Can anxiety cause physical symptoms?!

i have anxiety and panic about an irrational fear of no sleep. the fear is that i'm not going to be able to sleep and will eventually lose my mind from no sleep. now i know that isn't possible but apparently knowing that isn't enough to stop the anxiety. but one of the things that keeps me up and gives me the anxiety is that i get this terrible uncomfortable sensation on both sides of my neck when i'm really really tired. the worse i panic the worse it gets. it feels swollen, the skin all over my neck tightens up and gets really warm and i can't lay down because anything touching it (my skin bunching up on it when i lay down) makes it so uncomfortable that i can't sleep and it's almost painful. is it all in my head and caused by the anxiety????