Sounds very strange to me. I haven't seen that. Do you have a "count up" timer? I have an inexpensive Polder timer I bought on Amazon which has a "count up" mode as well as the traditional "count down." If you have something like that you could try starting it when you start the machine. Any history...

I can think of a couple possibilities: Might you have woken up in the middle of the night and been up for a while? If you sleep 3 hours, take your mask off for 2 minutes to use the bathroom or 30 minutes to have a snack and then put it back on and sleep 2 more, the S9 will add those 2 big chunks of ...

I think I'm also relatively lucky. (But for any people new to cpap or thinking about it - you may be, too!) The night of my second sleep study - when I tried on masks and was titrated - I think I slept about 5 hours (I'll get to see the results next week) and already felt better than a "normal" nigh...