As somebody who had severe OSA for several years and didn't know it, a couple of points. 1) For onlookers, especially with a chronic condition, this is symptom

As somebody who had severe OSA for several years and didn't know it, a couple of points. 1) For onlookers, especially with a chronic condition, this is symptom-free. You might just appear to be more cranky, or forgetful -- normal signs of aging. 2) Even for the person experiencing it, chronic hypoxia doesn't necessarily "feel" like anything. I was regularly getting my blood oxygen down into the upper 60s and as long as I had enormous amounts of caffeine I was good to go. Over time, especially after getting a CPAP, I realized to look for symptoms: skipping over words in the middle of a sentence and guessing incorrectly what they were, a more difficult time focusing (both mentally and with my eyes), and so on. Hypoxia in pilots has been studied over and over again, and no matter how hard you train, it still sneaks up on people and takes over. Scary stuff. 3)You do not necessarily experience an overnight resurrection when this condition is fixed. Many do, but many do not. Sometimes you just realize that you're now entering a long phase of recovery. I can't adequately describe the emotional transition that goes with recognizing hypoxia and getting it fixed. There's a sense of joy, sure, but also a sense of fear: you realize just how close to death you were living, and how dependent you now are on a machine (or drug or whatnot). Living low on oxygen is a frightening and life-changing experience. Once I realized I was basically strangling myself every night -- passing out and then coming to over and over again just enough to be able to breathe again -- it dramatically changed my image of my body not letting me down. Hypoxia teaches that you can be severely broken in ways that you are not able to discern. Not fun.