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Emily Silverman

You're listening to The Nocturnists: Conversations. I'm Emily Silverman. At the height of the pandemic, we at The Nocturnists were struggling to talk about COVID in a way that felt fresh. So we decided to ask healthcare workers to send in their COVID dreams. We had somebody send in a dream about the floor being covered in ants, and trying to vacuum up the ants, and they just kept coming and kept coming. We had a story about a woman who found herself on a beach searching for her brother. And all the people on the beach were holding strings that disappeared into the horizon, which she thought were kite strings but turned out to be IV poles. We had somebody who dreamt that they were in a car accident, and then time slowed down and they watched the entire accident unfold in slow motion, with the pieces of glass flying through the air. It was really one of my favorite episodes of The Nocturnists that we ever made, and part of the reason why is it allowed us to dive into the subconscious of health care workers and explore what the pandemic was doing to us in a different way. If you want to take a listen, it's Stories from a Pandemic: Part II, Episode 4, and the title of the episode is “Dreams and Nightmares”.

So as you can tell, I've always been really interested in dreams. Which is why when I received this book, The Oracle of Night, I immediately picked it up. The author of the book and today's guest is Sidarta Ribeiro, a founder of the Brain Institute at the Universidade Federal do Rio Grande do Norte in Brazil, where he's also a professor of neuroscience. He received a PhD in Animal Behavior from The Rockefeller University, and he's the author of The Oracle of Night: History and Science of Dreams.

What I found inside that Sidarta’s book is this incredibly comprehensive exploration of what dreams are and what our relationship to dreams is, as human beings. He talks about where dreams started, walking us all the way back to antiquity and how they show up in old texts and cultures, and the importance of dreams and dream interpretation in older human societies. He talks about our modern lifestyle, and how that hinders our ability to sleep and dream and harness the power of dreams. He talks about dream interpretation as a communal activity that can be really powerful.

And that's not even starting to talk about the neuroscience in this book, and his beautiful descriptions of the brain and the electric activities in the brain and the neurotransmitters and the hormones and everything that comes together and synchronizes to produce this powerful and mysterious process called dreaming, which is such an important function for mental health and physical health and also human thriving and flourishing.

It also made me think about sleep deprivation among medical residents. And I have to admit, I had some stirrings of anger as I realized, for the first time in a while, how much sleep I missed out on as a resident. And I've been doing some writing about that on the side. So this book definitely inspired me to dig into my own emotions and sift through some old feelings about medical training and sleep.

I was thrilled to have the opportunity to speak to Sidarta about his book. We zoomed from his apartment in Brazil and I was here in San Francisco. And there was this super high-pitched whistle from the wind outside his apartment window, and somehow our editor, Jon Oliver, was magically able to make it disappear. So thank you, Jon. And it's really a great conversation. We cover a lot of ground, ranging from the historical to the scientific to the spiritual. So I'll leave it there. I’m really excited to introduce neuroscientist Sidarta Ribeiro. Enjoy!

I am sitting here with Sidarta Ribeiro, Sidarta, thank you so much for being with me today.

Sidarta Ribeiro

Thank you for inviting me. It's a pleasure.

Emily Silverman

I've always had a very rich dream life. But I had never read a book about dreams. So I loved this book because it helped me understand aspects of my own experience. And I love the way that you blended history and science. And so I'm just really excited to talk to you about the book today.

Sidarta Ribeiro

Wonderful. And thanks.

Emily Silverman

So if you don't mind, I'd like to open with a personal anecdote of yours from the book which is called “Narcoleptic in New York,” where you tell the story of arriving in New York City to do research. And it's winter time. And suddenly you feel this impulse to sleep all the time. And it lasts for a while. And then when spring comes, the impulse to sleep goes away. So tell us what happened and what that felt like.

Sidarta Ribeiro

It was January ‘95. And I arrived in New York City to begin my PhD studies at The Rockefeller University. And it was snowing like I had never experienced before. And I was coming from sunny Brazil. I had just finished my master’s and I was one semester late for my graduate program because I was finishing the master’s. So when I arrived, I arrived in a situation when my colleagues were at high academic speeds, discussing several papers a week in the seminars and going to amazing talks by huge scientists. And I found myself lost–lost in terms of the science that they were talking about that I was not aware of, but also lost in English, which really was a huge surprise because I learned how to speak English early on. And still, even though I was very confident about my language abilities, I just couldn't really understand what people were saying. I had this distortion of perception. I could not understand well. I could not express myself, certainly.

