Mothers have always been known to tell their children to take a long, deep breathe to relax or to stay calm. The New York Times reports on the science behind why this may be true. Here’s my comment to the New York Times in response to the article:
There are two proven benefits to deep breathing exercises, especially with good nasal breathing:
1. The nose makes a gas (nitric oxide) which dilates blood vessels. When inhaled into the lungs, it can increase oxygen uptake by up to 10-20%. Mouth breathing will therefore cause you to take more shallow breaths and breathe slightly faster, leading to slight hyperventilation. This will blow off carbon dioxide, which raises your blood pH, making your red blood cells hold on to oxygen more tightly, and also makes your nervous system more hypersensitive.
2. Breathing in stimulates your parasympathetic nervous system (vagus nerve), whereas breathing out stimulates your sympathetic nervous system. In the relaxing breath in yoga, inhalation is through the nose (with the benefits of nitric oxide) but exhalation is out the mouth, taking twice as long. During slow exhalation, you’ll see your heart rate dropping slowly, and you’ll feel calmer.
Unfortunately, many people can’t breathe properly through the nose due to a deviated nasal septum, which is aggravated by dental crowding and a high arched hard palate. The septum buckles to one side since the roof of your mouth doesn’t drop properly, and this also leads to crooked teeth. This is also why if you can’t breathe well through your nose, it’s also likely that you won’t be able to sleep on your back (smaller oral cavity volume).