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Comment by mywacaday | Hacker News Reader

A single block of sleep is a relatively new behaviour, I suspect partially driven by the availability of cheap sources of light and heat. https://www.bbc.com/future/article/20220107-the-lost-medieva...

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This is a contentious theory with little actual historical backing. Most likely people have been sleeping in one block since forever.

> Most likely people have been sleeping in one block since forever.

Does that have stronger historical backing?

It is more common in high-latitude countries. Very uncommon in lower latitude.

Another unbacked claim.

There is a lack of historical writings clearly describing segmented sleep as a normal practice over monophasic sleep. If it had been the standard sleep pattern, one would expect abundant evidence for it.

Roger Ekirch’s theory, meanwhile, is based on what one could call a biased interpretation of a hand-picked selection of ambiguous sources.

I asked if there's abundant evidence for monophasic sleep in historical writings. Or do we just assume it was monophasic, because there's not much written about sleep either way?

You were asking for historical backing. Sleep is definitely abundantly mentioned in historical writing, while segmented sleep is not. I take the absence of the latter as historical backing.

Absence of evidence is not evidence of absence.

Monophasic sleep is mentioned, or just sleep is mentioned without hints on whether it was monophasic of polyphasic?

This is tantamount to saying that the Egyptians from the 18th Dynasty onwards did have horses but no black or white ones because while the historical records concerning warfare did mention horses a lot, nowhere is there a mention of black or white horses. I conclude the ancient Egyptians only had brown horses q.e.d.

I wonder how much time zones and seasons impact things. For example, in my city in the winter, it is often dark for 14 straight hours. No average, healthy individual would sleep for that long on a nightly basis. So, even if one slept for 7 hours at sunset, then there would still be 7 hours of darkness remaining upon awakening.

Point being, if one slept for 4-5 hours, wake up for a similar chunk, and slept the same amount again, then that'd be a great way to pass the time one could likely not use to do outdoor labor.

I would posit that the null hypothesis should be that uncoerced human sleep patterns and historical sleep patterns are similar to A: modern human sleep patterns, and B: the sleep patterns of a majority of diurnal mammals and especially those primates most closely related to us: namely "one big stretch of sleep while it is dark a majority of the time when not disturbed by external stimuli or illness".

If historical evidence does not do much to disambiguate this from the alternative hypothesis, then the null hypothesis would be the default presumption.

But the article discussed here also points in that direction when it mentions the importance of people on the lookout at night. The article also mentions primitive tribes partying all night, so that is yet another direction.

My boy when very young (just months) went thru a phase where in the middle of the night he would suddenly sit bolt upright, swivel his head to scan the room, and then conk out again. This was not caused by noises.

I found this reassuring and slightly amazing, that he is wired to do his part as a nighttime lookout.

Assuming you are not jesting, I am not certain I would qualify that behavior as any indication of being wired for some sort of nighttime patrol duty based on those details alone.

Not jesting! And, point taken. But it made me wonder. It was intentional (within the limits of intentionality for an infant) and repeated.

Fascinating. Also, not that you implied this by any means, but I was not trying to say "you are wrong, I'm right." Rather, who knows? Do all behaviors happen for a reason? Idk.

When I was in my early 20s, primitive tribes like Alpha Kappa Lambda would party all night.

That doesn't mean they didn't sleep all night, typically.

We have evidence that during the medieval period people did take two-sleeps. Whether this is the more "natural" organization is debatable. But it made sense for that time.

> Historical texts and recent research suggest an alternative view: that sleep can be naturally segmented into two periods across the 24h cycle – a pattern known as biphasic sleep

https://www.sciencedirect.com/science/article/pii/S138994572...

I believe that "little actual historical backing" could accurately describe what evidence that publication has provided, don't you?

Pages 341 to 414 of size 8 font denoting the manuscripts that he sourced from would disagree with you.

That theory is on rather shaky grounds: https://pmc.ncbi.nlm.nih.gov/articles/PMC10404514/

I would also imagine a single block of sleep is relatively new due a host of various factors. Especially when considering untreatable medical conditions, chronic pain, parasites (bed bugs, lice, etc.), lack of comfortable bedding, cohabitation with others, and plenty of other factors all had major impacts.

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