Then I said, ‘Well, I'll go back to the laboratory, just work hard at the bench. I know how to do that. I'll show my worth.” And I would go to the lab and sleep, sleep like crazy, you know, go to the meeting room and go to the couch and sleep. And then it got really embarrassing. I decided to let me take a nap at home every day. And then it was like two naps and then three naps and then the whole day. And I was resisting and resisting and struggling and feeling embarrassed by the whole situation.

At some point I surrendered. I said, “Okay, if I need to sleep sixteen hours a day, let it be,” and I surrendered myself to sleep and to dreaming. Then it was already February. And I started this huge epic dream, sometimes quite scary and involving social anxiety, sometimes quite lonely involving being in New York alone, completely alone, like being in the city with not a single person to be seen. And then at some point they became lucid dreams—dreams in which one becomes aware of being in the dream.

And then, boom, between March and April, I just went out of that situation of inadaptation and went to a situation of adaptation. Things started to go great in the lab. I actually had results that became the core of my thesis years later, the things were great at the seminars, I could understand everything, I could talk to people and think better, I had a network of collaborators already established. And I had a network of amazing friends that are among my best friends to this date. So when I got out of it, I realized that my body was not trying to sabotage me, but rather to help me adapt. And I needed that time offline, to get to that point.

Emily Silverman

Such an interesting story. And it reminds me of this novel that I'm in the middle of reading, that's called, My Year of Rest and Relaxation. And it's all about a woman who decides that she's going to do nothing but sleep for one year. And so I’ll put the link in the show notes, and maybe I'll send you a copy.

Sidarta Ribeiro

Please do. Thank you.

Emily Silverman

So this raises the question, what is sleep?

Sidarta Ribeiro

So sleep is one of the two main states that animals can be in. They can be in waking or they can be in sleep. And it's a very old thing that began hundreds of millions of years ago. But sleep is also a multiplicity of phenomena. It has different phases, it has different parts. And when we talk about dreams, we’re mostly interested in the last phase of sleep in a sleep cycle, which is called rapid eye movement sleep, or REM sleep. During REM sleep, we're very much closed to the outside and very much open to the inside, to the inner world of symbols, representations, images.

Emily Silverman

Walk us through the phases of sleep, because as you said, it has many parts–there's almost like an anatomy of it–and tell us how that works.

Sidarta Ribeiro

When we go to sleep, let's say if we go to sleep around 8 or 9PM, so regular entry points for sleep, we will go into a consecutive succession of phases that comprise stage one, very brief, in which there's some dreaming going on, and usually some images, sometimes, that reflect anxiety or reflect the residues, things that happen during the day. Then we go into phase two, which is also brief, a few minutes. You may still be dreaming, but sometimes you start having those moments of no image at all. And then in phase three, which we call slow-wave sleep, we will actually experience little dreaming, sometimes no dreaming at all. And when dreaming is happening it's often not made of strong vivid images, but rather of thoughts and preoccupations, things that we need to do in the waking life. And then we go into the fourth stage, which is rapid eye movement sleep. This is a full cycle of sleep, and we undergo four or five of those per night, typically. But as the night progresses, the slow-wave sleep phase becomes shorter and shorter. And actually, at the end of the night, we're not even getting there, we're going from stage two to four. And stage four REM sleep becomes longer and longer and longer. And as we progress through the night, the dreams become more complex and more metaphorical, more allegorical, full of associations, which often bring us to great insights into our desires and fears and challenges. But there's an art of dreaming. There's a very old art, with many different traditions that teach us how to remember dreams, how to record them, how to share them and use them.

Emily Silverman

I want to get into the art of dreaming in a bit. But first, just staying here in the science, during sleep, what parts of the brain are activated and deactivated?

Sidarta Ribeiro

When we are ready to sleep, when we close our eyes and put ourselves in a rest situation that allows us to begin the process, we will see the rise of melatonin, produced in the pineal glands, which will tell our body that it's time to sleep. So once we go into sleep, we see this shutdown of incoming sensory information from the telomere cortical circuits. And we see more importance of the intrinsic circulation of electrical activity in the telomere cortical loop, but also circuits that comprise the hippocampus and other regions that comprise the so-called default mode network.

