Well, you are right that the breathing techniques don't work when sleeping. With just APAP, pressure range 8-17, I still had SpO2 events below 80%. Since going to Bipap, with pressure 10-19, plus 1l/h 90% O2, my SpO2 has improved to average 92-93% with no events below 85%, (rarely below 88%), so it has helped.
Diagnosed January 2017. I am 73 yo, active (hiking, gym, Tai Chi and Aikido), but I have COPD, which aggravates the situation. My main sleeping problem was not Obstructive apneas, but hypopneas. I learned to "belly breath" from pulmonary rehab, and it is also taught in Tai Chi and Aikido. When I fall asleep, my breathing becomes shallow, and my SpO2 tanks. Have switched to Bipap which helps a lot, and recently started adding just a little O2 to the CPAP hose and now my SpO2 rarely drops below 88% at night. (Runs 94-98% during the day. ). Still working on getting ideal settings to improve SpO2 at night, but is sure a lot better than the precipitous drops I had before.
I got my Phillips Dreamstation Auto on Amazon, brand new, for about the same price (<$400).
I find one of the nasal sprays like Nasocort helps a lot.
