Insomnia (original) Stephen King

Ralph Roberts has a problem: he isn't sleeping so well these days. In fact, he's hardly sleeping at all. Each morning, the news conveyed by the bedside clock is a little worse: 3:15...3:02...2:45...2:15. The books call it "premature waking"; Ralph, who is still learning to be a widower, calls it a season in hell. He's begun to notice a strangeness in his familiar surroundings, to experience visual phenomena that he can't quite believe are hallucinations. Soon, Ralph thinks, he won't be sleeping at all, and what then?