Hi Ray,

I do not know about the yawning issue, but know that the dry mouth issue was big for me as a mouth breather. I have adjusted the humidifier to a 4 setting and that helped (for mine I turned the knob to the right one click after the machine started)...it is not uncommon for the humidifying chamber to stop working either and I had to replace mine after only a few months...I noticed that the little metal disc on the bottom of the water reservoir was not warm and the water level never went down...My tank will barely last two nights so I know it is working...it is all going to be okay...for me I've just had to keep reminding myself to not let these maladies define who I am...Take care, Reid

mouth breathing with any nose only mask often causes a dry mouth, regardless of humidifier setting

tape the mouth, a chinstrap wont stop it

That is why I went with a Quattro XL mask that covers nose and mouth...I could not stand the nose only option, and it is useless for apnea if you open your mouth...though I know my wife would like to add tape to my mouth most of the time, I could not stomach that option. It is a simple mask to use and is effective with my mouth open or shut.

You are lucky. When I tried the mask that covers mouth and nose, my dry mouth was much worse. I'm now just using nose pillows, which I do like a lot more than all the other masks I tried. I still have occasional dry mouth issues, and occasionally do use the chin strap if I feel it's necessary.. The products for dry mouth seem to work for me.

at higher pressures, with no humidifier, the saliva is partly evaporated