So my update is simply that I've been getting to bed / sleep before 10:30pm every night since my previous update, and the CPAP machine reports at least 8 hours of use every day. But as I wrote to LadyShadow, I've been waking up frequently.

One night's waking was particularly memorable. I was dreaming that I was walking a long distance in some city while carrying a heavy object as one would carry a full basket of laundry. As I walked, I kept telling myself that I should've parked closer. But then I reasoned that I could do this -- it's good exercise. I was getting out of breath when I woke up. That, BTW, is a classic type of sleep apnea dream -- I really was out of breath because I wasn't breathing!