Is getting early really good?

I searched quite a few webpages, some says that it is beneficial (as the one I cite), some say that it is bad, especially if a person is genetically a night owl, and I suspect that websites as Fortune, Virgin, Forbes, etc. have an interest to say people that they should wake up earlier and work harder. Anyway, Harvard medical school and some researches also recommends getting up earlier (and going to bed earlier). But it seems that there is not so much scientific references about it. What are your thoughts?