Mine is a pretty high pressure, and a full face mask. The high pressure means the mask has to be strapped pretty tight. It also makes it tough to get into a regular breathing pattern, making just the act of breathing a major chore. You can't talk, or cough. You have to stay in certain positions to prevent the air from leaking out. The air echoes down the tube. I was a stomach sleeper before, which is impossible with the mask, so had to learn to sleep on my side. Every now and then, I do skip the mask occasionally, and it's words can't explain how much better it feels to sleep "normally". So I can see why a lot of people skip it.