Why does it feel like bugs are crawling on me?

Ok i really need some help here i thought i was crazy for a second! every time i lay down to go to bed it always feels like something is crawling on me this has happened for years and it causes me not to have any sleep most of the time and yes i don't like bugs and Iam scared of them but sometime iam not even thinking about them when iam going to sleep and i once or twice had a bug crawling on me but i think thats happend to everyone and i've already gottin over that