The tooth grinding is called bruxism. Eventually it can lead to loose teeth, worn or broken teeth, and/or painful jaw popping called TMJ. It's caused by stress and taking certain medications, like SSRIs (surprise!). To help fix the problem: talk to a doctor about reducing stress or medications, buy a "night mouth guard," or visit a dentist who will make an expensive custom guard.
I think people are right-you HAVE to be grinding your teeth in your sleep. You need to see a dentist-they can fit you with a gadget to wear at nite to stop that. Years of grinding your teeth will ruin them.