Are you always dreaming?

Have you ever had those thoughts, where you think you're dreaming? Or, let me put it better this way. Today, in the shower, I was just thinking. What if my life, everything in it, all the events, my friends, anything that ever happened, was all in my head. Like, none of it ever existed, & I just thought it all up. I think about that a lot. Sometimes, I feel so light headed, that I think I'm a puppet or something. Then I thought that since everything was in my head, what if in reality, I was some insane person who couldn't even handle eating, or something? I'm weird. Hopefully, all of this isn't in my head, & I'm alive & fully functional.