You’ve probably heard about the nervous system in all its glory and how yoga can have a positive effect on it. You may have heard about specific yogic techniques that can help to downregulate and calm your nervous system. And you may have even heard about specific branches of the nervous system.
But do you really understand the intricacies of this complex system and all it entails? Truthfully, while not even neuroscientists fully understand all of the ins and outs of the nervous system, some essential aspects are known, and there’s growing evidence that yoga can help to regulate it.
What Is the Nervous System?
The human nervous system is a wildly complicated and largely uncharted part of the body that transmits electrical and chemical energy to initiate movement, identify threats, perform digestion, regulate heart rate, execute respiration, create thought, and so much more.
It’s divided into two main branches, and contrary to what many believe, they are not the sympathetic and parasympathetic systems; rather, they are the central nervous system and the peripheral nervous system.
The central nervous system includes the brain and spinal cord. The peripheral nervous system includes all nerve tissue found outside the central nervous system, including nerves and ganglia (clusters of neuron cells).
The peripheral nervous system is further divided into the autonomic nervous system (which controls involuntary functions like breathing) and the somatic nervous system (which controls voluntary functions like walking).
What Is the Autonomic Nervous System?
As the center of involuntary functions, the autonomic nervous system is further subdivided into the sympathetic nervous system (the “fight-or-flight” branch), the parasympathetic nervous system (the “rest-and-digest” branch), and the enteric nervous system (the gut branch).
While yoga has the potential to affect all parts of the nervous system, yoga teachers and practitioners tend to be primarily concerned with the sympathetic and parasympathetic systems because they are the parts of the nervous system that we can influence more directly through our practice.
What Is the Sympathetic Nervous System?
The sympathetic nervous system is often referred to as the “fight-or-flight” response. This is the branch of the nervous system responsible for alerting the body to potential danger.
When we experience a perceived threat, our heart rate elevates, our pupils dilate, and our respiratory rate increases, sending freshly oxygenated blood to the brain. Our bodies are also pumped with neurotransmitters and hormones like epinephrine and norepinephrine, which regulate everything from breathing and heart rate to mood. Our digestive system mostly shuts down as precious oxygen-rich blood is moved toward our skeletal muscles. This and so much more happens essentially in the blink of an eye. These changes ultimately prepare us to fight the threat or flee the scene. This is why our sympathetic response is often analogous to the gas pedal of a car. When we put the pedal to the metal, we are propelled forward at full speed.
And yet, as intelligent as our bodies are, our sympathetic nervous system has not caught up with the changes in our lifestyles. Our bodies, for instance, cannot properly differentiate between the stress of a life-threatening situation and the stress of an important work meeting. Ultimately, our bodies perceive the threat of a nagging boss in the same way that we perceive the threat of a lion charging toward us.
Moreover, this sort of stress can become chronic. Persistent and relentless email notifications from work arriving every night after we’ve clocked out can condition us to remain in a sympathetic state, chronically stressing our body and mind and potentially leading to a plethora of stress-related ailments. Beyond that, chronic stress can signal our endocrine system to produce more stimulating hormones, which can then perpetuate the cycle of stress response in our body.
But despite its negative reputation in the yoga world, the sympathetic nervous system is actually a crucial part of our entire being. Not only does it keep us safe in the face of danger, it’s also an important piece of the intricate full-body matrix that balances our bodies overall.
In fact, we activate the sympathetic nervous system all the time in our yoga practices. More dynamic, faster-paced flows and longer (more challenging) holds stimulate the sympathetic response. When we jump back to chaturanga, we elevate our heart rate. When we stabilize in inversions, our blood is readily flowing to our skeletal muscles. When we balance in warrior III, invigorating neurotransmitters are released and energizing hormones are pumping through our veins. We also activate this aspect of our nervous system when we do vigorous forms of exercise, like running.
So, it is actually incredibly healthy and normal to stimulate the sympathetic nervous system.
What Is the Parasympathetic Nervous System?
The parasympathetic nervous system is often referred to as the “rest-and-digest” response. This part of the autonomic nervous system counters the sympathetic response.
