Staying on Summer time means additional sun after work for an extra month. Can go for a walk or do something outside in the sun.
And for those further South it doesn't matter anyway.
I'd like to see what the additional vitamin D from that extra sun does to sleep etc. I imagine that's not part of the study.
The age old morning people versus evening people. Sounds like the kids aren't morning people either.
We should probably start high school later in the morning even if we stay on standard time ; it's way more important if we switch to permanent daylight time.
It starts earlier so it can end earlier so that there is time for sports and other extra-curricular activities?
Teachers spend time with students doing these activities, and the teachers have lives too. If high school ends at (e.g.) 2:30 pm, there's 60-90 minutes that stuff can happen and teachers still have 'regular work hours' of 8-4 (a shifted 9-5) so they can do things in their lives.
Activities also can stop during the really dark weeks around the solstice in a way school can't.
Don't necessarily disagree, just laying out a (possible) reason for early start/early finish.
It also makes a world of different how earlier you get exposure to light in the morning:
It is so depressing to wake up, go to work in the dark and go home in the dark.