I freak out when I'm alone in a dark room with a mirror?

I always feel like I can see a shape in the mirror...then I blink and focus and it's normal. Sometimes I get so paranoid that I hyperventalate and run out of the room as fast as possible, my heart racing, feeling like I'll die if I don't get out of there. And then Other nights I'll be normal. Am I paranoid, or do other people feel like this?