What Causes Irregular Heart Beat During Sleep?

Hi, Iwas currently worried about the situation I have going on, every night I go to bed and drift off to sleep Ican hheary heart beating slower and slower and it eventually feels like my heart is about to stop, and all during it im experiencing a sleep paralysis type phase and I can t move, I finally jump up out of my bed and sit while my heart beats at its normal pace, this has been going on for the last past month and im getting worried that it might be something serious. I just want to understand why this is happening and if you have any good tips on stopping it.