There is a tribe in the Amazon called the Pirahã that still live in relative isolation today. There are at least 200 of them out there in the rainforest. The Pirahã have been invaded by the modern world in recent times, but when their isolation was first broken, it was a different matter. The Pirahã seemed to be culturally very different from their neighbors, and in fact, in many ways they were idiosyncratic among the cultures of the world that we have studied.
They kept no history for they did not value history. They worshiped no gods and had no religion. Their language has only ~10 sounds (the fewest in a language known to us) and can be spoken over long distances entirely through whistles. They had no counting. They had no words that describe colors. They seemed not to understand the act of drawing on a conceptual level and at first proved incapable of replicating simple drawings made with sticks in the dirt; however, they did on occasion create striking models out of sticks and bark twine to communicate sights they had seen. But these they destroyed the moment they were done, much as teachers erase chalkboards behind them while giving lessons.
And they were adamant they not learn any of these things anytime soon, because they did not recognize the value of learning new things; possibly the most important "value" recognizable (at least recognizable from our cultural perspective) they have is a resistance to coercion in all its myriad forms.
They are Pirahã. And Pirahã do Pirahã things and Pirahã things exclusively. If they must ford a river that has swollen they will brave it on simple ad hoc rafts. On the insistence of a researcher whose presence they are tolerating, they will watch with gripped bemusement as an expert craftsman from a nearby tribe builds a wooden canoe that could get them across with little danger. But they will not then attempt it themselves though they no doubt could, adept at visual learning as they are. Building a canoe is not a Pirahã thing.
To the Pirahã such unnatural foreign behaviors or languages are called "crooked head". Most things fall in this category. What must you do to straighten your head a little then? Well, the Pirahã are clear that only Pirahã can be Pirahã. But should you want to try, you could start by going hungry for days. This they do deliberately, outside of necessity, to strengthen their own characters and to engender resilience.
They seldom sleep for the same reason. And I do not mean that they do not sleep through the night as the vast majority of all people do. Nor that they break sleep into a few discrete chunks like a few others. They sleep in ~15 minute periods as rarely as biology will allow (like Salvador Dali was said to until it drove him nuts).
The Pirahã's lives are very hard in the jungles of the Amazon, especially isolated as they are from the accumulated technology and knowledge of all the rest of humanity. To concern ourselves only with living dangers they face: tribal enemies, jaguars, venomous spiders and bugs, mosquitoes carrying malaria and other diseases, and perhaps most deadly (and most ingrained in their cultural consciousness), snakes. Some who have studied the Pirahã see their voluntary insomnia as a behavioral adaptation to survive these intense around-the-clock challenges to survival.
Certainly the Pirahã see it that way. When the Pirahã leave one another at the end of the day, they do not say farewell with "goodnight" or "buenas noches" or "sayonara" or anything like anything you have ever heard. They say:
Don't sleep. There are snakes.
As in, "Do not sleep. Snakes exist." That may seem strange--it is certainly far outside of my own experiences. But move past the incongruity of it with me for a minute.... aren't there snakes?!
Well, for us there are and there aren't. Here we don't really have to worry about snakes slithering into our homes and our beds to surprise us in the night. The walls of our homes are pretty solid barriers. But phones, our primary portals to this increasingly incomprehensible madhouse we are mired in, we leave wide open. At any time during the night something terribly frightening could make it's way in. These are the challenges that we face in our lives, laughable as they are by contrast...
Anyway, don't sleep; there are snakes.