Ihad severe teth grinding problems during my freshman yr of college. I got a sports mouthguard to start, but it caused horrendous drooling and I had to sleep with a towel on my pillow (good thing I was best friends with my roommates so they didn't tease me too much.). Itdid the trick for a while, but I emded up biting through it and eventually had to get one made by the dentist. It was a much different experience, as it was incredibly comfortable. I would start with one of the Boil Bite guards from Sports Authority or Dicks.
Sorry for the typos...my iPad keyboard is tricky!!