As I mentioned in the last two blog posts, I’ve just finished reading a wonderful book reviewing the research to-date on yoga called The Science of Yoga: The Risks and the Rewards by William J. Broad. In the next blog post, I’m going to present an overview on the findings of the research on the benefits of yoga to nervous system. Understanding that requires some understanding of how your nervous system works. This will be the focus of this blog post.

A Quick Primer on the Nervous System

Your nervous system serves three main functions: gathering, synthesizing, and responding to stimuli. It is your nervous system that is in constant command of how your body reacts—the automatic, patterned way a stimulus affects you—and responds—the thoughtful way you can choose to behave in reaction to a stimulus—with thoughts, feelings, sensations, and behaviors.

There are two main parts to the body’s nervous system: 1) the central nervous system, which is comprised of your brain and spinal cord, and 2) the peripheral nervous system, which refers to the parts of your nervous system that are not in your brain or spinal cord. The peripheral nervous system is broken down into two categories: 1) the somatic nervous system and 2) the autonomic nervous system (ANS). The somatic nervous system refers to the nerve fibers that transmit sensory information to the central nervous system and the nerve fibers that tell our muscles to move. Your ANS is the part of your nervous system that operates without your conscious control and is responsible for such vital functions as perceiving danger, generating “gut reactions” to threatening stimuli, reacting to threats, facilitating connection with people, and coordinating the process of digestion.

The Autonomic Nervous System (ANS)

It is the ANS that perhaps benefits the most from the practice of yoga (and is the primary focus of my practice as a psychologist). Understanding how yoga improves ANS functioning begins with how the ANS works.

Your ANS is comprised of three different yet related systems that work together to coordinate various activities:

1. The Sympathetic Nervous System, your body’s “fight-or-flight” system. Think of it as a gas pedal. It’s a fast-acting system, and it needs to be. If a real threat to your life emerges, you need to be able to deal with it immediately. When the sympathetic nervous system is activated, your body is flooded with chemicals that energize your body and allow it to act swiftly in order to fight or fun for your life.
2. The Parasympathetic Nervous System, your body’s “rest and digest” system. Think of it as the brake pedal. It’s a slow-acting system that facilitates energy conservation in times of safety and ease and in times of extreme or traumatic stress. When we feel safe and at ease, the body can optimally rest and digest. When in a perceived life-threatening situation, the parasympathetic nervous system will generate a freeze response.
3. The Enteric Nervous System, often referred to as your body’s “second brain”. It is located in your gut, structurally looks a lot like your brain tissue, houses as many or more neurons than your spinal cord, and contains all of the same neurotransmitters (chemicals that facilitate the transmission of neural messages) that are contained in your first brain.