u/Dodgingdebris

I bought the reviv 3 and have been wearing it nightly. Once I fall asleep my mouth will not stay closed and I always wake up in the middle of the night with an extremely dry mouth and tongue, and usually the mouthguard becomes loose at that point. This morning When I spit it was brown. I've never had brown spit before... I want to keep using this thing but does it get better at any point?? How long do these take to get used to?