To Fall Asleep...

The English expression “to fall asleep” is apt because the transition between waking and sleeping is a gradual drop from one state of being into another, a giving up of full self-consciousness for unconsciousness or for the altered consciousness of dreams. Except in cases of exhaustion or with the aid of drugs, the movement from one world to another is not instantaneous; it takes a little time. Full waking self-consciousness begins to loosen and unravel.

— Siri Hustvedt, in the NYT article All-Nighters: Failing to Fall (via The Literary Piano)