THIS MAY VERY WELL BE A PHRASE TO SLEEP BY, as continued research and investigation indicate that the brain is processing memories and that learning occurs during sleep.

As science increases its understanding of the biological functions of different parts of the brain, a correlation develops between the brain’s information gathering and learning activity while awake and the same brain activity while asleep. These brain activities are monitored in the parts of the brain affiliated with memory and learning. Studies record nerve action, chemical changes, blood flow and other brain activities during learning and performances. When the same combination of brain activities occurs during sleep, it can be concluded that similar brain functions take place.

Sleep deprivation studies are another method for discovering the brain’s function during sleep. Different studies of task performance after a subject has been deprived of specific stage(s) of sleep are compared to the same task performance when those sleep stages have not been deprived. Various "rapid eye movement" (REM) and non REM sleep stages are explored. A time factor for performance within 3 days of the sleep deprivation is also used in these studies. The results have shown that sleep deprivation does affect task performance. Deprivations of certain sleep stages have resulted in different effects on performance. A comparison of these studies indicates which stages of sleep are related to the memories and learning affiliated with the task being performed.

Biological brain studies have primarily been done with animals as subjects. Sleep deprivation studies, on the other hand, use human subjects. The results of these studies are contributing to a growing body of evidence indicating that the following theories of brain function are occurring during sleep. 

During sleep stages, especially the rapid eye movement sleep stages, information obtained during the day is examined and meaning is derived. Learning that took place during the day is firmed up. 
             

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Memories not used on a daily basis are stored in dormant areas of the brain. During sleep, these areas are stimulated. Memories stored there are refreshed and kept ready for recall when needed. 
                     

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Memories are replayed and rehearsed during sleep. Learning occurs during this repetition. Demonstration of this learning is seen when these skills or visual perception are performed without any subsequent practice. 
       

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Sleep on it, use it or lose it.

See the EET articles "Sleep and Learning" and "Brain-Based Learning"

Carpenter, S. (2001). Research Confirms the virtues of 'sleeping on it', Monitor on Psychology, 32 (9). Retrieved December 7, 2003, from http://www.apa.org/monitor/oct01/sleeponit.html

Benkert, N. (February 1,2001). The Sleep and Memory Connection. ADVANCE Newsmagazine. Retrieved December 8,2003, from http://www.advanceforsleep.com/common/Editorial/Editorial.aspx?CC=4612

Gil-Verona, J. A., Pastor, J. F., De Paz F. J., Barbosa M., Macias, J. A., Picornell, I., Rami-Gonzalez L., Canizares, S., Boget, T. (2001). Neuropsychological Study Of The Sleep-Learning Relationship. Neurobiology of Sleep-Wakefulness Cycle,1 (2), 82-86. Retrieved November 30, 2003, from http://www.sleepcycle.org/v1n201/1/nssleeplern.html

National Institute of Mental Health, NIMH Press Office. (July 2, 2002). "Power Nap" Presents Burnout;Morning Sleep Perfects a Skill. Retrieved December 8, 3003, from http://www.nimh.nih.gov/events/sleep.cfm

Miller, R. (1998). Memory Consolidation and REM Sleep. Retrieved November 30, 2003, from Serendip, a Bryn Mawr College web site: http://serendip.brynmawr.edu/bb/neuro/neuro98/202s98/paper2/Miller2.html