The actor plays a man who helps steal secrets from dreamers' minds in the new movie, and began to take a serious interest in the subconscious after he was cast by director Christopher Nolan.
But the star admits he still struggles with his ongoing studies - because he always forgets what he dreamed after waking up.
He tells Britain's Live From Studio Five, "It did make me think more about my own dreams. I don't really remember my dreams and it's something I want to be able to do. Having worked on Inception, I did a bit of reading about the science of what's going on in the brain (while dreaming). I learned it is a skill you can acquire.
"One day I hope to be able to have a lucid dream, which is when you know that you are dreaming while you are dreaming and you can maybe kind of take control of it a little bit. I haven't gotten there yet but I'm working on it."