Brain Never sleeps

Until the 1950s, most people thought of sleep as a passive, dormant part of our daily lives. We now know that our brains are very active during sleep. Moreover, sleep affects our daily functioning and our physical and mental health in many ways that we are just beginning to understand.

Read more: Understanding Sleep
Sleep: A Dynamic Activity
How Much Sleep Do We Need?
What Does Sleep Do For Us?
Dreaming and REM Sleep
Sleep and Circadian Rhythms
Sleep and Disease
Sleep Disorders
The Future
Tips for a Good Night's Sleep

http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm