Breathing re-education can improve sleep quality and bodily oxygenation, by optimising breathing during wakefulness and during sleep. Myofunctional therapy corrects the oral rest posture to support the airway, and strengthens and repatterns the muscles around the airway to increase tone, thus reducing the likelyhood of snoring and full airway obstruction (apnea).
Further reading and research can be found here:
https://pubmed.ncbi.nlm.nih.gov/31940122/
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://buteyko.info/wp-content/uploads/2017/12/Sleep_Apnoea_and_Breathing_Retraining_Report_May_2012.pdf