I don't have the answer to this, all I know is it keeps happening to me but on top of this I feel like my brain is being twisted inside of my skull.. something really weird is happening and I need to have a scan of some kind to figure it out..
I'll have this heavy feeling in my brain that I have to get up and wait till it's gone until I go back to bed. But yeah my heart will speed up alot, I can hear it in my ears.. and then just stop, and that freaks me out
I do feel my heart stop during the sleep. Amazingly, our body can wake us up and I wait for the beats to come. The strange is, I got the pacemaker but it still let my heart "pause" for 3.2sec without a pacing. Normally, when the beats come, it is strong and big dump. Sometimes I got 6 or 7 times during the night sleep. I was too tired and not even bother to wait for the beats come. I just went back to sleep straight away.
Ask your doctor to let you wear a holter monitor. If you didn't catch the "pause" during 24 hours then ask for the longer period one. It's good to catch the episode that you experiencing abnormally. It tells you what are those. Life threatening or not. The doctor then can base on that and refer you to the specialist. From there, you'll receive the proper treatment.
Take care and good luck.
found it, its called sleep paralysis strangely enough.
http://www.wikihow.com/Cope-with-Sleep-Paralysis
I believe there is a sleeping disorder where people wake up paralysed. I can't remember the name of it but there are quite a number of sufferers.