I was able to fall asleep in the mouth guard at least three times (as some of you know, I wake up from hunger in the middle of the night and have to eat, and although typically it happens once a night, this past night it happened twice). I felt some discomfort when I woke up, each time, but that is OK. The important part is that I was able to fall asleep and stay asleep for several hours long stretches at a time.