Researchers discover REM sleep increases production of myelin precursor cells. What happens when we sleep? Here's a note I wrote in 2010 on how REM sleep changes the brain.


To sleep, perchance to oxygenate
UPDATE 2013:   Sleep increases the reproduction of the cells that go on to form the insulating material on nerve cell projections in the brain and spinal cord known as myelin, according to an animal study published in the September 4 issue of The Journal of Neuroscience. ...