When I have to lie down to nap or sleep, I am overly aware of my heart. It scares me and it feels very fast or strong. But when I take my HR it is always within normal range 55-85 (unless I panic, which sends me 90 or above 100). 

Does anyone else feel like their heart is fast but it isn't?

My cardiologist says I'm fine and just sensitive but idk what that means. 

Is this a brain issue...?