This is a really interesting and thought provoking interview.
http://www.cbc.ca/video/news/audioplayer.html?clipid=2421296702
In the first 10 - 30 minutes of sleep a mouse brain increases the exchange rate of cerebrospinal fluid (CSF) into and out of the brain having a complete exchange of fluid in the brain. This is a 10 - 100 fold increase in circulation compared to an awake mouse. This seems to "sweep" out the brain of metabolic wastes. This could be helpful in the prevention of Alzheimer's disease.
Just another good reason to be getting a good nights sleep!
