BEST OF 2013 #1 - For decades brain scientists have struggled to find a scientific explanation for why animals need sleep. New research indicates it might be so that our brain can clean up the mess it makes while we are awake. Researchers have been able to demonstrate (using mice) that cerebral fluid is washed around the brain during active sleep patterns, flushing out waste products. This process appears to be more active during sleep because it takes too much energy to pump this fluid around during waking hours. Says one of the researchers: “It's like having a party. You can either entertain the guests or clean up the house, but you can’t really do both at the same time.” Except unlike with real parties, the house cleans itself while you sleep it off.