about that pre-tech sleep study again: The one in which folks not living in typical modern life slept no more that most people in industrialized societies.
Question: If our lighted devices and electric lighting do disrupt falling asleep (which various bits of evidence suggests) then how in the world do we end up sleeping about the same amount? One possible answer: We also have technology that keeps the morning light at bay. It might also help that we’ve found ways to condition ourselves to wake at certain times that are far past daybreak.
Question: Pre-industrial Europeans were supposed to have had a first and second sleep, waking up in the middle of the night for a time. The folks in the study did not do so. What gives? Possible answer: The authors of the piece speculate that the Europeans, dealing with far longer nights during the Winter, developed a new sleep schedule as an adaptation. A second possible answer from me: One thing that leads people to wake in the middle of the night now is alcohol ingestion. Might these folks with “first and second sleep” have been drinking rather a lot compared to today’s standards? I’m not an expert in the history of alcohol consumption, but a brief look suggests it’s possible.
Question: The folks in the study didn’t report feeling tired despite getting what looks like little sleep. Yet many of us modern folk feel tired quite a bit on the same amount of sleep. Hypothesis: It’s because of what we’re doing all day. Having done some manual labor after not much sleep, I can say with some confidence that working with a computer all day on intellectual tasks makes me feel sleepier during the day (yet not more tired at night) than a day of shoveling soil. We could test this hypothesis by sending folks with complaints of sleepiness to do hard labor. I’m sure that would be a popular study.
Another unexamined aspect: the opportunity cost of sleep. It could be that both pre-modern and modern people have come to the same conclusion: sometimes there are things for which it’s worth staying up past your bedtime. They had flickering firelight, the Milky Way and keeping an ear out for tigers. We have Conan and Tumblr and loading the dishwasher.
Sleep is necessary but it doesn’t mean it’s always the best use of our time.