What can cause u to get dizzy like u r on a ship at sea and it only happens when u r laying down and should i be worried about it?

Is it positional?: When you say "get dizzy...and it only happens when u r laying down" do you mean that the feeling comes on when you are lying down from either a seated or standing position? Does it also happen when getting up from a lying position? Sounds like BPPV or "benign paroxysmal positional vertigo." You should touch base with a neurologist to help you.