I've used my CPAP every night since starting therapy in early June, and i keep my mask on faithfully for 6-7 hours per night. I sleep on my side all night, usually. After a couple of rocky weeks at the beginning, my AHIs are now consistently under 5.0, usually between 3.0-4.5.
One thing puzzles me, however. Very often my 1st session, which is typically 4-5 hours, has dramatically better results than my shorter 2nd session and -- when I have more than 2 sessions -- my even shorter 3rd session.
Most of my AHI events comprise CAs, with very few hypopneas, and even fewer, if any, OSAs and RERAs. What happens is that I frequently experience a disproportionate number of closely-bunched CAs in the early morning after I've gotten up to use the bathroom and then go back to bed. For example, attached is a Sleepyhead screenshot of last night, showing the difference in results between my 1st session (5 hr 20 min) and my 2nd session (27 min). The AHI for my 1st session was 1.90, but with the 27 min 2nd session factored in, the AHI jumps to 3.90, twice what it was previously. The cause was 1 hypopnea and a cluster of 10 CAs in the short 2nd session.
This pattern is very common for me -- good therapy results for most of the night, then a short period in early morning with lots of CAs, resulting in a passable, but decidedly mediocre, overall AHI result.
Any thoughts on what's going on here, and what, if anything, I can do about it?