Last two out of the last three nights i have woken from my sleep in a huge sweat with my body feeling really cold and breathing really heavy, my heart thumping quickly and loud enough for me to hear or maybe just feel comfortably, each time this has been followed by my heart seeming to stop for a good 5 or 6 seconds making me feel how i can only really describe as numb, then it seems to kick back into a fast beat and slowly settles back to normal once i've got up. This has happened each time a total of five times over the two nights. I've also started having heart papiltations whenever i'm lying lying down, i smoke about 10-12 cigarettes a day and don't drink much caffeine, and have had no problems like this in the past and take no medication.