Interpreting the Oracle: Neuroscientist Sidarta Ribeiro explores history, biology of dreams


Everyone sleeps, which means everyone dreams — but not everyone remembers those dreams. Neuroscientist Sidarta Ribeiro proved this point at the outset of his lecture, when he asked his Chautauqua audience to raise their hands if, surely, they sleep every night. But when he asked how many remembered the dreams they had while asleep, only half raised their hands.

Ribeiro, whose research focuses on memory, sleep, dreams and psychedelics, is the founder of the Brain Institute at the Federal University of Rio Grande do Norte, Brazil, and the author of The Oracle of Night: The History and Science of Dreaming. His lecture Tuesday in the Amphitheater was part of the Chautauqua Lecture Series Week Six theme, “After Dark: The World of Nighttime.”

We know much more about sleep than we do about dreams; humans go through four to five full cycles of sleep each night. Some, but not all, of those cycles feature dreams, and it’s the REM cycle when we dream the most, Ribeiro said. But thanks to the prevalence of electric lights, and then television screens and the internet in the palms of our hands, humans are sleeping less, which means we’re dreaming less.

“What we know is that we are sleeping about two hours less than people did 100 years ago,” Ribeiro said. “It depends on the age group. It depends on where you’re living. But overall, it basically means we are getting poorer and poorer sleep as we progress into the 21st century.”

Less sleep, essentially, means less of a chance for the REM cycle — the last cycle of sleep and dreams — to kick in. And what happens to people’s lives when they do not dream? We know that dreams are important in the history of humanity, Ribeiro said. Not just important, but essential. He traced stories from the earliest texts in Sumer, Mesopotamia and Egypt, all pointing to the centrality of dreams at the start of civilization. The Bible is filled with premonitory dreams, but they’re not limited to the Judeo-Christian tradition, Ribeiro said.

“People knew, in the antiquities, that dreams cannot be taken at face value; it’s not as if you have a dream and the dream is exactly what happens or tells you what to do, because you need to interpret dreams,” he said. “Sometimes they can be very direct, but sometimes they are very metaphorical.”

As the age of antiquities neared its end, philosophers attempted to classify dreams into two categories: A “regular dream” that references the past, and a “special dream” that refers to the future. A clear example of “special dreams” is Calpurnia, the wife of Julius Caesar, immortalized by Shakespeare, who dreamt her husband would die in a pool of blood — and her husband’s own dream.

“Caesar had a very different dream,” Ribeiro said. “He had a dream in which he would fly through the skies across the clouds and then go all the way up and meet Jupiter himself. … Jupiter greeted him warmly and said, ‘You’re now with us.’ And he felt empowered by this dream, so he didn’t pay attention to his wife, and he did go meet the senators, and we know what happened. Her dream came true in detail.”

Both dreams were premonitory, Ribeiro said, and noted he could go on for hours with examples of such dreams, from every single culture. But things started to change in the past 500 years, as “capitalism and science intertwined” first in Europe, and then everywhere Europe had influence.

“This role that dreams had to serve as some sort of insight into the future, even though it was somewhat fuzzy, somewhat noisy, somewhat needed interpretation — but nevertheless, an insight into the future — was substituted by science,” Ribeiro said. 

People didn’t need dreams and premonitions; they needed mathematics and meteorology.

“Dreams were completely neglected, and became actually complete nonsense,” he said. 

This is why we know more about sleep than we do about dreams — sleep, after all, is a “solid, scientific object.” But, Ribeiro stressed, this was only the case in Western cultures. He cited various African cultures, Indiginous communities in North America, and the Xavante people of his native  Brazil, who all understand dreams as spiritual voyages.

“For example, voyages to meet your ancestors, in which you can go and ask for council, in which you can go and ask for inspiration, for new ideas, for new names, for new songs, for new strategies,” Ribeiro said — bridging the dreams looking back with dreams looking forward, with inspiration from those dreams having real-world impacts.

The Xavante were combating occupation efforts by the Portuguese and then Brazilian governments during the 19th and early 20th century; in the 1940s an Xavante elder had a dream.

“We cannot fight the white man,” the man advised, based on his dream. “We need to make peace with them. We need to become friends with them.”

So the Xavante shifted their strategy, Ribeiro said, and they are now among the strongest Native people in Brazil because of it.

Beyond the artistic, metaphysical and historical influences of dreams, Ribeiro said science itself owes inspiring breakthroughs to the phenomenon — from chemistry to the periodic table of elements. 

“It’s interesting to see that even though science didn’t have a place for dreams for a long period of time, dreams always had a place for science,” he said. “They were always helping science throughout.”

After all of this, Ribeiro asked, could there be a plausible, evolutionary narrative to make sense of dreams? Dreams — at least at this point in our understanding of physics, he said — can’t actually predict the future. 

