What Is Sleep?
I am convinced that during bouts of insomnia I have sometimes slept without knowing it. The thoughts of waking seem to mingle with thoughts that may be part of sleep. Has the clock moved too quickly? Did I doze off? Some years ago in a rented house in Vermont, I couldn’t sleep and lay awake listening to the sounds of mice in the walls, bears that sounded like owls calling to each other in the woods and the wind in the trees. I then dreamed I was lying awake on the very bed where in fact I was sleeping, but someone had broken into the house. Because the room where I actually was and the room I dreamed were identical, the threshold between waking and sleeping had blurred and, when I woke up, I thought I heard the burglar moving around downstairs. It was a frightening experience, a temporary loss of the boundaries between waking experience and the illusions of dreams.