It's strange to me that adolescents are (or seem to be) wired to want to wake late and sleep late, since waking early and sleeping early is a predictor of a predictor of lower all cause mortality!
I read the abstract, pretty interesting. I did a word search for "wake" looking for if they talked at all about early waking times being correlated with overall regularity, as that has been my personal experience. Unfortunately they didn't talk about it, or if they did I couldn't find it.