In this paper the author considers the state arising when a man perceives and remembers the information presented during night sleep (this educational method is called hypnopedia). On the basis of the analysis of hypnopedical researches' results it is proved, that a student forms the new kind of sleep — hypnopedical sleep (it appears on stages 1 and 2 of slow-wave sleep): this kind of sleep has new functions (perceptual and mnestic), new time borders (the appropriate conditioned reflexes of falling asleep and awakening on certain time and on presentation of the information are produced) and transformed neurophysiological basis (an alpha-rhythm appears). Hypnopedical sleep as altered state of consciousness can be considered as analogue of the higher mental function because of it has social origin, are voluntary (it is formed not spontaneously, but intensionaly and directedly) and are mediated by such psycholgical tools as preliminary created readiness to perceive and memorize the information.