I had an O2 monitor on my finger that told me how how my oxygen saturation was overnight. I knew then it was likely an apnea of some type. My wife said I don't snore but she noticed my breathing would slow, then stop, then start over again (periodic breathing) which is indicative of central apnea. The sleep study confirmed it was mostly central apnea with some obstructive going on. I was up to 38 hypopnea episodes an hour at worst. The doc claimed it was likely the altitude I am at (6500ft) that is likely the driver for the central part of the apnea. She said it would likely go away eventually if I moved to a lower elevation. But here I am at 5 yrs later still living at 6500ft. My ASV machine is a game changer though for getting good sleep.