The idea behind "Inception" was first developed over nine years before it was released. But, there is also another anime film just like it called Paprika (2006 film). After the 2002 completion of "Insomnia", Nolan wrote an 80-page treatment for a horror movie envisioning "dream-stealers", presenting the idea to Warner Bros. based on ideas of lucid dreaming and dream incubation. 