Sleep on It: Sleep might just be the most important part of daily health—and the biggest new target for biomedical engineering.

Every night, around the world, 7 billion people lie down to sleep. Their eyes close, their bodies relax, and their brain waves begin to smooth from the chaos of wakefulness into slower, synchronized waves. As their thoughts begin to lose coherence, a part of the brain called the ventrolateral preoptic nucleus, located deep behind the eyes, begins to blanket the nervous system in quieting chemicals like gamma-aminobutyric acid and galanin, shutting down the networks of wakefulness and turning off the body?s awareness of the world around it. It is the most important part of these people?s days.