Sleep and learning

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 explicit procedural memories.

Increased learning
Popular sayings such as "sleep on it" or "consult the pillow" reflect the notion that remolded memories produce new creative associations in the morning, and that often performance improves after a time-interval that included sleep. Many studies demonstrate that a healthy sleep produces a significant learning dependent 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. In motor skill learning, an interval of sleep may be critical for the expression of performance gains; without sleep these gains will be delayed (Korman et al, 2003). However, several studies show that, in some conditions, time after training, even without sleep, may suffice for attaining significant performance boosts (Roth Ari-Even et al, 2005).

A study 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.

Sleep in relation to school
Sleep has been directly linked to the grades of students. One in four U.S. high school students admits to falling asleep in class at least once a week. . Consequently, results have shown that those who sleep less do poorly. In the United States sleep deprivation is common with students because almost all schools begin early in the morning and many of these students choose to stay up awake late into the night. As a result, students that should be getting between 8.5 and 9.25 hours of sleep, are getting only 7 hours. Perhaps because of this sleep-deprivation, their grades lower and their concentration is impaired.

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.