Nasal Breathing

The diaphragm (your breathing muscle) reacts differently when breathing through the nose versus breathing through the mouth. When breathing through the mouth (which is easier) only the intercostal muscles (around the upper ribs) are activated which expand the sides of the lungs, and the whole lung is not engaged.  Nasal breathing activates the diaphragm to expand the lung from the bottom employing the entire lung.  It requires greater effort to pull the air through all the apparatus inside the nose.   

Nasal breathing is more efficient than mouth breathing because more oxygen is extracted from the lower lung.  Plus, nitric oxide is added to the air coming into the lungs through the nose which enables dilation of both the bronchi and the blood vessels which enhances O2 & CO2 exchange.  This results in a better distribution of blood throughout the lungs, and thus gas diffusion.  This also results in more O2 flowing into the rest of the body.

Studies have shown that with mouth taping at night apnea occurs less frequently (snoring  and dry mouth too) 

Mouth Taping Study

https://pmc.ncbi.nlm.nih.gov/articles/PMC9498537/

Healthcare (Basel) . 2022 Sep 13;10(9):1755. doi: 10.3390/healthcare10091755 

The Impact of Mouth-Taping in Mouth-Breathers with Mild Obstructive Sleep Apnea: A Preliminary Study    (Sleep position did not matter in this study.)  They concluded.... 

“Our study provided a simple and effective treatment modality using 3M mouth tape for mild OSA (Obstructive Sleep Apnea) patients with open-mouth-breathing.  The AHI (Apnea Hypopnea Index) and SI were reduced by nearly half after mouth taping during sleep; the more severe the baseline AHI and SI the greater the improvement after mouth taping. For mild OSA mouth-breathers, mouth-taping could be an alternative treatment before CPAP therapy or surgical intervention are tried.”