Late night increase in AHI

The first couple of weeks of CPAP went really well for me. I was feeling great, lots of energy, sleeping more and more. The past week or so, though, for unknown or various reasons, I have been sleeping less and less well. Not due to the OSA so much, but rather some related and external factors, the first being my moron cat scratching the bed at 2:00 am! It seems like something has happened every night lately to keep me from getting a full nights sleep. One night I woke up coughing my lungs out, and it took a couple of hours to get settled back down from that. Another night I got a terrible sore on the side of my nose from the mask which woke me up and kept me up for a while. Another night, I set the humidifier up a couple notches to keep from coughing and it got cold enough to increase the condensation in the mask, which started leaking out and down my face.

Anyway, the true purpose of this post is not just to whine and pule, since I have found or will find solutions to most of these problems (except the moronic state of my cat) but to ask about something I have observed. Since I have been awakened most nights anyway, I have checked my numbers in the middle of the night and they are usually low, AHI about 3-5. Then I get back to sleep again and wake up, and check my numbers again. Almost always, they have jumped at least two points, to AHI of over 5-9. My machine only provides raw data, (which I learned how to access here)no way that I know of to see exactly when the events are occurring. I am just curious if it is "normal" or common for the number of AI and HI's to increase in the latter part of the night, and would welcome any input or hearing about similar experiances. Thanks!

In looking at my data, I notice that the first couple of hours are low, but things jump up later in the evening/morning.
I have chalked this up to being in REM sleep (where most of my episodes occurred during my sleep studies). I could be wrong, though.

This happens to me. Clusters of events later in the night. It's a good bet that these disrupt my REM sleep. That's why I try to keep everything as good as possible and side sleep, since back sleeping during REM is causes more apneas.

One way to check is to look at your sleep study and see if there is a distinct pattern of having apneas during REM, especially when laying on your back (supine). If so, it's an educated guess that this is what these are.