yes, and it definitely reduced the headache, pain in my neck. But I HATE the thing. Lots of reasons. I rarely wear it, only when I've been having regular tension headaches. Then I get the damn thing out and wear it for a few nights until the muscles unclench a little. The problem is, you will still clench/grind your teeth even with a mouthpiece, so you need to get to the bottom of the problem. The good thing about a mouthpiece is, even though you still clench/grind, it takes pressure off the roots of the teeth. Clenching can cause the tooth root to be avascular, the lack of blood flow can make the teeth loosen and weak. It's probably important that you get and wear one for now--even though I don't take my own advice. HA!
Ideas? Well, some say that grinding your teeth is a psycho-somatic result of keeping your mouth shut and not saying the things you need to say. Others claim that is it mal-adjustment in the cranial bones--especially of the mandible. In that case, cranio-sacral work from a trained and certified LMT might help. It won't be covered by insurance though, and a mouthpiece might.
Personally, I think it is # 1. I started grinding my teeth when I started being unhappy with the Org. Once I made the decision to never go back, it lessened up. But I've noticed when I have dealings with my Dub family, it gets worse again.
Good luck, save your teeth.
Odrade