Yeah, I can't relate in the same way but similar. I have vagal syndrome: if I see blood or if I am in a lot of pain, then I pass out because my heart slows down. I get dizzy and I get this really bad feeling in my throat.. and if I don't sit down I'll black out and hit the floor.
My brother had donated blood and he has the same thing as me and he was out for like twenty minutes.. freaked the people out.