I've had a Resmed airsense 10 for about 7 years or so, and it really changed my life from waking up with headaches and being dangerously tired all day. I now have the air sense 11, and I am waking up with headaches again despite setting it up the same way as the air sense 10 settings were set all along. One thing I do notice is that when I would stop breathing intentionally on the air sense 10, the machine would push back at me an increasingly more powerful volume of air, even pulsing, to the point where even during my sleep I would recognize that I had to do something that would start breathing. With this new machine, the air sense 11, if I hold my breath the machine just continues blowing at me like a regular fan at the same continuous pace and pressure. Is there some sort of setting that I'm supposed to change that I have not changed? Of course if I go into and apnea episode and the machine does not wake me up to remind me by pulsing, or pushing harder, I will not be reminded to breathe and perhaps that is causing my headaches and tiredness. Can you guys and gals help me figure out what is wrong? Is it just that I set it incorrectly? Or my machine is defective? I would assume that every machine set to auto set should perform in this way. Thank you very much for your help.