Brain areas disconnect during deep sleep - LiveScience - MSNBC.com

"Your brain never stops working. But it does cease talking to itself when you lose consciousness, a new study shows.

Scientists have long wondered what the brain does and doesn't do during deep sleep. It remains active, they know. So what's the difference between consciousness and the lack of it?

When we're awake, different parts of the brain use chemicals and nerve cells to communicate constantly across the entire network, similar to the perpetual flow of data between all the different computers, routers and servers that make up the Internet.

In the deepest part of sleep, however, the various nodes of your cranial Internet all lose their connections.

"The brain breaks down into little islands that can't talk to one another," said study leader Giulio Tononi of the University of Wisconsin-Madison."