I'm pre-T so I can't comment too much, but teenage boys are pretty much renown for being lazy and sleeping too much, so it could just be the same thing effecting you as you're pretty much in the state of a pubescent boy.
My girlfriend's just forced me to sort my sleeping pattern out, it's been terrible for years, going to sleep about 4am in the morning and getting out of bed at 4-5pm, except the days when I have to be up at 6am to get to college and I just end up sleeping through lectures. It feels brilliant now, so it might be worth trying other times of sleeping out.