What makes sleep so mentally refreshing? University of Rochester neuroscientist Jeff Iliff addressed the crowd gathered at a September 2014 TEDMED event and explained his amazing new discoveries.¹ The words he used perfectly match what one would expect while describing the works of an ingenious designer.²

Scientists purposefully made mice sick to test how the creatures’ intestines—and the microbes they harbor—would react. They discovered details behind a remarkable relationship that, when working well, keeps both parties healthy.