During puberty, youth undergo a shift in their circadian clocks that makes it harder for them to fall asleep until later in the night. Meanwhile, they can stay awake longer before experiencing an increase in the pressure to sleep

https://www.apa.org/topics/children/school-start-times

https://www.washington.edu/news/2018/12/12/high-school-start-times-study/

https://www.theguardian.com/science/2025/apr/22/teenagers-bed-early-sleep-longer-sharper-brains-study