there is no time period which teenagers are more able to fall asleep
This is unequivocally false. That’s literally a part of the circadian cycle. We can more easily fall asleep at particular spans of our 24 hour cycle. These spans shift depending on our age.
The point is that we now know this to be true. Rather than try to shoehorn our biological needs in whatever spare pockets of time we can scrounge, we should focus on better adapting our society and it’s systems to our needs at all stages of life.