I love sleeping. It is both necessary and restorative, but I had no idea what critical mental housekeeping functions occur while you snooze. While it is true that we sleep on average a third of our lives, without it, our life expectancy would undoubtedly be shortened. Our brains go through cycles of specific activity from short bursts of high output, or spindles as neuro-scientists call them, where memories are strengthened through repetition, to slow-wave, high amplitude dee