This default mode network is a series of brain regions that are interconnected, that are functionally engaged when we are dreaming, but also when we are daydreaming, when we are producing narratives, remembering things that happened, like bringing back episodic memories, but also making things up in imagining situations–fiction, basically. A lot of what goes on has to do with the variations in the negative feedbacks of different neurotransmitters. For example, acetylcholine and dopamine and noradrenaline and serotonin, on one hand, and acetylcholine on the other side. We're talking about several brain regions that are very deep and very old, that control the onset of the different sleep stages. And at some point acetylcholine takes over, and norepinephrine and serotonin will be shut down. And dopamine will have a slight increase and this is the beginning of REM sleep. How the different neurotransmitters interplay to generate memory consolidation, the dampening of negative emotions, memory triage, forgetting a lot of stuff, remembering some important stuff, memory restructuring, gaining insight, creativity, all those different aspects of memory processing during sleep have to do with those changes in neurotransmitter levels.

During REM sleep, there's a lot of synaptic selection, so many synapses get washed away and destroyed, including recently-formed synapses. But some get to be enriched and kept, with long term consequences for the process of memory representation. But it would be fair to say that some of the most important hallmarks of dreaming have to do with, one, lack of norepinephrine and serotonin during REM sleep, which tends to make the propagation of electrical activity a little noisier and therefore able to create new solutions, new paths, but also with the deactivation of several regions of the frontal cortex, which will have an impact in our criticism of situations. So when we're dreaming, we're often confronted with quite bizarre images. But we don't wake up and say, “Oh, this is impossible.” Sometimes this happens. But most often we don't have a strong criticism, we just accept things as they show up. Part of this is because some of our prefrontal cortex areas are deactivated, and we therefore have less ability to consider something to be unacceptable or not to be believed. And this flexibility gives dreams a huge creative potential because, since we do not have this strong censorship, we are able to consider perspectives that would normally not be considered. And one thing I argue in my book is that this is part of the reason why all the ancestral cultures, as well as many current cultures, considered dreaming a very sophisticated way to navigate the future.

Emily Silverman

Wow, there's so much to unpack there. And I want to ask you about memory, I want to ask you about learning, I want to ask you about creativity, because each one of those, I feel, could take up an entire hour. So let's start with memory, if you don't mind. There was something you just said about memory triage. And I had never heard that phrase before. And that's so interesting. There was a line in your book that said, “Dreams exist not just for remembering, but for forgetting.” And some of the language that is used in your book around the hippocampus reminded me almost like a computer where certain memories are wiped and installed and then upgraded into the cortex, for example. Tell us about what is happening with memory while we're asleep.

Sidarta Ribeiro

Most of the stuff that happens to us during the day is not memorable. If I ask you, “What did you have for breakfast today,” you probably remember. But if I asked you to go back for two days, unless you always eat the same thing, you will say, “I have no idea.” That's not in our log anymore.

Emily Silverman

Right.

Sidarta Ribeiro

So we need to basically forget a lot of stuff every night. And sleep has a central aspect in doing that. There are several mechanisms that contribute to us forgetting the stuff that does not need to be remembered. Then we need to keep some things, and sometimes keep them forever. And we need to be able to sort them to give different priorities to the different memories that we acquire. And there's a lot that's going on in cells and neurons that in the end have to do with this selection, with this tagging, what matters and what doesn't matter. And there are several subtle mechanisms that can affect that. If you just tell people that some stuff that they have just learned is irrelevant, that alone may trigger very selective forgetting.

Then there is another aspect, which is sometimes there's no memory in your memory database, what Freud would call the unconscious, that really can solve your problem. So you need to put some new idea together based on pieces of old ideas. This is at the core of creativity. And the conditions, especially the neurochemical conditions and the changes in functional neuroanatomy that occur across the sleep cycle, they will favor this process of bringing new memories to the surface. And the surface is actually the surface of consciousness, because when you wake up, and you have the idea in your mind, you can implement it in real life. And that's why I said this is the full art of dreaming–to use the dream to do things. So many inventors, many artists, many scientists used, and still use, dreams as a source of creativity for good reason. Because the brain is freer from the constraints of the waking life and can produce new solutions.

Emily Silverman

In pop culture, you hear a lot about the conscious mind and the subconscious mind. And what I'm hearing is that there's a conversation happening between the conscious and the subconscious, and dreaming perhaps surfaces some of the things that are going on in the subconscious. Is that a correct way to think about it?

Sidarta Ribeiro

Freud and Jung were amazing observers of human nature. And they really produced an amazing corpus of evidence that needs to be considered by neuroscience. Part of what my book is about is to defend that and provide evidence. We have a very small fraction of the mind that is conscious. Then there's a larger fraction of the mind, perhaps, that is in what people call the subconscious. And most of the mind is unconscious. All the memories that we gathered in our lives that we're not conscious of now are by definition unconscious. So if you have a dream with people you never met in the city you never visited, this is possible, because we have visited many cities and have seen many people and the combinations of that can be used to produce images that we can experience every night.

