I did this for years and it would make me incapacitated for anywhere from an hour to eight hours. It happened upon waking but also in the middle of a family occasion or a movie, or while watching TV. I was finally prescribed Xanax which helped within a half hour. It was therapy and finding the root cause that finally helped me conquer this problem. And once I realized what it was, the fear that caused the panic left me. I have Xanax on hand but haven’t had need for it in quite some time. For me it was psychological but I’m sure it’s not that for everyone.