I wake up in the middle of the night, my heart is racing, I get a tingling sensation that waves through my body and i alway have a bowel movement after this happens. I try to take deep breathes while it is happening but it's hard to breath deep when your heart is racing. The wave of tingling will come about three to four times during an episode. Once my heart slows down I have a bowel movement and things seem to settle down. I am not anxious before this starts but I am once it starts. What can cause this. I've been told anxiety attach but know that is not the cause but is a result once an episode starts.