You may think you’re getting more accomplished by working longer hours. You’re probably wrong.There’s been a flurry of recent coverage praising Sheryl Sandberg, the chief operating officer of Facebook, for leaving the office every day at 5:30 p.m. to be with her kids. Apparently she’s been doing this for years, but only recently “came out of the closet,” as it were.What’s insane is that Sandberg felt the need to hide the fact, since there’s a century of research establishing the undeniable fact that working more than 40 hours per week actually decreases productivity.In the early 1900s, Ford Motor ran dozens of tests to discover the optimum work hours for worker productivity.