"She tried to will herself to sleep but realized she was listening intently, listening to the room. She lay in a kind of timeless drift, a mindwork spiral, carried on half-formed thoughts. She passed into a false sleep and then was listening again. She opened her eyes. The clock read four-thirty."
- Don Delillo, from "The Ivory Acrobat"
It's a feeling with which I'm intimately familiar. Never associated it with Delillo-style paranoia before, but it makes perfect sense.