Sleep too long?

I'm 17, and I feel the same way but in my case its when I go to bed at about between 1030 and 11 and wake up between 745 and 845 that I feel great. Any later or eariler either way and I feel like total crap. Ive read up on it on the internet, teens can get away with less sleep than adults and children, but most of the time teens like us will benifit with a lie in rather than going to bed eariler. I suggest you work out your best times like youve roughly discovered and keep to them during school days but try lie ins on the weekend as I find that makes me feel even better on monday morning.