The implied assumption in all this discussion is that everyone stays up late so 7am doesn't work. Perhaps the question should be why society is so geared for waking hours shifted partly into the night. Perhaps people should wake with the sun and sleep soon after dark. But so much entertainment is scheduled during the evening, and everyone is so deeply entrenched in their habits.
> The American Academy of Pediatrics, which backed the bill, said in 2014 policy statement that getting too little sleep puts teenagers’ physical and mental health at risk, as well as their academic performance. The organization cited research that shows that biological changes in puberty make it difficult for the average teenager to fall asleep before 11pm, and that teenagers need between 8.5 and 9.5 hours of sleep to function at their best.