Yoga is often touted as a method of connecting the body, mind, and spirit, and one of the ways that we do this is by practicing different breathing exercises, or pranayama. Even when the focus is on asana, we are often reminded to take “one movement, one breath,” and use breathing techniques as a way to concentrate. Have you ever wondered why? Modern science confirms what centuries of yogis have averred: our respiratory and nervous systems are linked, and what we do with the first has a direct effect on the work of the latter.

The human brain connects to the rest of the body via electrical signals. Nerve endings throughout connect to the spinal cord, which in turn connects to the brain, and vice versa: physical experiences are sent to the “control center”, which processes them and then sends back responses originally intended to keep us alive. For example, the sight of a tiger in an open field propelled hunter-gatherers to hide, bolt, or battle with the predator. This ‘fight-or-flight’ impulse allowed humans to avoid danger and reproduce, thereby ensuring survival of the species.

Scientists divide the workings of the nerve structures into two different systems, the sympathetic and parasympathetic. These control the body’s state of arousal, priming it to respond to danger or recover from that experience. The sympathetic nervous system revs up the body so that it can protect itself; the sympathetic nervous system slows it back down, allowing for rest and repair. Hormones such as cortisol are part and parcel of the way these structures work, and are neither good nor bad; while we usually don’t encounter large carnivores within the city limits, we do need to empower ourselves to give presentations, sprint across the street to avoid being hit by cars, and propose marriage to someone we love. Trouble occurs when the sympathetic nervous system is over-stimulated, and we walk around in a constant state of arousal. Without a balance between action and rest, the body “protects” itself in ways that cause damage over the long haul, such as an unneeded layer of fat!

Enter respiration, which can connect with the nervous system through the vagus nerve, which passes through the entire torso. Breathing is composed of inhalation and exhalation, and the length of each matters, When our in-breath is longer than our out-breath, several things begin to occur. Carbon dioxide builds up in the body, which puts us into a ‘fight-or-flight’ state. We begin to breathe faster, and our heart beats faster; if this continues without physical release, we may find ourselves into panic mode. However, if we then lengthen the exhalation, we remove the excess carbon dioxide, which alerts the vagus nerve that stress hormones are no longer needed by the body. Thus, our breathing acts like a signal, letting the muscles know whether to rouse or relax.

This can be powerful knowledge for those of us who suffer from anxiety or depression. We can practice breathing techniques that help us to relax, to focus, or to get ready to do battle. If something happens, we can use the length of our inhalations and exhalations to calm ourselves down afterwards. When meditating, we can focus on our breathing and discover how we are feeling physically even if we’re in an emotional state that causes us to lose touch with our bodies. Breathing can ground us; even in situations where asana isn’t possible, we can always excuse ourselves, go to the restroom, and take a moment to breathe ourselves back on track.

Yogic breathing exercises are generally not taught by scientists, and as such are often cloaked in mystical language. Pranayama isn’t just ritual, however – it’s an accepted way of working with the human body. We have more control over our physical well-being than we realize, and working with the breath can be every bit as important to our health as working with the body. Take these practices seriously!