Sleep and learning
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Many competing theories have been advanced to discover the possible connections between sleep and learning in humans. One theory is that sleep consolidates and optimizes the layout of memories, though recent evidence suggests this may be restricted to explict procedural memories [1].
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Sleep deprivation
Studies have shown that sleep deprivation leads to impaired consolidation of both declarative and procedural memories. As a result, humans do not improve on learned tasks and do not consolidate the learned material. In consecutive NREM and REM phases, memories are played back to and from the hippocampus so that their representations in the neocortex can be optimized. This, among others, serves generalization and minimization of memory interference.
According to some sleep clinic research, the negative effects of sleep deprivation are particularly dramatic in procedural learning.
However, new studies involving nootropic medications such as modafinil (Provigil™) show no decrease in memory skills following several days of sleep deprivation.
Increased learning
Popular sayings such as "sleep on it" or "consult the pillow" reflect the theory that remolded memories produce new creative associations in the morning. Many studies demonstrate that a healthy sleep produces a significant learning performance boost. Healthy sleep must include the appropriate sequence and proportion of NREM and REM phases, which play a different role in memory consolidation-optimization process.
A study [2] has also found that after sleep there is an increased insight, that is, a sudden gain of explicit knowledge. Thus during sleep the representation of new memories are restructured.
Other theories
Other researchers' theories on additional functions of sleep differ significantly. One older idea is the energy conservation theory. Others claim that REM sleep is needed to "refresh" the brain after NREM phase, or that REM is needed to prevent stasis of fluids in the eye. These theories have dwindling support in the sleep research community.
References
- Robertson, E.M., Pascual-Leone, A. and Press, D.Z. (2004). Awareness modifies the skill-learning benefits of sleep. Current Biology 14, 208-212.
- Wagner, U., Gais, S., Haider, H., Verleger, R. and Born, J. (2004). Sleep inspires insight. Nature 427, 352-355.
External links
- "To sleep, perchance to learn" (http://www.nature.com/nsu/010426/010426-15.html) - from Nature
- "Birds May Refine Their Songs While Sleeping" (http://www.sciencemag.org/cgi/content/full/282/5397/2163) - from Science
- "Study shows sleep helps improve memory" (http://europe.cnn.com/2000/HEALTH/11/22/sleep.memory.ap/) - from CNN
- Sleep Learning (http://www.sleeplearning.com) - "Learn While You Sleep - Languages, studies, self-help and personal growth"