Sleep and learning
Encyclopedia
Many competing theories have been advanced to discover the possible connections between sleep and learning in humans. One theory is that sleep
Sleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...

 consolidates and optimizes the layout of memories, though recent evidence suggests this may be restricted to implicit procedural memories.

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. Many studies demonstrate that a healthy sleep produces a significant learning
Learning
Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...

-dependent performance boost. Healthy sleep must include the appropriate sequence and proportion of NREM
NREM
Non-rapid eye movement, or NREM is, collectively, sleep stages 1 – 3, previously known as stages 1 – 4. Rapid eye movement sleep is not included. There are distinct electroencephalographic and other characteristics seen in each stage. Unlike REM sleep, there is usually little or no eye movement...

 and REM phases, which play different roles in the memory consolidation-optimization process. In motor skill
Motor skill
A motor skill is a learned sequence of movements that combine to produce a smooth, efficient action in order to master a particular task. The development of motor skill occurs in the motor cortex, the region of the cerebral cortex that controls voluntary muscle groups.- Development of motor skills...

 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).

In a study, procedural memories have been shown to benefit from sleep (Walker et al., 2002, as cited in Walker, 2009). Subjects were tested using a tapping task, where they used their fingers to tap a specific sequence of numbers on a keyboard, and their performances were measured by accuracy and speed. This finger-tapping task was used to simulate learning a motor skill. The first group was tested, retested 12 hours later while awake, and finally tested another 12 hours later with sleep in between. The other group was tested, retested 12 hours later with sleep in between, and then retested 12 hours later while awake. The results showed that in both groups, there was only a slight improvement after a 12 hour wake session, but a significant increase in performance after each group slept. This study gives evidence that sleep is a significant factor in consolidating motor skill procedural memories.

Declarative memory
Declarative memory
Declarative memory is one of two types of long term human memory. It refers to memories which can be consciously recalled such as facts and knowledge. Its counterpart is known as non-declarative or Procedural memory, which refers to unconscious memories such as skills...

 has also been shown to benefit from sleep, but not in the same way as procedural memory. A study was conducted where the subjects learned word pairs, and the results showed that sleep not only prevents the decay of memory, but also actively fixates declarative memories (Ellenbogen et al., 2006, as cited in Walker, 2009). Two of the groups learned word pairs, then either slept or stayed awake, and were tested again. The other two groups did the same thing, except they also learned interference pairs right before being retested to try and disrupt the previously learned word pairs. The results showed that sleep was of some help in retaining the word pair associations, while against the interference pair, sleep helped significantly.

A study has also found that after sleep there is an increased insight
Insight
Insight is the understanding of a specific cause and effect in a specific context. Insight can be used with several related meanings:*a piece of information...

, that is, a sudden gain of explicit knowledge. Thus during sleep the representation of new memories are restructured.

A 2010 study has found that taking an afternoon nap increases learning capacity.

Electrophysiological evidence in rats

A 2009 study based on electrophysiological recordings of large ensembles of isolated cells in the prefrontal cortex of rats revealed that cell assemblies that formed upon learning were more preferentially active during subsequent sleep episodes. More specifically, those replay events were more prominent during slow wave sleep and were concomittant with hippocampal reactivation events. This study has shown that neuronal patterns in large brain networks are tagged during learning so that they are replayed, and supposedly consolidated, during subsequent sleep.

Sleep in relation to school

Sleep has been directly linked to the grades of students. One in four U.S. high school students admit 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
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 sleep deprivation is common with students because almost all schools begin early in the morning and many of these students either choose to stay awake late into the night or cannot do otherwise due to delayed sleep phase syndrome
Delayed sleep phase syndrome
Delayed sleep-phase syndrome , also known as delayed sleep-phase disorder or delayed sleep-phase type , is a circadian rhythm sleep disorder, a chronic disorder of the timing of sleep, peak period of alertness, the core body temperature rhythm, hormonal and other daily rhythms, compared to the...

. 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. As a result of studies showing the effects of sleep deprivation on grades, and the different sleep patterns for teenagers, a school in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, changed its start time to 10:30 a.m., in 2006, to allow students to keep to a schedule that allowed more sleep. In 2009, Monkseaton High School, in North Tyneside, had 800 pupils aged 13–19 starting lessons at 10 a.m. instead of the normal 9 a.m. and has reported that general absence has dropped by 8% and persistent absenteeism by 27%. Similarly, a high school in Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...

 has committed to providing at least one class per year for students who will start at 10 a.m. or later.

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
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...

 after the NREM phase, or that REM is needed to prevent stasis of fluids in the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

 (Roth Ari-Even et al., 2005).

See also

  • Dream
    Dream
    Dreams are successions of images, ideas, emotions, and sensations that occur involuntarily in the mind during certain stages of sleep. The content and purpose of dreams are not definitively understood, though they have been a topic of scientific speculation, philosophical intrigue and religious...

  • Preconscious
    Preconscious
    In Freudian psychoanalysis, the word preconscious is applied to thoughts which are unconscious at the particular moment in question, but which are not repressed and are therefore available for recall and easily capable of becoming conscious....

  • Unconscious mind
    Unconscious mind
    The unconscious mind is a term coined by the 18th century German romantic philosopher Friedrich Schelling and later introduced into English by the poet and essayist Samuel Taylor Coleridge...

  • Portal:Thinking
  • List of thought processes
  • Lucid dream
  • Sleep-learning
    Sleep-learning
    Sleep-learning attempts to convey information to a sleeping person, typically by playing a sound recording to them while they sleep....


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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