hi.\rwelcome to healthcare magic,\ri understood your question,\rthat you are perceiving your own heartbeat during sleep time.\rThese perception of own heartbeat during sleeptime is a normal phenomenon, it most commonly occurs in thin individuals , when it become silent atmosphere.\rAs your ECG,TMT were normal . noneed to worry.\rIf you are having feeling of fast heart beat, missed beats\rassociated with symptoms of giddiness, loss of consciousness you should immediatly consult a doctor.\rthank you\rbest wishes.