“Therefore, we need to come up with — if not a new physical explanation for things — we need to come up with some biological explanation,” he said, and maybe then some sense can be made of dreams.

Going back 4 billion years, to the beginning of life on earth, all biological organisms have a circadian rhythm — from the ones with just a single cell, to humans.  

“This means that this alteration of day and night is perhaps the most prevalent selective pressure, which means that all forms of life had to adapt to this,” he said. “They could not go against it. They had to go with it.”

This is true from jellyfish to humans — and all animals experience what is called “quiet sleep.” But there’s another kind of sleep, called active sleep, otherwise known as the REM cycle. Research has shown that even flies might experience active sleep; Ribeiro’s own lab has proven that octopus do. But those REM cycles are short, very short, compared to that of humans, whose cycles last 40-50 minutes. (The REM cycle for a platypus, however, is more than an hour.)

At the beginning of mammalian evolution, Ribeiro said, the focus was on survival. So the notion that dreams somehow predict the future likely evolved during the period in which all cognitive powers were dedicated to surviving. It has to do with memory reactivation, he said, and when we sleep, that’s exactly what happens.

“Threat simulation theory  says dreams evolved as a way to warn our ancestors about impending threats,” Ribeiro said. “By reactivating memories of those threats, this allowed us, our ancestors, to prepare for the future. … Whatever is happening to you now has direct consequences for tomorrow. And if you dream about that, you are simulating outcomes.” 

So the Oracle of Night evolved under harsh, but simple conditions — kill or be killed, eat or be eaten. But in the modern world, “when you have thousands of little problems, the dreams reflect that. And they often don’t make sense as a whole.”

As history progresses, and as humans evolve, we begin to share our dreams.

“If mammals are the animals that have the most dreaming, we are the only animals, as far as we know, that can share our dreams,” Ribeiro said. “I also have a little bit of suspicion that this may not be true. … (But) what we know is we can do it. And there’s no reason to believe that our ancestors 300,000 years ago were not doing this. Very likely, they were getting together and sharing their dreams around the fire.”

This is what truly, as far as we know, sets us apart from other mammals. A pet dog may always know to expect their human home at 6 p.m., but only humans can close their eyes — Ribeiro had the audience try this — and picture their best friend from the age of 5, to immediately picturing their plans for Thanksgiving.

“We can travel within our memories towards the past, towards the future. We can come up with stuff that never existed, and this is so easy that we can still do this as we talk to people and drive a car somewhere,” he said.

This is because the same parts of the human brain responsible for dreams are responsible for daydreams; so, as prehistoric humans developed stronger relationships among their families and communities, and the concept of death and loss developed as well, dreams took on a new meaning.

“Imagine back in the Paleolithic era,” he said, “(and you dream of a dead relative). This can only be interpreted as evidence of that person being alive. And many people have proposed … this was the beginning of the belief in gods.”

Science shows that sleep is when the brain detoxifies and heals, improving cognition and ridding the organ of malformed proteins. But it’s only been in the last 12 years that science has been able to show that dreaming is beneficial for a person’s cognition. And this delay in science, and the fact that both sleep and dreaming have been neglected in Western culture, has “tremendous impacts at the ideological, social levels,” Ribeiro said.

“When you sleep poorly and dream poorly, you get all sorts of problems the next day,” he said. “You have cognitive problems; you can’t remember what you know. You can’t learn new things. You have bad emotional regulation. You become cranky, grumpy, difficult to deal with, and this is like a social snowball.”

Down the road, a lack of sleep and restorative dreams can lead to diabetes, depression, cardiovascular disease and, eventually, Alzheimer’s disease.

“We know that we have a problem in the world,” Ribeiro said. “There’s more people dying from suicide than homicides. People are feeling despair. People are feeling disconnected. Depression is rampant, even in countries that are developed and rich.”

There have been endless technological advancements, Ribeiro noted, but humans can’t solve starvation, or pollution, let alone contemplate the universe. He argued that this paradox may be linked to humanity’s abandonment of sleep and dreams.

“If we knew how to sleep and dream properly and to use those dreams, to share our desires and fears, could we be more empathetic? Could we be more resourceful? Could we be more creative? Could we be more intelligent and understand that the problems that our ancestors had are solved?” he said. “… If we’re just able to increase our ability to love and to decrease our ability to compete, we may actually survive ourselves.”

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The author Sara Toth

Sara Toth is entering her fifth summer as editor of The Chautauquan Daily and works year-round in Chautauqua Institution’s Department of Education. Previously, she served four years as the Daily’s assistant and then managing editor. An alum of the Daily internship program, she is a native of Pittsburgh(ish), attended Gannon University in Erie, Pennsylvania, and worked for nearly four years as a reporter in the Baltimore Sun Media Group. She lives in Jamestown with her husband, a photographer, and her Lilac, a cat.