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Have you ever heard of polyphasic sleep? Or biphasic sleep? Poly, as a prefix, means many. And bi-, as you know, means two. Phasic simply refers to phases. So, polyphasic sleep means sleeping in several phases, while biphasic sleep means sleeping in two phases. Either is just a fancy way of saying sleeping more than once, the way most animals besides we humans do. People make a lot of cats taking cat-naps throughout the day. But really, your dog sleeps this way and other great apes do this as well. Why are we humans different?
Well, as Andrew Perlot reveals in this video, we are not fundamentally different. We have artificially lumped out sleep period into one long slumber in order to function in an industrial world. In other words, our sleep is monophasic. We introduce artificial light to extend a quasi-daylight period for at least 16 hours a day. And if you live in a city, like me, you need blackout shades to ever completely get rid of this light. The streetlights outside my house are WAY bright. It is the light cycle that affects our natural sleep pattern, which is called out diurnal cycle.
Andrew does a brilliant job of thoroughly explaining about biphasic sleep and his experiment to try it out for a while. This does appear to be a quite natural way of sleeping that a human will simply slip into without trying if the artificial light cycle is curtailed so that there is no light after the sun goes down.
So Natural Biphasic Sleep Is Better, Right?
I think a lot of folks, upon hearing or reading that this is “naturally” a pattern of sleeping a human will adopt in the absence of an extended light period, will assume, “oh my, this is why we are so sick. The way we are sleeping is killing us! We must do things like our ancestors!”
Well, as Andrew said, he has seen evidence of this practice by the Romans, referring to “second sleep”, for example. This was when a person would basically go to sleep when the sun went down and wake up sometime in the wee morning hours, be awake for two or three hours, and go back to sleep. But, well, see, we live much longer than Romans did, on average. We are not dying. We are living longer and longer lives. So, just as Andrew said, this is interesting, but let’s not get ahead of ourselves.
The video is entitled “What Two Weeks Of Biphasic Sleep Did To Me.” So, what did it do for Andrew, physically? Nothing, really. He did not feel more rested, and he was not more productive. I’ll get into the productive part of it later below, including the practical considerations. But, Andrew said, at the end, “…it was roughly the same amount of sleep just not broken up.” The point is there was nothing magical about breaking up the sleep period that caused him to feel more rested, or really, different in any way physically. He did feel different in other ways, but watch the video to find out what that means.
Did Pre-Historic Humans Sleep Differently?
We can pretty much deduce the sleeping and waking behavior of prehistoric humans by observing other primates like apes and monkeys. Most nonhuman primates sleep polyphasically, with frequent sleep periods throughout the day and up to 12 periods of waking activity. However, the chimpanzee actually has a long sleep period from dusk to dawn of about 10 hours, and then a nap of about five hours during the day. But during the night-time sleeping, they awake frequently for brief periods of time, and during the mid-day nap.
It is likely the prehistoric man slept something like this, with a major 10 hour (give or take) sleep period during the dark hours, with frequent brief awakenings. Whether there was a long nap, like a siesta, during the day, is difficult to know. One thing to realize, and this goes back to what I was saying about our health, is that prehistoric people had a lot more to disturb their sleep. For one, they had to be concerned with predators, and two, they probably had a lot of ailments that caused sleep disturbance, such as parasites, arthritis, and even tuberculosis. What happens to your sleep when you are in pain or you are uncomfortable? Well, prehistoric people did not have the resources you do to affect that comfort level. If you wake up with a headache, you can take a pill and fall back asleep. 1Pollak, Charles, et al. The Encyclopedia of Sleep and Sleep Disorders. Facts on File, 2010.
In Andrew’s experiment, and in the study he talked about, people exposed to a strict light cycle without prolonged artificial light would wake up once and move around for a couple of hours. Something occurs to me. How much do our expectations and rationalizations of how we should sleep affect how we react to waking up for a period? Would a prehistoric person think, well, I’m awake, I may as well get something done? Or would they open their eyes for a brief period, roll over, and go back to sleep? In other words, sleep is loaded and we should not assume that any pattern we fall into is absolutely primordial.
