Hi, cheeterky, my name's Camylou. Hey, you know what? That happens to me quite a lot--waking up with a rapid heartbeat. When my bladder wakes up in the wee hours of the morning, I was used to just jumping right out of bed. But no more--that's a mistake. I find myself dizzy, swaying, out of breath, and sometimes sitting on the bathroom floor with my heart pounding, waiting for it to calm down. I'm on several meds, three for depression, anxiety/panic attacks and bipolar, so I don't know if any of those cause this. Could be I have an irregular heartbeat, it's shown up before but under circumstances like an allergic reaction. I'd check through your meds and see if any of them can give you a rapid heartbeat, and maybe a trip to the doctor too just to talk things out with him/her. I'll be keeping you in my thoughts, my new friend.
Camylou