They literally are. And that time is later than adults. That's what circadean rhythms are.
As someone who was recently a teenager, if school started an hour later, I would have stayed up another hour. Most of my friends were the same way.
One of the things people seem to miss is late nights are generally when teenagers have the most freedom. With your parents asleep no one is awake to bother you.
IMO, general level of education is important to fostering future curiosities.
Additionally, what about the teens who do get up early? I feel like these studies are sometimes trying to explain something that really is simple to understand. Kids stay up later today because there is so much more keeping them awake. If they stay up late, then they need to sleep later to get the sleep they need.
Growing up, my friends and a I almost all got up with the sun. All the activities we wanted to do revolved around the daytime. As a consequence we were usually asleep not much later than 10pm.
School schedules currently require many teenagers to get up before the sun just to get to classes, let alone before-school activities.
The proposal is to start classes no earlier than 8:30. According to the statistics in the article, 14% of schools already do. 90% would have to change their start times by an hour or less. That's also around the time most adults arrive at work.
The few early risers can find something to do with the extra time, be happy for their friends, and take comfort in the lower rate of car accidents.
I think it would make much more sense to change the content of school during those years to reflect the interests of students better. Let them take a break, do something practical, do projects, etc. instead of trying to cram facts into their heads. A lot of stuff I headed to learn when I was 13 I learned easily 5 years later, and vice versa.