This question came to me when I came across a study claiming that people who live in the upper floors of apartment buildings feel more secure at night. Duh, right? A territory that’s hard to invade is a plum territory whatever species you may be. But then I got to wondering if this is why we also tend to sleep upstairs.
Duh again? Probably.
The history of bedrooms is pretty brief: Until quite recently, we slept on the ground, on crumpled up plants or animal skins. To say we were vulnerable in our slumbering state is an understatement. The invention of walls allowed us to harden the defenses during this perilous overnight period. But windows were only adopted about five minutes ago, historically speaking: In the long, dark era between the invention of the wall and the invention of the window, to accomplish much of anything besides sleeping, we had to go outside where we could see.
A number of cultures have paused house development right there. The Korowai people of Papua, New Guinea, build their one-room houses in treetops, where extended-family members hang out with pigs and whatever else is valuable enough to haul up the ladder. During the day they descend to tend gardens, hunt, gather, and let the pigs stretch their legs. But their down-time is spent in the safety of the tree-fort. The igloo and the tee-pee are similar: They’re not good for much beyond sleeping.
But with the rise of “civilization” and economic disparity, a class of folk emerged who didn’t have much need to go outdoors. These people delegated their food-chasing and enemy-spearing to others. In the great halls of medieval Europe, great walls protected a heated space where the upper class could plot, play, and sleep en masse.
Further income disparity produced greater domestic stratification, as the cream of the crop now built a fort-within-a-fort over the great hall. Like the great hall this was a multipurpose space, where business, pleasure, and sleep took their turns.
So this seems to be the nub: Sleeping was a fairly public, or at least social, activity for most of human history. And as humans gain wealth, we often seem to spend it increasing the privacy and security for our sleeping hours.
And like many other creatures, we seem to understand intuitively that the higher you climb, the safer you are.