You could place an object on the other side of your room or in another room entirely. Make it a mission to fetch it when you do wake up, that way you won't forget or will at least have evidence that you were up. Be sure to do a reality check when you do pick it up as you might dream of fetching it! Some extra water before will also ensure that you can't fall asleep again without leaving the room. If you want to try DEILD without moving much, you can intend to move something on your bedside table.