I am no psychologist but it’s about how their day night cycle develops which is very different from adults.

Daylight is one of the systems it uses to self regulate and start feeling awake.

School actually starts to soon in many places, that already a major part of it. Research (not at hand) actually show grades go up if school starts later. We basically force kids to be tired to fit our schedule and it gets worse for teens.

With delayd sunlight. They wont really be properly awake for almost half their “productive” day”.

We also know that lack of sleep is a pillar of mental health conditions, now include all the dormant mental health conditions kids already carry and with growing up in this timeline.