http://www.theatlantic.com/magazine/archive/2013/10/the-case...
"During football season in particular, the focus of American principals, teachers, and students shifts inexorably away from academics. Sure, high-school football players spend long, exhausting hours practicing (and according to one study, about 15 percent experience a brain injury each season), but the commitment extends to the rest of the community, from late-night band practices to elaborate pep rallies to meetings with parents. Athletics even dictate the time that school starts each day: despite research showing that later start times improve student performance, many high schools begin before 8 a.m., partly to reserve afternoon daylight hours for sports practice."