Sleep scientists just calculated how much shut-eye you really need as you age—and it’s not 8 hours

One of the most important things for your health is something most people don’t get enough of—sleep. And while doctors have traditionally equated getting eight hours with a good night’s rest, new research suggests something different. A new sleep study, published in the journal Nature on May 13, finds for those in middle age and older, the “sweet spot” is somewhere between 6.4 and 7.8 hours. “Our study . . . shows that too little and too much sleep are associated wi...