I got tested years ago after a series of visits to my GP, who sent me for testing for SA after feeling tired at work all the time.
I wore the kit overnight that recorded my sleep pattern and they gave me the results as mild SA and wasn’t a risk to driving. Turns out from the results it worked out that I sleep on my side a lot, my airway was reduced because I had large pillows and I snored and had a girlfriend at the time. She left me about 6 years ago and I never had any SA symptoms since.
Long story, short turns out she was kicking me at night when I was snoring, hence never getting any REM sleep and wondering why my back and legs ached every morning. 