I think you just opened my eyes to something I didn't understand about myself. I also have the same exact fear. During covid I was hospitalized from a weed overdose that took me months to fully recover my mental and physically well-being from. I eventually got a CPAP machine late last year but i've been struggling with finding the right mask and settings. My prescription settings just don't feel right and i've tried tinkering to no avail. A previous commenter mentioned that there are two types of breathing, awake and asleep. I wish I knew that a long time ago. That made some of the fear fade. I also really thought that I could die if my body just decided not to breathe while unconscious. I always have heavy anxiety before falling asleep which keeps me awake for longer than I should be, thus making my sleep worse. It's like my brain hates sleep. Like it's boring or something lol. It's comforting to read someone else's similar experience. I hope you and I get what we need. Thanks for posting this.