We go to school to learn, for example, science. Developments in science in the last 50 years have told us that with puberty comes hormonal changes. One such change is the timing and quantity of melatonin that the body makes. With puberty the amount is increased and it is released in the body later in the day, or make that later in the night. The effect of this hormone is that teenagers are more likely to naturally feel sleepy later than the rest of the community and then to need more sleep - 10 hours is recommended for them. But school starts at 8am to 9am in most places. What to do? I vote that society listens to the science it teaches, and starts school a bit later for teenagers. Happier teens and better school outcomes? That would be doing us all a favor.