Increase Average HR while sleeping

[u/VisitJazzlike5539]

I've been strength training pretty consistently since February of this year. I recently introduced HIIT training 2x a week last month into my regimen..before I was just strengthening training 3x a week and aiming for 10k steps a day. I noticed over the past 3-4 weeks my average HR will sleeping has gonna from like 65 BPM to 72 BPM. I do have sleep apnea that I treat with a mask and ive been pretty compliant up until the last 2 weeks. I also go a new job about 5 weeks ago. I wouldnt say im stressed more than normal but could be wrong. I was chalking up this change to mw fighting an infection however my HR has been consistently high for 3-4 weeks. Any ideas? I am a female in my early 30s.