Most teenagers aren't staying awake til 3am, it turns out. And you can test your theory in several ways - either by checking American teenager sleep habits against those in other countries where school does start later (e.g Australia - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941425/figure/...), or by looking for the existing studies that have been done on changing school times (e.g this one in Norway https://teensneedsleep.files.wordpress.com/2011/05/school-st...)

Summary: your theory doesn't appear to be supported by data.

Most adults need 6-8 hours of sleep. Kids need more than that.

https://www.nhs.uk/Livewell/Childrenssleep/Pages/howmuchslee...

For some reason the sleep pattern changes for adolescents. Now that I'm in my 30s, waking up early is no big deal, but waking up before 8 was a huge struggle and I was always an advocate of 8 hours of sleep for myself.

Here's a summary of the issue: https://sleepfoundation.org/sleep-news/school-start-time-and...

There may be something to it. At least, when I was young, I could accumulate a lot more sleep-debt before there were consequences.

These days (I am 37 now), when I go to bed an hour later than usual, I will feel it all day. Might not be a huge deal, but I notice it.