Emily Silverman.

As I hear you talk, it makes so much sense to me that sleep and dreams would be a useful tool for creativity, turning off the critic, turning off the sensor, opening yourself up to possibilities, loosening your associations. And in the book, you have some examples of great minds who have had epiphanies in their dreams or in their sleep. Do you have a favorite example of that?

Sidarta Ribeiro

Well, I always like to tell the story of Salvador Dali, because he was so attached to this as a method–allow himself to doze, drop a heavy spoon, and then use that moment of inspiration and using that to be the prime of a full painting. This is a very known example. But there are many examples in science as well. And I think they're all quite beautiful. I think it's tremendously interesting that we all had to learn the periodic table in high school. So it's something that everybody with a certain degree of education met. So it's something quite distributed around the world. And it came from a dream that Dmitry Mendeleev had. He had the problem–the dream works well when you have the problem well formulated–he already had the problem. He was looking for an arrangement of elements that could produce the properties, the chemical properties, that were known, and he knew that they should be ordered. But he didn't know exactly which solution would be the solution. And I think this is one of the most powerful effects of dreams is to allow things to settle, and coalesce into an image that can summarize the problem and the solution–importantly, the solution.

Emily Silverman

I love what you said about how he already had the problem. There's a friend of mine, who always tells me to ask the universal question. If I'm chewing on an idea, or there's something I'm trying to figure out, she always encourages me to actually formulate a question and put it into words and then put that question out. And now that I listen to you speak, I see why that makes sense. Because it's prompting, perhaps, the solution to arise from within. Can we talk about sleep and learning? Because learning is a type of memory. And I know there's different types of learning. But how does sleep help us learn?

Sidarta Ribeiro

Learning is the adaptive change of your memory collection. You have a set of memories, and they allow you to live. But when you change them, and if you change them to your benefit, then we call this learning. And there are many ways in which you can change your memories. You can change them by forgetting stuff, you can change them by adding stuff to pre-existing memories. You can change memories by acquiring new memories that are at first unrelated to other memories. But as time passes by, they need to be integrated. And sleep has a lot to do with that. Some parts of sleep are very good for some kinds of memories. So for example, declarative memories are stuff that we can describe names of people, events, tell stories and all that, that involves the part of the brain that we call the hippocampus. They can be greatly benefited by having long episodes of slow-wave sleep. Procedural memories, memories of riding a bicycle, capoeira, practicing kung fu, the stuff that you do, but you don't necessarily need to describe in words, these memories are tremendously helped by REM sleep. I'm not saying that this is like a complete dichotomy. I mean, both sleep phases contribute to both kinds of memories, but there's a distinction to be made there. Also, emotional processing depends a lot on REM sleep. If you are sleep deprived, that means getting deprived mostly of REM sleep, which means waking up less patient, more easily frustrated, more cranky. So when we see that people wake up and they are in a bad mood, it's usually because they got deprived of the opportunity to dampen the negativity of the previous day. And this is why it's an emotional snowball to be sleep-deprived throughout consecutive nights, which I think is a topic of interest for your audience, right?

Emily Silverman

Well, I'm glad that you brought up sleep deprivation, because part of the process of becoming a physician in America is putting yourself through residency and part of a lot of residencies is this culture of sleep deprivation. I did my residency in Internal Medicine. And for many months of my residency, I worked 28 hour shifts every fourth night, for weeks at a time. So, basically, every fourth night I would stay up all night, I wouldn't sleep. And then I would finish the shift and then go home and try to nap a bit during the day. And then the cycle would repeat every four days. And by the end of doing this for weeks, I felt just physically ill. I know that for some people it doesn't bother them as much, but most people who I speak with really do not respond well to that kind of sleep deprivation. So that begs the question, why are we doing this to our doctors in training? Why are we putting them through sleep deprivation?

And some of the voices that defend this practice, argue that sleep deprivation in this manner is important for learning, actually. And what they say is that when a patient comes to the hospital, and they're sick, let's say they have sepsis, that the first 48 hours of that patient's hospital course are extremely important to witness, to watch it unfold, and to see the impact of your decisions. And that if you are to take a break during those first 48 hours to sleep, that somehow that hampers or hinders the learning process. That has never felt true to me. And I've always intuitively felt like the risks of sleep deprivation far outweigh any benefit in that scenario. But I'm curious how you would speak to somebody who is making this argument.

