Want to improve your health on a truly deep level? The practice of yoga—including pranayama (breath control) and meditation—has been proven to improve the function of the entire nervous system, which controls all of your internal functions and physical movements.

Yoga exerts this power by calming down the two dueling parts of the nervous system: sympathetic and parasympathetic. The first is famous for the “fight-or-flight” response, which causes the body to spring into action and prepare for physical and mental activity. The second causes the “rest-and-digest” response, a general slowdown in the body’s functions in order to conserve energy.

These two sides originate in two different locations within the central nervous system. Parasympathetic nerves emerge in the brain and brainstem, and sympathetic nerves arise from the spinal cord. The most powerful, natural way to modulate both of these is through respiration—pranayama, or breathing, in other words.

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Yoga imparts a calming effect because it basically undoes the sympathetic nervous system’s quick, involuntary response to danger or stressful situations. A regular yoga practice has been shown to improve digestion; strengthen the immune system; and reduce the risk of hypertension, asthma, and stress-induced psychological disorders like anxiety.

It does this, practitioners have long theorized, through a unique blend of science and spirituality.