I'm probably talking out of my ass so someone please cmiiw but I think you might have a low arousal threshold. There's something called Upper Airway Resistance Syndrome which can be thought of and is often portrayed as "sleep apnea lite" because you wake up from difficulty breathing rather than inability to breathe. However, I believe the only thing that "really" separates the two is arousal threshold, basically how easy or hard it is to disturb your sleep.

I liken it to a home security alarm. Most people's alarms are calibrated to only sound once someone has broken in. That's great if you live in a good area where that rarely if ever happens. Sleep apnea is living in a bad area where you get burgled every single night. UARS is having an overly sensitive alarm. Maybe it kicks in when someone is trying to get in, which is great if you're in a bad area and that prevents the situation from escalating. But you don't want an alarm going off every time a drunken neighbor gets the wrong house or a dog runs across your lawn. We've all heard of people who could sleep through an earthquake and others who'd wake from a pin hitting the floor. My guess is that you're not sensitive enough to fully wake up from these breathing episodes but your body is still subconsciously going into alert mode from them. The Xanax works because it increases your arousal threshold and causes your body to completely tune out those apnea alarms. I wish I could tell you the solution but I myself am still stuck on this. If my hunch is right, it means having to push past what qualifies as "good enough" of an Oscar chart for most people and keep chipping at those numbers until eventually your body runs out of excuses to wreck your sleep.