"Scientists discover how a common mutation leads to ‘early bird’ sleep disorder
A new study by researchers at UC Santa Cruz shows how a genetic mutation throws off the timing of the biological clock, causing a common sleep syndrome called anticipated sleep phase disorder.
People with this condition are unable to stay awake until later in the evening (often falling asleep before 10 p.m.) and get up abnormally early in the morning..."
I'm sort of joking, but not quite. I can't think of an objective reason why being a 'night owl' is biologically an abnormality/deficiency. As many other commenters have pointed out, daily rhythms are socially/culturally imposed, not so much biologically determined.
There are many cultures (think of Mediterranean ones for example) where people routinely have late dinners and go to bed after midnight. Hard to imagine that entire countries are just biologically abnormal.