Sidarta Ribeiro

I think it's an insanity. And I think it has to do, first, with the surrender to the system as it is, second to a narrative of steel character and resistance, a myth of invulnerability of doctors, which I don't think is in the interest of anybody to continue. The science of sleep is solid enough that we know for a fact that any professional–any–will be impaired in reasoning, in cognitive abilities, in emotional reactivity after being sleep deprived. I don't see anything there worth defending.

I think it's about time that medical doctors are treated with respect and treat themselves with respect, so that they are at their best when they're doing their important job. And we know very well that these things work in teams. So it's not true that this one person will be there following one patient that needs 48 hours of full rotation. It doesn't work like this at all, this person will be there, as you said 28 hours in a row, seeing many people increasingly with less attention, less patience, less empathy. So I think it has to do with treating medical doctors like persons, not machines.

Emily Silverman

What are some of the negative health consequences of sleep deprivation? You talked a bit about emotional dysregulation and blurry cognition, but in the book you actually mentioned, like, specific diseases that are associated with sleep deprivation.

Sidarta Ribeiro

In the short term, if you’ve got sleep deprived this one night, the next day you have cognitive problems and emotional problems. But over the course of days and weeks and months, this can evolve into depression. This can evolve into diabetes, cardiovascular disease, and, down the road, Alzheimer's disease, because sleep is tremendously important to detoxify the brain from its own toxic metabolites, like alphabeta amyloid protein.

Emily Silverman

I think I saw a headline in JAMA recently about a new study that proved that during sleep there's almost like a washing of the brain that happens.

Sidarta Ribeiro

Absolutely. This has been known for about eight years. It's research that began in rodents and then evolved into human research. Now, it's very clear that if we want to live a long healthy life and not go into dementia or neurodegenerative disorders, we need to have good sleep on a continuous basis. We cannot sustain the practice of sleeping very badly, dreaming quite little, remembering nothing and think it's going to be of no consequence to individuals and to society.

Emily Silverman

When I was a little girl, I had an experience where I was falling asleep and I heard voices. Actually, it was one voice. And it was an auditory hallucination. The voice sounded like another person's voice, it sounded extremely real. And it was saying my name and it was asking me questions. And it scared me. I had never experienced anything like this before. And I got out of bed and I ran into my parents room. And I told them, “There's someone in my room!” And my dad came out, and he looked around the room with me. And of course, there was nobody in the room. And then, years later, I grew up and I learned about this idea of the hypnopompic, or hypnagogic, hallucinations. So in other words, hallucinating just on the edge of sleep, so as you're falling into sleep and as you're coming out. And since then it's happened to me again and again. It's not every night, but occasionally I'll hear something or I'll see something. One time I even saw a man standing in my room. Talk to me about dreaming and psychosis.

Sidarta Ribeiro

If we pay enough attention to our dreams, we will all have this experience of the twilight zone. When we are having a full fledged dream, then we are not so scared because, oh, it's a dream, we explain it out. Which is not the attitude that our ancestors had at all. They actually took them very seriously. They said, “Whoa, this person is in my room, but it's not in the room. Therefore, it's a spirit living somewhere else.” And this is actually the very roots of the religious experience. This is a proposal by Nietzsche, by Durkheim, in the 19th century, and I think it's quite true. I remember as a child having very similar experiences. And sometimes, when I'm very tired, I go to sleep and I have very strong auditory hallucinations. And it's not a different situation from the dream, except that it's happening during the transition. And we can think in that way that psychosis is an invasion of dreaming into the waking life.

And this is something that was believed in the 19th century by the founders of psychiatry, like Breuer, Kraepelin, and Freud himself. They didn't agree on many things, but they agreed on that. And that was common sense in medical school until the 1950s. It's only in the 1950s, when the solution for a psychotic patient became, not talking or listening to that person, but bringing drugs in, that people started to think that perhaps we don't need to address those images at all. Let's bypass the images. Let's go to haloperidol and get rid of that. And now we know it's way more complicated than that, because one thing is to medicate the patient so that the community around the patient does not feel threatened anymore, and the other thing is to actually help that person realize his or her full capabilities. And just drugs won't do the trick, even if they're smarter drugs. I mentioned haloperidol because we now know that REM sleep is tremendously dependent on dopamine. So the notion that dreams invade the waking life when people are having a psychotic episode is a notion from the past, the origins of psychiatry, that are now on the table in very strong scientific research being performed in that direction right now.

