When I started with my PS1 I was coming off a month of very poor sleep. I was really exhausted and when I finally got the machine adjusted properly I had two nights of what felt like very deep sleep. In those two nights I only had periodic breathing a couple of times in the night and those times were associated with falling asleep.
Refreshed by those two nights, I now sleep lighter. I am now seeing PB more often.
Maybe the increased PB is a sign of progress? I certainly feel much more refreshed than I did a week ago.
Only wise people learn from them