Sleep-learning or sleep-teaching (also known as hypnopædia or hypnopedia) is an attempt to convey information to a sleeping person, typically by playing a sound recording to them while they sleep. Although sleep is considered an important period for memory consolidation, scientific research has concluded that sleep-learning is not possible. It appears frequently in fiction.

History

In 1927, Alois Benjamin Saliger invented the Psycho-Phone for sleep learning, stating: "It has been proven that natural sleep is identical with hypnotic sleep and that during natural sleep the unconscious mind is most receptive to suggestions." Since the electroencephalography studies by Charles W. Simon and William H. Emmons in 1956, learning by sleep has not been taken seriously. The researchers concluded that learning during sleep was "impractical and probably impossible". They reported that stimulus material presented during sleep was not recalled later when the subject awoke, unless alpha wave activity occurred at the same time the stimulus material was given.

In fiction

Sleep-learning is found in influential science fiction and other literature. The following examples are listed chronologically by publication or original air date, when known.