my best pal had a mouth guard made by the dentist for a severe case like this. She was in real danger of damaging her teeth, as well as chewing the insdie of her cheeks etc. She was waking up with very bad headaches and feeling virtually unslept. She changed jobs at the start of this year and you know what? She's not used her mouth guard once since. You can stop the side affects by use of a guard, but maybe it's worth a look at what (if anything) may be causing such night time tension? In my pals case it was work related stress.