One you bought from a store, or one made for your teeth? I have that problem (not so much anymore though) and I got one custom made by the dentist (not very expensive) and it helped alot. I actually haven't used it in years but keep it around just in case. When I wear mine, I basically CAN'T grind my teeth or clench my jaw---just isn't possible. (Tension headaches are the worst, especially because you feel like you could prevent them.)