Wednesday, March 14, 2012

Nature's Way

A few weeks ago, I chanced upon this article from the BBC which suggests that for much of human history it was common for people to 'retire to bed' for most of the hours of darkness, but to wake up - and enjoy a reviving spell of activity - for a few hours in the middle. Apparently, this didn't really change until public streetlighting first started to become commonplace in Europe towards the end of the 1600s. Before that, the limitations of lighting technology meant that it wasn't safe or appealing to go out of doors at night, and even options for entertainment at home were fairly few. People used to dine at or shortly after dusk, and go to bed soon afterwards.

However, most people found it hard to sleep for more than 4 or 5 hours at a stretch, particularly when retiring so early; hence, it was supposedly a standard habit to rise for 2 or 3 hours in the middle of the night, and then return to bed to sleep through until dawn. In one of my earliest posts on here, I wondered how on earth Samuel Pepys had found the time for his prolific diarising; I assumed that he'd put in an hour or two before he went to bed each night, but perhaps in fact he was finding his writing hours between midnight and 2am.  References to 'first sleep' and 'second sleep' used to be commonplace, both in medical textbooks and in literature, and persisted through most of the 19th century (this brief anthology of such quotations, inspired by the BBC piece, begins with one from Dickens' Barnaby Rudge). Cervantes made gentle fun of Sancho Panza for his rare ability to make one sleep last the whole night long.

Nowadays, when most of us have longer days, harder nights, and turn in much later, one sleep is all we have time for; but we're usually exhausted enough to sleep for 6 or 7 hours at a stretch, and wake up reasonably well rested the next morning. Scientists speculate, however, that many sleep disorders - and particularly sudden wakefulness in the wee small hours - may trace their origins to this; they suggest that human diurnal rhythms favour the pattern of two shorter sleeping periods separated by an interval of activity, and that the eight-hours-a-night formula is an unexpectedly stressful imposition of modern life - 'unnatural' and potentially harmful.

Neither the BBC item nor anything else I've yet found on this discusses how or when eight-hours-a-night became the standard prescription. Nor is there any consideration of the custom of afternoon sleeping - siesta - in hot climates. Nor indeed of how cycles of perpetual night and perpetual daylight affect the sleeping habits of Lapps and Eskimos.

I did, however, discover a chap who is convinced that standing on one leg "to exhaustion" at least four times a day ensures a sound night's sleep, and a would-be scientific study that purports to confirm the benefits to creativity of REM sleep.

I have slept rather badly through most of the time I have lived in China, or, rather, in Beijing (I have slept very well in most other parts of the country I've visited). I attribute this to the fact that half of the city is a building site, and thus heavy plant is frequently rumbling up and down the street at odd hours of the night.


Harv said...

You need a "like" button, so that I can express appreciation for a post that I don't actually want to comment on.

BTW this post on sleep patterns much more interesting than the band names :)

Froog said...

How dare you, sir! The band-naming post is the most brilliant mass-participation forum on the Internet today, a pop culture phenomenon that is already the subject of at least three doctoral theses, and the best beloved of all my blog-children.

Perhaps there is a 'like' feature on Blogger I could activate, but I can't be bothered. I see there are options for you to share it via Facebook and Twitter - is that too much effort for you?

Even if you can't think of anything else to say, it's not really very much bother to open up a comment window and type 'like'. I don't know, young people today! You're all so LAZY - a single-click generation.

Ooh - band name!

Froog said...

I have to say, I'm a bit sceptical as to how 'natural' - or widespread - this 4-2-4 sleep-wake-sleep cycle was. I don't recall any references to it in Latin and Greek literature, for example.

I wonder if there have been any comparative studies done on the sleeping habits of primates?

JES said...

Here y'go.

Or here.

Or here (finally -- more than an abstract!).

Froog said...

Gosh, JES, the 'tireless trufflehound again'! Which of my several idle question did you find answers to? All of them??

Is there even a study of the sleeping habits of gorillas in Oslo Zoo, or of a pet chimpanzee in Nome, Alaska???

Froog said...

Hmm, that second one is particularly enlightening: "chimpanzee sleep behaviors are complicated interactions between both intrinsic and extrinsic factors". I.e., we didn't really find out anything.

John said...

Chinese school pupils take compulsory naps at some point in their packed schedules, I don't know if it's nation-wide or just in places with hotter climates though. The first time I heard of this I thought it must be quite embarrassing to be treated this way, after all it's akin to western nursery children taking a nap but maybe there's something in it and I guess they wouldn't know any different. Besides, Chinese people tend to mature a lot slower than in other countries I've found (again, perhaps not such a bad thing?) and I also don't know how much these naps carry on over once a student becomes an adult.

