I'm a cheek biter-not hard biting, more like nervous habit biting. My dentist has implied that this is related to the jaw grinding I do in my sleep. I try to chew a lot of gum to avoid chomping on my cheek and to hopefully tire out my jaw muscles so I don't grind so much in my sleep.
Hmmmmm maybe that's it. I grind my teeth big time in my sleep. I had to get a guard made just for that and it also caused me to have TMJ. I don't chew a lot of gum because that also causes TMJ for me.. Just didn't realize that I might chew my gums from grinding my teeth!