Emily Silverman

For those people who are having symptoms smack dab in the middle of the day while they are wide awake, what is some of the evidence or thought about dream worlds intruding into waking life? Is there research that's been done on that? And how are we thinking about harnessing our knowledge about sleep and dreams to treat people who are having these symptoms?

Sidarta Ribeiro

So part of the research is preclinical. For example, if you have high levels of dopamine in a transgenic mouse, the animal will show electrophysiological patterns during REM sleep that are closer to those of waking and vice versa. So there's an approximation of those patterns. When we think that drugs that inhibit the dopaminergic system can prevent psychosis to manifest some of its symptoms, it's also going along that direction. And then we have to think of the evidence that people that have a lot of metacognition can actually learn to live with these hallucinations. And this is something that was beautiful portrayed in the movie, A Brilliant Mind. So John Nash could actually look at the characters that would show up in his psychosis episodes and say, “Oh, I don't want to talk to you, I don't believe in you, we don't exist.” So we are able to even get to that level of denying the inner reality so that we can live better the external reality.

So, in that sense, we can say that in a psychotic episode what we have there going on is a dream that is becoming untenable, a dream that is causing frustration and suffering and that needs to be dampened. And how is the person to dampen that? Through medication, through yoga, through breathing, through concentration, through praying–there are multiple ways of addressing it. And I think that, in the end, if we see it that way, we tend to begin to remove the stigma of having this particular condition. I think we need to look into the future in which every kind of mind has its place on this planet. And we also should understand that people that don't seem adapted to the current contemporary society were probably the most adapted many thousand years ago. This kind of disorder was actually a great benefit and honor. And many cultures to this day still believe that people that have this tendency are actually honored and favored by the gods and goddesses. So we need to be very respectful and, at the same time, discover how to help people so that they can live better, and so that we can live together.

Emily Silverman

It sounds like studying sleep and dreams could unlock some of the secrets of mental illness and other aspects of being a human. But the study of dreams has been somewhat controversial. In the book you say, “In the second half of the 20th century, dream research came increasingly to be considered unscientific.” Tell us about the scientific community and its relationship to the study of dreams.

Sidarta Ribeiro

I think that for about 50 years it was really a dead end for a scientific career to investigate dreams. Some very resilient people continued to do so. But many people had to leave the field or change topics of research, because it was harder and harder to have a serious conversation about dreams in the biomedical context. One of my scientific heroes is Robert Stickgold, in Harvard, and he was among the few people that were able to change the course of that situation. So in the late 90s, and early 2000s, Bob Stickgold was able to bring the study of dreams back into respectability, taking those studies to the highest possible level in terms of publication impact, and also how it reached the media. And then a shift began.

So, I would say, in the beginning of the 21st century neuroscience and psychology began to look at dreams in a different way. And now they are really hot topics of investigation. Not just regular dreams, but lucid dreams became quite important. And now people are really investigating these states as a frontier in neuroscience and psychology, and not as a cesspool of frustrated scientific conditions. In the 50s and 60s, I think there was a big divorce between, on one hand, psychoanalysis, and, on the other hand, neuroscience, and I think that this is what is about to end. Now we're starting to understand that we need to bring together the knowledge accumulated, rather than choosing one particular field versus another.

Emily Silverman

Occasionally, I have happy dreams, dreams about flying and meeting people who I love. But mostly my dreams are filled with anxiety and fear–dreams about being late, being lost, being threatened by a person or an animal. Are most dreams in humans positive or negative?

Sidarta Ribeiro

Studies from around the world indicate that above 50% of the dreams that people have tend to be of negative contents. But that doesn't mean that it's all nightmares. It's this whole range of tones of anxiety. But the good news is that nearly half of the dreams are not like that. And they have different contents including very pleasant contents. But we have to remember that dreaming is something that began to evolve hundreds of millions of years ago in the mammalian lineage and perhaps even earlier. It's a neurobiological process of trying to simulate potential future scenarios based on the memories that have been already acquired. So dreams have to do with solving the problem of life on a regular daily basis. For all animals, except humans and those that we domesticate, every day is the day in which one can die, one can kill, and one may mate. So those three Darwinian imperatives–to kill, not to be killed, and to mate–are governing dreaming activity in mammals. And this is still true for us. But on top of those three huge problems, we have dozens, hundreds of small problems, that each of them carry a certain amount of anxiety. And often our dreams are just a collection of that, reflecting that. But when we have a major single problem in our lives, dreams can become tremendously cohesive and meaningful and impactful.

