People have different circadian rhythms on average as they age. We simply associate the pattern of those middle aged and older with virtue. Middle age and old people raise children, and they teach children that the sleep patterns of the elders are wise and just, while the sleep patterns of the youth are slovenly and sinful. Our entire concept of "early" is defined by what middle age and older people simply adapt to naturally without force or effort. Older folks tend to wake up at a certain hour, so we just declare that the hour everyone is expected to wake at.

The most insidious form of this temporal bigotry is how we typically force high school students to start school at the earliest time of day of any school students, even though high school students have the latest natural waking time of any age group. We value "teaching lessons" to our youth more than we do actually teaching them. So we drag them out of bed at an unnaturally early hour so that they can make class at 7 AM. We then berate and shame them for being sleepy and inattentive in the unnaturally early classes we require them by law to attend.

And I say all this as someone in their late 30s who naturally wakes up pretty early. From an evolutionary perspective, it makes a great deal of sense why we have people with different natural sleep and wake times, and for those preferences to shift with age. We spent several hundred thousand years living as small groups huddled around campfires. Part of warding off predators is having people on watch through the night. Having people who don't have to fight to stay awake late into the night makes that guard duty so much easier. In prehistory, I imagine the young adults staying up late into the night after the adults are asleep, enjoying some time to themselves, tending the fire, and watching for predators. The last of the youth to go to sleep would trade off with the earliest rising of the elders. We are a social species. We are evolved to live in groups. And a group is more effective with a diversity across many characteristics, including sleep/wake times.

But we've forgotten this fact and turned a simple consequence of evolution into a moral issue. And for that, we as a society abuse our youth and force them to wake at unnaturally early hours for the sake of puffing up the sense of moral superiority of the middle aged and older. Collectively, our relation to early waking times, and especially how we use it to collectively abuse our children, is one of our greatest sins as a culture.