Sooner or later in your experience with yoga, you will see or hear OM, which is essentially the universal vibration, a sacred syllable said to permeate everyone and everything. The sound of OM is so important to Hindus and Buddhists that many mantras begin and/or end with the syllable.
Sometimes, you might see OM written as AUM, which is a more phonetic spelling because the syllable is actually three audible parts: A-U-M.
One need not be Hindu, Buddhist, or any permutation thereof in order to realize the benefits of chanting the sound of OM because in and of itself, OM is not a “religious” word. In fact, it’s useful if a person doesn’t have any preconceived notions about the etymology of the sound. Here in Indiana, OM isn’t a usual part of speech, so if one were to choose it as a personal mantra, repeating it wouldn’t trigger thoughts as words in English might.
I present yoga as the art and science of self-regulation. Therefore, I won’t ramble on about my personal metaphysical experiences with mantra practice. I won’t even go into the bliss and the insight gained through chanting the mantra OM.
What I will say is that chanting helps to induce a peaceful, calm state because it involves breath work (pranayama) and vibration in the body. By chanting, or singing or whatever you want to do, you have to focus on the mechanics of the exhalation.
As you control the speed and depth of your exhalation, you elongate the breath going out. As your vocal cords vibrate and you exhale as you sing/say/chant “OM,” you stimulate the Vagus Nerve in a way which signals the Parasympathetic nervous system to kick on. In other words, the stress response is turned off and the body is able to relax, heal and metabolize.