[EpicEng]

But morning really is the default; it's our biological default. Most people wake up in the morning and go to bed at night naturally. Many people have small children, good luck remaining a night person with a 1 year old in the house. There are real reasons here, it's not just some arbitrary decision.

[saulrh]

Grades in primary and secondary school jump significantly if you push start times back from 8 AM to more like 10 AM. It may be the biological default to wake up in the morning, but there's absolutely nothing that says that peak performance should be reached the instant you wake up. If anything, I'd expect exactly the opposite! It takes time to get caches warmed, adjust biochemistry away from resting levels and toward operational levels, and get dumb maintenance tasks (breakfast, travel to workplace, "milk the cows") out of the way and move to higher-value and more complex activities (hunting, crafting, socialization). Until you do those things you're not going to be operating well, and many early-morning tasks wouldn't require peak performance and optimizations for an early peak would be wasted. I'd also expect intellectual pursuits to be more strongly affected; you need to be able to not get eaten by a tiger at absolutely any time, but you can choose when to sit down and start knapping flint or talking to people, which means you have more freedom and reward when optimizing the timing of peak performance on intellectual tasks.

[AnimalMuppet]

Biologically, don't most people wake up at dawn? That doesn't get you to the office at 7:30 AM in the winter.

That is, our schedule is not a biologically-based schedule. "Morning" (as defined by our society) is not the biological default.

[EpicEng]

Sure, but you're quibbling over an hour here or there. When people use the term "night person" they don't mean someone who wakes up at e.g. 8 instead of 7, we're talking about pushing back work by many hours, which just isn't possible for most people without a much shorter work day (I'm ok with that!)

[khedoros1]

Without electrical lighting and such, I'd agree. Sleep not long after sundown, a mid-night period of wakefulness, wake up for the day around sunrise. Ever since I can remember, my own default is to maintain activity late into the night, and then sleep as close to 8 or 9 hours as I'm permitted. Granted, that's a little rough if my 3 year old happens to wake up at 7:30, but 8:30 or 9 is pretty common for him; at 1, he often slept until 10, after being put to bed at 8pm.

8:30 - 10:00 seems to be the time range that I'll be ready to get up, when left to my own schedule. It's usually 2-3 hours after I wake up that I'm really ready to jump into a heavy project. The person who wakes up at 6 is right on target to start working, if they come in at 8. Me, I always feel like I could've used a couple more hours of sleep, even if I went to bed at 10pm the night before.