The anthropology and ecology of sleep is surprisingly understudied, considering we humans spend roughly a third of our lives in such a vulnerable state. The best way to understand variation in modern sleeping behavior is to remember that sleep, like all human activities, is a culturally mediated event.

The stereotypical U.S. sleep experience, where one sleeps alone or with a partner, in a darkened, quiet room, on a raised cushiony surface with ample bedding, and one generally assumes they will achieve roughly eight hours of uninterrupted sleep is, anthropologically-speaking, really fricking strange. Our culture mediates how we sleep, and what we expect to experience. We expect quiet, even going so far as making nighttime noise violations punishable by law. We expect only a few culturally appropriate interruptions, mostly from minors in our care, or the needs of immediate family. We expect one block of uninterrupted sleep, almost exclusively during nighttime hours. We expect a pause of almost all cultural roles while we rest.

For most current humans, and the bits of sleeping history we can piece together from past humans, an individual's cultural roles extend into the nighttime realm, and sleep isn't as heavily divorced from the rest of human experience. In small scale groups members still have a job to do while most of us would be, well, just sleeping. In societies with more communal sleeping patterns (I'm most familiar with groups in the Amazon), someone is almost always awake over the course of the night. Someone is tending the fire, or singing softly, or comforting a crying baby, or walking out to go to the bathroom, or seeing why the dog is barking, or keeping watch. You sleep surrounded by the noise of other humans. For us that would be intolerable, but if you grow up in that culture the din isn't interpreted as sleep interruptions, but rather is as comforting reminder that one is surrounded and protected by extended family. Anthropologists discovered that even if sleep is interrupted during the night, cultural mores allow one to make up sleep through brief daytime naps, and the total time spent sleeping adds up to roughly eight hours. In these groups sleep is more fluid. Since they don't have our expectation that adults must only sleep in strict culturally appropriate times, they can catch up during the day.

Taking a deep anthropological view shows there isn't one best way to ensure the best possible sleep for all humans. Our sleep is as varied as our cultures. I couldn't sleep in an Ache pile, with mom and dad on either side and all their kids snuggled together between them. The Ache would (and do, we asked) think we're a little heartless to force kids to sleep alone in a dark, separate room away from everyone who gives them comfort. I personally found the siesta tradition a huge help in making up for interrupted sleep in the jungle, but others don't achieve the same refreshment through napping. There simply doesn't seem to be one single best answer to the human problem of sleep. It's fascinating.

Carol Worthman is the main anthropologist studying sleep, or was up until a few years ago. For a quick deep dive check out this Discover article for a brief introduction to the ecology of sleep.