Nina...here's a link you may want to check out...
http://content.health.msn.com/conten.../30/1728_70608
As for grinding teeth, my son does it while he sleeps, & both my daughter and myself do it when we are pissed and releasing stress. Sometimes I can almost feel my teeth crack. My husband calls us 'Crazy Tooth' when we are freakin' mad.
As for what causes it during sleep......don't know but my mother's (italian) book of old wives' remedies says that it's tapeworms....cure that and the grinding goes away....don't know if it works.