The Night Janitors of the Brain: Do you think other species ever look at humans and raise an eyebrow at the amount of sleep we need? Do cockroaches and eyelash mites leave messages on our foreheads in microscopic Sharpies? Perhaps "I just popped on an apex predator's head." We may be the most successful species in existence, but that doesn't mean sleep is just another one of our "choices" as a human being. It is a necessity for survival, even though it requires immobility and vulnerability. Prepare to meet the night janitors of the human brain.