This is interesting to me, because I am an individual who requires a lot of sleep. Since I was born, I've slept ridiculous amounts. 18 hours a day was not uncommon. Now that I am a teenager, which means that I am naturally a selfish, miserable hulk.
but back on topic, I have heard. From a number of different places/people that for every hour of sleep earned BEFORE midnight, the brain thinks it has actually received 2 hours of sleep. I walk to school in the winter. I live in Canada. I wake up at around 5 45-ish every school morning. If I don't go to bed by 10 30 or so, I will die in the first ciuple of periods. (School starts at 8. Calculate how long a walk that is, with 30 mins prep time.) IMO, if you find yourself tired, do a couple of things. First, simplify your mornings. Shower at night, pack lunch/backpack at night, whatever. Second, go to bed at least an hour before midnight. It will help. Also, to the adults who have posted, do remember that we are not adults. We are teenagers.
just my 0.02$.