Teens are right: getting up later is good (for grades)

In 10 seconds? Letting adolescents sleep in and pushing back school start times is good for their academic results, makes them miss classes less, and reduces health risks, scientists have found.

What exactly did they discover? They've found that teenagers' grades and punctuality improved by around 5% if they were allowed to get 40 minutes of extra sleep on school days. In addition, their wake times on weekdays and weekends would be more in synch. In other words, their 'social jetlag' would reduce, allowing them to better align their sleep times to their circadian rhythms.