So what is sleep for? More and more, it looks like memory and learning. And naps have the same effect!
the new research underscores a vast transformation in the way scientists have come to understand the sleeping brain. Once seen as a blank screen, a metaphor for death, it has emerged as an active, purposeful machine, a secretive intelligence that comes out at night to play — and to work — during periods of dreaming and during the netherworld chasms known as deep sleep
An Active, Purposeful Machine That Comes Out at Night to Play
Since then the study findings have come almost too fast to digest, and they suggest that the sleeping brain works on learned information the way a change sorter does on coins. It seems first to distill the day’s memories before separating them — vocabulary, historical facts and dimes here; cello scales, jump shots and quarters over there. It then bundles them into readable chunks, at different times of the night. In effect, the stages of sleep seem to be specialized to handle specific types of information, the studies suggest.
"We are such stuff
As dreams are made on; and our little life
Is rounded with a sleep."
William Shakespeare