On October 15th, 2015 we learned about

Rethinking which society has the superior sleep schedule

Supposedly, we all used to sleep better. Before our work schedules split from natural circadian rhythms, before electric lights artificially shortened our nights, and before various devices kept us transfixed long after we meant to “take a quick look” at our preferred social media site. Personally, I remember sleeping better before my kids were born, but even then I certainly wasn’t going to bed at sundown and starting my day refreshed at sunrise. Which may, it turns out, be completely normal.

Defining our inherent sleep schedule

It’s hard to know how humans used to sleep, since we’re still working on tracking how humans sleep today. Documents from Europe in the last few hundred years indicate that people used to go to bed earlier, wake for a bit at night, then sleep until dawn. Even if these notes were representative of the average human at the time, that’s not really long enough ago to necessarily be the last record of humans sleeping according to our evolutionarily-determined needs. For a different reference point, researchers have now tracked the sleep habits of three “traditional” lifestyles from Tanzania, Nambia and Bolivia to see how they rested up each night. They might not be the ultimate proxy for an undisrupted human schedule, but without any contact with each other, similarities would probably have stemmed from a basic need rather than current fashion.

Their day wasn’t quite the fabled experience described above. They generally went to bed two to three hours after sundown, which may have been influenced not by light but by the ambient temperature. They’d then sleep for around seven to eight and a half hours, waking up before sunrise to start their day. Again, the timing in the morning seemed to be tied to temperature— rather than pull the quilt back up for more snoozing, these people got out of bed. There was occasional napping, more often in warmer weather, but nothing that seemed to be core to their circadian rhythms.

Benefits of consistency

This isn’t to say that their sleep health was no better than the average westerner staying up past midnight to write a blog though. Insomnia was such a foreign concept to all three cultures that none of them even had a term to describe the idea. Researchers theorized that the keys to their consistent sleep were when they were exposed to sunlight, the responsiveness to temperature and just being consistent overall. Sunlight exposure seemed to be most concentrated when working outdoors in the morning hours around 9 am. By noon, all three cultures were likely to seek shade, but that earlier activity helped set their internal clocks.  Then by waking up at the same time each day, they were able to keep their body on regular and effective schedule.

So for anyone struggling to sleep, consistent light exposure and scheduling may be the easiest features of primitive human sleep to adopt. Which is good news, because if we all needed to shift to a schedule where we were up for an hour in the middle of the night, it’d be mighty hard to keep a lid on accidentally watching cat videos until dawn, ruining the whole concept.

Source: What You Can Learn From Hunter-Gatherers' Sleeping Patterns by Ed Yong, The Atlantic

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