Some of you know that I have been having migraines daily. Chris asked me if I had been wearing my nightguard. I have. But I thought back to when I bought it and the directions said most people go through this guard yearly...but some people need a new one sooner than that. Well, it turns out I am one of the strange ones. I bought a new one and used it last night. So far, no migraine today! Hurray!!! So, I guess I will need a new one every 3-4 months.