I have difficulty telling dreams from reality, why?

I've always had very vivid dreams and on occasion I've had issues telling them from reality. For the past few months this problem has gotten worse and I've actually had to ask people on regular occasions if something happened or not. What I want to know is what is causing this and if there's a way to make it stop. By the way, don't get me wrong I love my dreams, it's just becoming an issue.