Getting as little sleep as we do is 'un natural'. I'd argue that, including a nocturnal wandering break of some kind (as I recall hearing used to be normal prior to the widespread use of electricity) around 10 hours of darkness (on average) and 'rest at night' would be what we evolved as being setup for. To instead push the boundaries to midnight or later (as I tend to want to do my self) and then to be required to get up before even 8AM is really not leaving enough time for good rest.
It doesn't help that the area I'm in is closer to the 49th parallel than the 45th and also has easterly mountains; thus making natural sunrise artificially later. It's no wonder Seattle has such a caffeine addiction.
Before the advent of modern light, it was indeed common to have a brief period of being awake in the night.
It's also interesting to note that, during winter, it was not unheard of to basically hibernate, sleeping far more during the winter than the summer to preserve energy and food.
Unless it's icky and rainy outside, I generally find it difficult to stay asleep much past 7am. Even when I need it from staying up to 2am too many nights in a row.
I rather suspect it's staying up past sunset that's "unnatural", rather than waking around sunrise.
There is a wide variety of circadian rhythms, yours is just one of the most common, but it does not make it any more "natural" than the others. Some of us are night hunters, and no sunset can give us a sufficient kick.
Could also be that people who have a job are forced to wake up at a certain time in the morning whether they want to or not, whereas the unemployed have no such impetus to get out of bed early.