Often called the “brakes” of the nervous system, the parasympathetic nervous system slows heart rate, stimulates digestion, decreases respiratory rate, moves blood flow away from extremities and back toward vital organs, releases soothing neurotransmitters like acetylcholine, and so on.
This system is often put on a pedestal in yoga practice because it helps us to relax our excessively stressed bodies and minds. We use practices like restorative yoga to specifically target it and move us into more relaxing states.
But just because this division of the nervous system is typically glorified in the yoga world, doesn’t mean it is necessarily a more desirable place to be all the time. It’s healthy to be able to fluctuate between both the sympathetic and the parasympathetic systems effortlessly. And we can actually measure this fluctuation throughheart rate variability.
Heart Rate Variability
Naturally, when a healthy individual breathes in, their heart rate elevates slightly, stimulating their sympathetic nervous system. When they breathe out, their heart rate decreases slightly, stimulating their parasympathetic system. This variability in heart rate is a good marker of overall health and wellness. Generally, the more the body is able to fluctuate quickly and easily between the sympathetic and parasympathetic nervous system, the better the overall health of the nervous system as a whole.
Someone who is chronically “stuck” in the stress response would have poor heart rate variability, since their heart rate would probably be chronically elevated. On the other hand, someone who has a healthy balance in their autonomic nervous system would have high heart rate variability, since they can easily downregulate their nervous system after a stressful situation.
We want to be able to react instantaneously to stress. But we also want to be able to easily calm down when the stress has passed. This is where yoga plays a role.
How Does Yoga Affect the Autonomic Nervous System?
There are many different ways we can affect the autonomic nervous system through yoga. The following are just a select few ways that yoga can help to stimulate different parts of our autonomic nervous system.
As mentioned, exercise and dynamic styles of yoga—like Ashtanga, power, or vinyasa—can stimulate the sympathetic nervous system. This is a healthy and normal response to vigorous movement that helps to strengthen immunity, improve respiratory function, increase cardiovascular health, and so much more.
Restorative yoga offers the opposite effect. As the name implies, restorative yoga is very soothing and relaxing for both the body and the mind. It helps to stimulate what is called the relaxation response and moves our nervous system into its parasympathetic mode, promoting calm, feelings of safety and comfort, healthy digestion, and more.
Pranayama is a really quick and effective way to influence the autonomic nervous system. In fact, as mentioned above, we affect the autonomic nervous system with every single breath we take (heart rate variability).
Since a part of the vagus nerve runs through the larynx and the respiratory diaphragm, breath also affects vagal tone. Vagal tone is the measure of activity in our vagus nerve. The vagus nerve has many parasympathetic fibers, so the more stimulation it gets, the more our parasympathetic nervous system activates.
Certain breathing techniques, such as lengthening our exhalation, are particularly associated with the parasympathetic system and can help move our body into its “rest-and-digest” response. Alternatively, emphasizing the inhale could have the opposite effect.
Closing our practice in savasana can also impact our autonomic nervous system Because it encourages stillness and introspection, this pose can help to slow heart rate, respiration rate, and more, especially after a stimulating, dynamic practice. Despite its seeming simplicity, savasana is an extremely helpful practice for initiating a parasympathetic response and downregulating the nervous system.
Meditation is another practice that has down regulating effects. As we move into a place of physical and mental stillness, we start to release chronically held tension and stimulate the parasympathetic nervous system.
Balance Is the Key to Our Yoga Practice and to Our Overall Health
Everything within our bodies is constantly trying to work in congruence and harmony to achieve overall homeostasis.
We live in a stressful world, so most of us could benefit from practices that stimulate our parasympathetic response. But that doesn’t mean that we should completely neglect the sympathetic branch. Remember: The true marker of health is not which system is activated, but how efficiently, effectively, and quickly we are able to transition between systems.
After all, we need both a gas pedal and a brake to move forward in life. We just need to be able to use the appropriate tool at the appropriate time so that we don’t run full speed ahead into a brick wall. And luckily, we have yoga to help us navigate the way.