My newest fear/fixation is being afraid to fall asleep now because I am convinced I'm going to die in my sleep.

Ever since my er visit and dealing with the post migraine fatigue/nausea and vagus nerve dysfunction causing trouble I have somehow convinced myself that I will die in my sleep. I'm currently overanalyzing every little thing my body does at the moment. Breathing feels shallow? Here comes death. Heart rate jumps up? Here comes death. Ugh why can't I just be normal