Laying down flat, especially back, but sides too... getting out of breath walking and talking at the same time. Those were the first & still primary culprits.
I also had horrible headaches which would wake me in the night, and just getting up and breathing deeply in and out for a bit would make them go away. I did not and do not snore (or so I'm told) so, sleep apnea can happen without snoring or a feeling of obstruction.
With me its my MIP and MEP that is particularly low, MEP at about 20% and MIP at 40%. FVC fluctuates quite a bit, it was at 80% last week for clinic.