Wow, this is so interesting! Sleep rhythms are different for different age groups, and this may have originated as a means to keep families safe from predators. Because if family groups sleep huddled up together, there’s always somebody awake, or sleeping lightly.
I should write about this! Well I am writing about this, but write-write, for an actual website, with readers and stuff.
I do write for ‘real websites’ actually, but many ideas get lost due to lack of time or focus. Which brings me to my next thought: ADHD often goes with a slow(/late) circadian rhythm. Maybe this is an adaptation too? We’re supposed to be night owls, saving our friends and family from stalking cave lions while everybody else is asleep? Except for teenagers of course. Who needs people with ADHD when you’ve got teenagers?