What we can say almost certainly is that our monophasic sleep pattern is a societal artifact and does not come from any innate physiological process. The next time you wake up during the night and think, oh, no, I can’t sleep, consider that there is nothing weird about waking up during a long period of sleep. The problem is that you know that if you do not get back to sleep, you will be tired the next day and you will not have an opportunity to go chimpanzee and nap for five hours.
However, even animals that are considered polyphasic are still strongly influenced by circadian rhythms and will sleep more or less during the light period or the dark period. You may have heard of many animals being nocturnal. This only means that they get most of their sleep during the daylight hours, not that they never ever sleep at night.
Napping Is Normal
There is a lot being made of the effect of not getting your eight hours (or seven hours) of sleep every night. There is nothing wrong with taking a nap during the day because you feel the need for a little more sleep. It doesn’t mean you are lazy and it is absolutely and utterly a natural thing to do.
But, we don’t want to go assuming, as some people already have, that a fragmented sleeping pattern existing primarily of “microsleeps” is the way you are supposed to sleep. What matters the most is how voluntary or involuntary these sleeping patterns are. If you are overwhelmed by the need to take a nap every day, fall into a deep slumber, and force yourself up only to feel horrible for hours, or never fully awake, then you either need more sleep or you are having some type of sleep disturbance. Voluntary naps can be a very healthy thing to do, though. 2Stampi, Claudio. Why We Nap: Evolution, Chronobiology, and Functions of Polyphasic and Ultrashort Sleep. Birkhauser, 2014.
Is Biphasic or Polyphasic Sleep Practical?
When Andrew got up during the night, he entered into what he described as a peaceful and almost meditative state. He didn’t turn on his laptop and start working. He didn’t, as far as I can tell, do anything other than enjoy the peaceful early morning hours. If you think that trying out this biphasic sleeping pattern means you’ll get more done, think again. Unless that is, you can get things done in darkness. As soon as you turn on a light and try to take care of those dirty dishes you left the evening before, you’re gonna slap yourself right out of this pattern. It is governed by the light and dark sequences. The waking period is just being awake, not being awake and functional. And, chances are, if you start moving around too much in general, you will end up not falling asleep again.
And, in order to do it, you’d have to separate yourself from normal human society. You would, in effect, be isolating yourself from other humans. We are social animals. We don’t all follow the same sleeping pattern just because of artificial light, but because, well, we all follow the same patterns!
Blue Light Pollution?
My tablet has a “blue shade” function. What it does is filter out the blue light from the screen, making everything a sort of red-brown color. The idea is that the blue light from our devices, used at night when we are supposed to be preparing for sleep, interferes with our daily circadian cycle, keeping us awake.
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The retinal ganglion cells in your eyes respond to light and darkness and communicate with your brain set your daily sleep cycle. Does all this light interfere? You bet it does. Certain photosensitive ganglion cells contain melanopsin. These cells are particularly sensitive to short-wave blue visible light, transmitting this information directly to a part of the brain called the suprachiasmatic nucleus (SCN) located in the hypothalamus, otherwise known as your body clock. To put it simply, your eyes associate blue light with daylight. When this signal reaches the brain, it shuts down the production of melatonin. without enough melatonin, you may find it harder to fall asleep and have your sleep disturbed.
If you absolutely must be on your laptop late at night, you can actually download a software called Flux, which will adapt your computer’s display to the time of day. At night, it will remove a lot of blue light.
A pair of blue-blocking glasses, however, may be an even better solution. 3Rosenberg, Robert S. Sleep Soundly Every Night, Feel Fantastic Every Day: a Doctor’s Guide to Solving Your Sleep Problems. DemosHealth, 2014. And, if you have a lot of light pollution streaming through your windows at night, you can try blackout shades or curtains but an easier and much less expensive solution is a simple sleep mask like the popular Alaska Bear Natural Silk Sleep Mask. I personally use this mask to deal with the extra-bright street lamps that keep me up at night. These things are so annoying they even keep the birds up!