Everyone knows that teenagers love to sleep. And we’re not just talking about until 10 or 11 a.m., either — most teens we know could sleep until the early afternoon if they were able to. This is particularly perplexing to those of us who can no longer seem to get any shuteye past 8 a.m., even when we want to.
Well as it turns out, evolution could be the reason behind it all. Science has found that when humans sleep in groups, it’s pretty rare for everyone to sleep at the same time. In fact, there was a whole study dedicated to it.
Anthropologists, led by David Samson (formerly of the University of Toronto), studied the Hadza people in Tanzania to see what kind of role sleep played in people who lived in groups. These researchers monitored 33 adults from among 22 huts, attaching a Fitbit-like motion sensor to their wrists for 20 days. Of all those who participated, the researchers found that there were only 18 total minutes when everyone slept synchronously, which equalled about 0.01 per cent of total sleep time. The rest of the time at least one person was either awake or in a very light sleep, with roughly eight people awake at once during any given time.
So why the staggered sleep patterns?
As Mad-Eye Moody would say, constant vigilance. Depending on the age, certain people naturally seemed to be awake at a specific time in order to help protect the clan. That could be why teens sleep in later while grandparents go to bed earlier. It’s evolution, baby, and everyone in the group plays a part.
“While we tend to look at every deviation from the normal sleep pattern as a problem, it may just be part of human variation,” Samson said. “We are seeking to fill in a piece of the evolutionary puzzle.”
What’s super cool about this study is that it’s the first time sleep patterns have been studied outside of a lab under artificial conditions. That makes it one of the most important studies done in terms of sleep and our evolution as a species.
So the next time you get upset at the teen in your life for oversleeping, you might want to go easy on them. After all, they’re just doing what evolution [potentially] dictates, and watching out for the family.