Dream simulator

This is a horror, romance, sci-fi story based upon horror movies, violent videos games and my very own creativity. We follow a young university student, who has a sleeping disorder. She constantly gets haunted by her very vivid nightmares. Yet a mysterious letter arrives for her from a scirentist testing his new experiment called the "dream simulator". It takes your nightmares away and resplaces them with good memories. All you have to do is think of the worst dream you've ever had and it will erase it from your memory. What could possibly go wrong?