This seriously happens to me every night, heart racing for what seems like NO reason! I understand how nerve wracking and frustrating it can be, something that makes me feel better and slow down my heart a little is to lay flat on my back with my hands folded on my stomach and take in a really deep breath with my nose and then slowly breathe out through my mouth.. If you do it for a few minutes it calms you down. Hope it works for you, and even though it may not seem it- you will be fine