Emily Silverman

You talked about how dreams are like a simulator–it's this abstract space where we're able to anticipate events, different journeys, different outcomes–how dreams can help us prepare for the following day, help us navigate, as you say, the problem of life. But then there's also this idea that dreams don't just help us predict the future, but that they can predict the future. In the book, you talk about examples of people who had dreams warning them that they were about to get an illness. And the dream preceded the first clinical symptom by weeks, months or even years. In woo-woo communities, there's this idea of the pre-cognitive dream, and that's been extrapolated into sci fi movies like Minority Report, where you dream something and then days, weeks, months, even years later, the thing happens. Where do you fall on that? I mean, obviously, that's a very spiritual question. But can dreams predict the future?

Sidarta Ribeiro

I wrote this book, because as a biologist, I believe that we can explain most, if not all, such reports with what I call “the probabilistic oracle.” So dreams are a neurobiological machine to predict the future. But they do so in a probabilistic manner, they therefore would not be able to really predict the future in a deterministic sense, because that would require not new biology, but new physics, and we don't have it. Maybe somebody will, will go there, but we're not there. And if we are to stick to the physics that we have, then this is likely an impression of determinism that comes from the exquisite ability of this probabilistic oracle to sometimes simulate what actually would happen, and it happens.

So for example, famous dream that Julius Caesar's wife had–Calpurnia. The night before his killing, she has a dream that the people in the antiquity called the prophetic dream, a dream that is literally exactly what happens. She dreams that Julius Caesar is going to go meet the senators and be stabbed to death. And she warns him, and he doesn't listen to her. And he goes to meet the senators and gets killed exactly the way she predicted. Now, did she really predict what would happen? If he had stayed home, would he have died? This is actually why it's important to interpret dreams, to be able to act upon the stuff that is going on, so that you can prevent that outcome if needed, or actually produce a certain outcome. It was not difficult for her to have that dream because he had been in conflict with the senators for years. There was a civil war that was produced because of his actions. And he had won the war, but he still had many opponents. So the dream was reflecting something that was quite probable to happen.

Sometimes people come to me and say, “Oh, I had a dream that does not fit that description. That is about stuff that I had no way of knowing.” And therefore a probabilistic neurobiological machine does not suffice to explain the dream. And what I respond is twofold. One is that I personally didn't have that experience so I cannot say that I know what the person is talking about. But then I say, “I trust what you're saying, but for this to become science, we need to be able to verify the prediction before the outcome.” I have proposed to different PhD candidates in my lab, over the course of years, that we may need to address that. There is a particular aspect of Brazilian culture, where I live–I live in Brazil–that would allow for that to be tested, because there's a betting game, a popular game in Brazil called the “animal game,” in which people bet money on specific numbers that represent specific animals. And this goes on and on–every day people are doing this all across the country. And there is this culture of having dreams with animals and then placing the bets. So if we were able to get the information of what are the bets based on which dreams and which animals before the outcome was publicized, we would be able to actually quantify whether there is any deviation from chance. My personal hunch is that there is no division from chance. I don't think that dreams can really predict the future in that deterministic sense. But I'm a scientist, so I'm open to evidence.

Emily Silverman

You mentioned lucid dreaming. In the book, you describe it as, “a state normally associated with the later stages of REM sleep moving toward the morning, when the body has already slept enough and so goes into a very special state in which there's little pressure to sleep, along with elevated stocks of releasable neurotransmitters, and abundant REM. It is at this moment, when the brain is dreaming vigorously but is already ready to wake up, that sometimes, almost miraculously, it wakes up into itself.” And I've had lucid dreams before. Again, not often, but sometimes. And while I was reading your book, I had some of the most intense lucid dreams of my life.

Sidarta Ribeiro

This is so cool!

Emily Silverman

Perhaps this speaks to this idea of auto-suggestion, you know, the more that you're reading about lucid dreams, maybe the more lucid dreams you have. But I'll just say I've had these experiences where I wake up in a dream. And I'm conscious and I look around. I remember one time I was in a train station. And this train station looked so real. I just remember thinking, like, wow, this feels indistinguishable from reality. And I remember thinking to myself after I woke up, like, I could never build or design a train station in my waking life. And yet, during my lucid dream, it was like I had invented this place, like, more from the bottom up than from the top down. Talk to us about lucid dreaming. What is it? How does it work? And when you measure brain activity during a lucid dream, do you see, like, the prefrontal lobe, like, switch on? Or is it kind of like a simultaneous awake and asleep? Or what is happening there?

