I am new and need to know..........too. So if someone could shed some light on this for me...............I have been, for about three years, on occassion, waking up in the middle of the night, usually 2 hours after falling asleep, with a rapid heart beat that usually is about 115 beats sometimes with the feeling of nervousness, sometimes not, and the general feeling of not feeling good. No chest pains -just feel hot, blood pressure rises to high numbers and it scares me terribly. I also noticed that I burp alot too at this time. I do have stomach acid problems but am wondering if this is all anxiety. This only happens in the middle of the night. It has been gone for three months and came back in the past week. What seems to relieve me is 2.5 mg of xanax or valium. I want to think this is panic disorder related rather than heart. What do you think? Thanks for your replies.