Breathing through your mouth, snoring, yawning, waking up to a dry mouth are all signs that you're overbreathing. While these signs are almost always neglected and ignored, it is important to note that it could mean something more severe than it appears.
Usually, we breathe in oxygen (O2) and release carbon dioxide (CO2). But when we breathe abnormally, CO2 levels build up in our body leading to a drop in blood pH levels.
Almost always, we give credit to oxygen for regulating our breathing, however, CO2 has a vital role to play in this entire process. CO2 levels are the main influence. A rise in CO2 levels in the body is what urges us to breathe, rather than a lack of oxygen. That said, the more intolerant you are to CO2 levels in your body, the sooner you will feel the need to breathe. Mouth breathing can increase your sensitivity towards CO2, making you breathe faster, which is why experts and physicians always recommend nasal breathing.