I clench my teeth badly while sleeping. I often have a sore jaw in the morning because of it. It is caused by agitation or anxiety I think. When in a mixed state or very anxious I clench my fists a lot both during the day and night. I try to be mindful of my body and that helps me stop doing it, if only for a few minutes. It is slow going but I am making progress. I used to be completely unaware I was doing it.