Sleep-learning

Sleep-learning (also known as sleep-teaching, hypnopædia, or hypnopedia) is an attempt to convey information to a sleeping person, typically by playing a sound recording to them while they sleep. Research on this has been inconclusive. Some early studies tended to discredit the technique's effectiveness, while others have found that the brain indeed reacts to stimuli and processes them while we are asleep.

History

In 1927, Alois Benjamin Saliger invented the Psycho-Phone for sleep learning, stating that "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. Since alpha activity during sleep indicates the subject is about to awake, the researchers felt that any learning occurred in a waking state.

Sleep and learning

Many competing theories have been made to discover the possible connections between sleep and learning in humans. Research indicates that sleep does more than allow the brain to rest. It also aids in the consolidation of long-term memories. REM sleep and slow-wave sleep play different roles in memory consolidation. REM is associated with the consolidation of nondeclarative (implicit) memories. An example of a nondeclarative memory would be a task that we can do without consciously thinking about it, such as riding a bike. Slow-wave, or non-REM (NREM) sleep, is associated with the consolidation of declarative (explicit) memories. These are facts that need to be consciously remembered, such as dates for a history class.

Increased learning

Popular sayings can reflect the notion that remolded memories produce new creative associations in the morning, and that performance often improves after a time-interval that includes sleep. Current studies demonstrate that a healthy sleep produces a significant learning-dependent performance boost. The idea is that sleep helps the brain to edit its memory, looking for important patterns and extracting overarching rules which could be described as 'the gist', and integrating this with existing memory. The 'synaptic scaling' hypothesis suggests that sleep plays an important role in regulating learning that has taken place while awake, enabling more efficient and effective storage in the brain, making better use of space and energy.