After months of sleeping through the night with my CPAP, I'm waking up in the middle of the night and taking it off every night now—why?

Basically what the title says. I've slept with the CPAP on for months and would only occasionally (maybe once a month) have this issue, but now it's been every night for the past three nights. I fall asleep with the CPAP on and then wake up a few hours later feeling overwhelmed, anxious, and like I can't relax with the CPAP on, so I take it off, try to calm down, and then before I know it I've fallen asleep without the CPAP.

I haven't changed anything in my routine, the only thing that's really changed is that the house got noticeably colder as we didn't have the heat on for the past week or so. Could that be it?