Sidarta Ribeiro

Okay, those are great questions. And I really liked the way you describe the fact that you were able to have a very strong lucid dream as you read the book. I got feedback like this from many people, not just about lucid dreams, but dreaming in general. And exactly for what we just said– that if you talk about dreams, if you read about dreams, you think about them and what they mean to you–and all of us have old experiences in which dreams were important, most of us at least–then we can reconnect with that and they become more closer to the surface. Lucid dreams are, in my own experience, one of the most amazing situations one can experience in life. They are equivalent to navigating your own unconscious mind in a conscious way. And this is quite something. It can be tremendously pleasant and it can be, actually, more than pleasant. It can be numinous. It's the kind of experience that people before contemporary societies would consider as the finest hour, as the moment when you can really grow and expand and be fully yourself. So it's really something to be cherished, to be respected, to be learned. It's a skill. Some people are spontaneously good, lucid dreamers, but many are not. As to what happens in the brain, or what happens in the body, we know since the pioneering work of Stephen LaBerge in the late 70s and early 80s, and also Hearne at the same time, and then other researchers since then, in particular, Benjamin Baird, we know that most lucid dreaming is happening during REM sleep. And it's a very strong REM sleep with strong autonomic responses, with an enhanced degree of activity in various physiological parameters.

Now, in the past 10 years, some evidence surfaced that those dreams were happening when the prefrontal cortex was at higher levels of activity than would be observed during regular REM sleep. This evidence has recently been put into question by experiments showing that the increase in high frequency activity in the frontal part of the brain may be an artifact of eye movements. In fact, there are recent studies showing that they are artifacts of eye movements. But I think that we probably are seeing the beginning of a long fight rather than the end of a fight, because to show that most of it is an artifact doesn't mean that all of it is an artifact. And on the other hand, the people that never believed–like Laberge himself never believed in this increase in frontal activity–will point to other parts of the brain that show increases, even in the visual cortex, that can account for the phenomenology. So I would say we need to watch carefully as the studies unfold in the coming years, so that this is settled.

Emily Silverman

So for people listening who want to lean into their dream life, remember their dreams more, explore their dreams, or maybe even try lucid dreaming, what advice would you have for them about how to enrich their dream life?

Sidarta Ribeiro

With respect to regular dreaming, there are three important moments. The first one is when you go to bed, put yourself in a very comfortable situation to go to sleep, with no lights, with no sounds, with nothing to really disturb your sleep, and make a suggestion. Tell yourself in any way you like, “I will dream, I will remember, and I will record that dream.” Then, when you wake up in the morning–this is the most critical moment–you need to stay quiet in bed and let the memories come back to you. As you have more and more memories of the dream, keep doing that reconstruction process so that you eventually have a full dream to report. And then you write it down or record the dream. Don't move around. Don't talk to the people, don't do anything. Don't look at screens, just focus on the dream first. And then the third moment is bring it to other people. Talk about it with your partner, with your family, with the people you love, or your friends, bring it into your workplace or school place, make it a topic of conversation. But also try to understand how this new piece of the puzzle fits with all the other ones that you have been recording in your dream diary. So as you have more dreams collected, then things start to make more sense, not less. And you start to see the recurrences. As you said before, when you're anxious, a particular person will show up. Or when you're representing something that is bad or evil, a particular person will show up. This is a stable association. And if you have many data points, you will be able to see trajectories, you will be able to see the flow of things where you're going, in general, they produce a lot of insights. But I want to add a fourth aspect which is to try to bring the meaning of the dreams out of one's own perspective into the collective perspective. Because using dreams to promote cultural change and to promote adaptation was always in our lineage, a collective endeavor. It was always about sharing dreams, so as to coalesce unions among people so that people can act together on problems. And one of the main issues with our crisis in sleep and dreaming is that we are all individualized, and not making sense of things collectively. And this has a lot to do with our political problems. And so I would say, let's focus on rescuing the art of dreaming. But let's bring dreams to the collective good, rather than individualistic dreams.

Emily Silverman

I love that and I think that's a beautiful place to end. I have been talking to Sidarta Ribeiro about his book, The Oracle of Night: The History and Science of Dreams. This is a tremendous book. I've learned so much from it and just the act of reading it actually impacted my dream life. So if you are interested in exploring your dreams, maybe a good first step is to go out and get the book and read it. I'm sure it will open your mind to many, many aspects of neuroscience and spirituality and symbols and representation. Just such a rich work of art! And this conversation has been, too. So thank you so much for coming.

Sidarta Ribeiro

Thank you! Muito obrigado.