Insomnia is a 1994 horror/fantasy novel by American writer Stephen King. It follows retired widower Ralph Roberts whose increasing insomnia allows him to perceive auras and other hidden things, leading him to join a conflict between the forces of the Purpose and the Random. Like It and Dreamcatcher, the story is set in the fictional town of Derry, Maine. It includes connections to other Stephen King stories, particularly his novel series The Dark Tower.