Froog said...

Hmm, not sure about this. Might be only at primary school - I haven't heard of older kids having to do this.

It might be a good idea if they did, though.

Lessons start at 8am, and they're sometimes expected to be at school by 7.30am - hence, often leaving home at 7am or earlier. And, once they get to middle school, they have such a ridiculous heap of homework that they're often kept up till midnight trying to finish it.

Hence, sleeping in class is considered perfectly 'normal' and teachers don't do anything to try to stop it.

The habit then persists through university and on into working life. It is widespread - and apparently pefectly 'acceptable' - for you to put your head down on your desk, resting on your folded arms, and just start zzzz-ing away any time you feel like it.

I always tried to make a stand against it when I taught in universities. "I don't mind you being too tired to come to class, but I do mind you sleeping in class. It is disrespectful to me, and distracting to your fellow students (especially when you snore so loudly!). If you're that tired, please go back to your dormitory and get some proper sleep."

Froog said...

Those primate studies JES found are pretty limited in their findings, but they do seem to suggest - as I'd suspected - that it's 'natural' to sleep as long as it's dark. The chimp study found that older animals tended to sleep a bit longer - and had "more efficient" sleep. Younger adults were lighter sleepers, easily disturbed; and adult males in particular tended to wake up and move around several times during the night - but that is speculated to be down to a need to watch out for predators (a drive that has withered away in humans). But there's no two-period sleep cycle; they might wake briefly from time to time to check for danger, but essentially they sleep all night long.

I have a hunch that this 'two sleep' habit (to the extent it existed at all; the evidence cited by the Beeb isn't all that profuse) was actually the 'aberrant', socially mediated behaviour, and that today's longer single sleep is more 'natural'.

JES said...

I haven't looked for something online about this just now, but... It seems to me there've been numerous recent studies about the value of taking a mid-afternoon nap -- either actually going unconscious briefly, or at least just closing the eyes and mind to the outside world for a little while.

Putting the two together, it would seem to make sense that if you cannot take the mid-day nap, which is true of (many? most?) adults, you'd need to sleep through the night.

Froog said...

Well, most people want to sleep through the night. It would seem to be an argument against daytime napping, if it makes you likelier to have a short or broken overnight sleep.

John said...

I regularly find I personally am quite refreshed after around 6 hours but finding it just a little too early will happily go back to sleep only wake a couple of hours later completely exhausted (thus backup up the arguments I've read here.) I once read on an Internet forum of some guy who had made a sleep plan, that he was quite happy with, where he only needed two hours of sleep a day. He would take 15-20 minute naps every few hours or so and that seemed to do fine for his extreme sleeping life-style. I think I'd find this a living hell myself but like that Bond villain, I'm sure he gets a lot done of a day.

Froog said...

I've always tended to rise very early in the morning (even though I rarely go to bed before 1am), but I tend to feel rather sleepy again in the early or mid afternoon.

It's a complex subject - and, basically, nobody yet understands very much about it at all.

Froog said...

Funnily enough, John, that story about the guy who supposedly gets by on multiple short sleeps each day is enormously popular in Chinese high school English texts. I have recorded accompanying listening materials about it dozens of times.

I've never got around to trying to dig up the original source. I suspect it's an apocryphal story.

I think the version I've come across suggests that he sleeps for 1 hour every 4 or 5 hours.

I suspect 15 minutes wouldn't do you any good, because you'd never get into the REM state. And trying to nap every 2 hours - or even every 4 hours - would be extremely limiting to normal activities. I suppose it might be feasible if you work from home (as I do!), but it would be next to impossible if you have to travel to business meetings a lot. And it would certainly kill the social life.

Harv said...

Ooh, I can share you on Facebook? What a good idea.

Chad said...

I'm a bit sceptical as to how 'natural' - or widespread - this 4-2-4 sleep-wake-sleep cycle was.

I think most people would agree that 4-2-4 is very advwenturous and only the bravest of sleep coaches would go for it. Even today, miost prefer a solid 4-4-2, though on occasion 4-3-3 can produce results.

Er. Hang on...

Froog said...

Yes, you can also 'like' me now, Harve. I trust that you will.

Steady on there, Chad! I knew someone was going to latch on to that possible connection (I nearly did myself!); but I think we should restrain ourselves until the European Championships in a couple of months.