in real time, how it is healing itself.


Our autonomic nervous system is one of our body’s main messaging systems, which connects our body to our brain (and brain to body) to help us respond to the things that are going on in our external and internal environment. It communicates quickly, often automatically as the name suggests, and helps us to survive. It does this by sending messages to our muscles, our heart, our brain, our lungs, our digestive system, our adrenal glands. If we perceive a threat, everything is sped up, activated, ready for fight or flight.


This fight or flight (or freeze) response is our sympathetic nervous system in action. And we need this, for survival. The problem arises when it is always activated. We are constantly switched on, hypervigilant even. And this is what we see more and more in the western world. We have competing demands for our time, we don’t slow down, we are always busy, always ‘on’.

This works for us for a while, but then it can start to take its toll. Chronic stress, sleep problems, anxiety, depression, to name but a few. The constant activation of the sympathetic nervous system changes the internal physiology in our body and brain.


There is increasing evidence that yoga changes this state. Yoga and breath work takes us from a state of predominant sympathetic nervous system activation to predominant parasympathetic nervous system activation (or at least a balance). And the parasympathetic nervous system isn’t just about relaxation, it is also about emotional regulation, social connection, bonding and metacognition (and much more!).

I have been reading about the effect of the breath, and the pathways through which our breath can alter our internal state. Our exhale is directly linked with parasympathetic nervous system activation, so if we make it slightly longer, maybe double the length of our inhale, we can change our internal physiology. This body of ours is super cool.


Similarly, for balance we can try coherent breathing – an equal length of inhale and exhale, through the nose, 3-6 breaths per minute.


Much of this effect is mediated by the amazing vagus nerve which is so intrinsically linked in with all of the major regulatory systems in the brain (and body). And the science shows that we can change measurable things; our heart rate, blood sugar, inflammation, cortisol, blood pressure, heart rate variability, all in a positive way.


So your yoga is doing its magic. And whether you want to see it as magic or as science, the effects can’t be denied. Recent figures suggest that 10% of the UK population practice or have practiced yoga, there must be something that keeps them going back…what is it for you?

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