Meaning of slow-wave sleep

slow'-wave' sleep"

Pronunciation: (slō'wāv'), [key]
— Physiol. Physiol.
  1. a recurrent period of deep sleep, typically totaling five or six hours a night, distinguished by the presence of slow brain waves and by very little dreaming. Also calledCf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.