Submitted by ebb5 t3_y7s95g in askscience
CyborgCabbage t1_isy1ifi wrote
Reply to comment by undergroundsilver in Is our sleep pattern based off the length of the day? by ebb5
Bimodal sleep may be limited to Europe:
>Historical evidence suggests that “until the close of the early modern era, Western Europeans experienced two major intervals of sleep bridged by up to an hour or more of quiet wakefulness” [33 ] (see also [30 ]). Our results suggest that the bimodal sleep pattern that may have existed in Western Europe is not present in traditional equatorial groups today and, by extension, was probably not present before humans migrated into Western Europe. Rather, this pattern may have been a consequence of longer winter nights in higher latitudes. In this view, the “recent” disappearance of bimodal sleep was not a pathological development caused by restricted sleep duration, but rather a return to a pattern still seen today in the groups we studied, enabled by the electric lights and temperature control that restored aspects of natural conditions in the tropical latitudes.
nick_shannon t1_isy7gle wrote
Most weekends I sleep from around 5pm to 10pm then I’m up for a few hours and I go back to bed about 1am and then get up around 5-6am
[deleted] t1_isyrnth wrote
[removed]
Quakarot t1_iszfw5l wrote
The bbc article suggests otherwise:
> Biphasic sleep was not unique to England, either – it was widely practised throughout the preindustrial world. In France, the initial sleep was the "premier somme"; in Italy, it was "primo sonno". In fact, Eckirch found evidence of the habit in locations as distant as Africa, South and Southeast Asia, Australia, South America and the Middle East.
So it’s unclear, at least, but the bbc article also suggests compelling evidence that biphasic sleep exists even today in Africa, and other places without artificial light
> Back in 2015, together with collaborators from a number of other universities, Samson recruited local volunteers from the remote community of Manadena in northeastern Madagascar for a study. The location is a large village that backs on to a national park – and there is no infrastructure for electricity, so nights are almost as dark as they would have been for millennia.
> The participants, who were mostly farmers, were asked to wear an "actimeter" – a sophisticated activity-sensing device that can be used to track sleep cycles – for 10 days, to track their sleep patterns.
> "What we found was that [in those without artificial light], there was a period of activity right after midnight until about 01:00-01:30 in the morning," says Samson, "and then it would drop back to sleep and to inactivity until they woke up at 06:00, usually coinciding with the rising of the Sun."
> As it turns out, biphasic sleep never vanished entirely – it lives on in pockets of the world today.
TuhmaMyy t1_isyoik4 wrote
This is really interesting! Thank you for the link.
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