Sleeping 8 hours means nothing if you're doing it at different times every night — a 60,000-person study just proved consistency beats duration when it comes to staying alive. People with the most irregular sleep schedules had a 53 percent higher risk of dying from any cause, even after researchers controlled for how much sleep they were actually getting. The metric we have been told to obsess over for decades, total hours, turned out to be the weaker signal.