Is an overactive imagination recurring?

All through my childhood, I used think there was a snake in my bed. It got to the point where my mom moved my bed into her room. Not, I'm 16 and for the past three nights I've dreamt about a snake in my bed. It's almost like I can feel it. I used to imagine spiders running down my walls, and balloons. Okay, don't make any jokes about drugs. Isn't an overactive imagination something you only have as a child?