The article has a pretty good explanation of night owls vs. morning people, namely that the real reason people are one or the other is not the time of day they prefer, but that the night owl has a circadian rhythm that is longer than a 24 hour day, so they get out of sync and go to bed later and later until it bumps against the time they have to get up for work! Reading that is a personal vindication for me because I've said for years, and no one would believe me, that I run on a 28 hour rhythm. When I have no other commitments (like during the summer when I was still in high school) my sleep schedule would wrap around and around the clock. I believe I have an unusually long circadian rhythm compared to the norm, so going to bed at the same time just doesn't work for me; what actually happens is that throughout the week I get progressively less sleep until I crash and sleep all day, resetting the cycle.