From lower test scores to depression and even traffic deaths, the evidence is piling up that early school start times are bad for teenagers. So why do schools in the US start so early?

Teens have different physiological needs when it comes to sleep, due to their changing bodies and the energy needs that go along with it. Because of this, multiple health agencies including the Centers for Disease Control, The National Sleep Foundation, The American Academy of Sleep Medicine, American Academy of Pediatrics, and the American Medical Association have pushed for later start times – 8:30am or later.

But for various reasons (usually money) only 1 in 5 schools actually start at the recommended time.