Instant Genius - The science of dreams, with Sidarta Ribeiro

Episode Date: May 29, 2022

Neuroscientist Sidarta Ribeiro speaks to us about what is going on in our brains when we dream. Once you’ve mastered the basics with Instant Genius, dive deeper with Instant Genius Extra, where you���ll find longer, richer discussions about the most exciting ideas in the world of science and technology. Only available on Apple Podcasts. Produced by the team behind BBC Science Focus Magazine. Visit our website: sciencefocus.com Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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In this episode, I talk to neuroscientist Sidata Hibero about the science of dreams. So obviously we can't talk about dreaming without talking about sleep. So I think this is the sort of obvious place to start. So as a neuroscientist, you know, what's going on in our brains and our bodies as we fall asleep? Our brains are very active when we are asleep. And the brains are doing different things across the night. So we usually have four to five full cycles of sleep at the begin with a dreamy-like state that then transits into something that is more like an image-absent situation,

with sometimes some thoughts related to regular life, chores we need to do. And then we go into full-blown, vivid imagery, that what we really call dreaming is what happens during rapid eye movement sleep. Of course, we can extend that notion to imagination during waking life, daydreaming, because the same brain regions involved in night dreaming are involved in waking dreaming. So you mentioned there are REM sleep. So I think that's something that a lot of people will have heard of, but they might not know actually what's going on in our bodies and our brains

when we're in this stage of sleep. So could you tell me about that, please? Yeah, this is what the French called paradoxical sleep. And why paradoxical? Because even though the body is very still, the brain is very active. And some parts of the brain they have to do with emotions, memories, and the visual representations of those are quite active. So when we are during REM sleep, and that I must say is for adults.

For children, it's more complicated. But when we adults are in REM sleep, we are very likely to be having a very vivid dream. And the name comes from rapid eye movement sleep, a discovery in the 1950s that children, and then, of course, it was seen in adults as well, move their eyes in very fast and strange manners during this particular sleep phase, as opposed to the previous phase in which we barely move our eyes quite slowly. And this is accompanied by this very deep form of sleep that is very restorative, very important for health, both at the level of the body at the level of the mind. But it's not enough to process all the memories of the waking life,

and especially the emotional memories. So we need to run sleep. We need this last phase of sleep in the cycle. And across the night, this distribution of states change. So as we go through the night, we have less and less of the non-dreaming sleep, the so-called slow-wave sleep, and more and more of the dreaming sleep, the REM sleep. So what's going on our brains when we switch into this stage of sleep? Yeah, there are major changes.

When we are in slow-wave sleep, we have sort of a battle between different neurotransmitters. Acetylcholine is being released. and sometimes periodically and with a decrescent frequency, noradrenaline or norapine is released as well as serotonin. When we transit into REM sleep, acetylucoline goes up, noradalin and serotonin go down, and dopamine actually goes up. And it has a lot to do with the beginning of REM sleep.

And dopamine is very important, because it allows for the brain to signal reward and punishment, for the brain to signal the outcomes of the actions. And dreaming has a lot to do with the simulation of outcomes of possible actions. How about the different regions of the brain, for example, the visual cortex? What's going on there when we're in this stage? The visual cortex is highly active, especially what we call association areas,

areas in the cerebral cortex that are more removed from the retina input. but most of the visual areas are interconnected and there's clearly a preference for visual experiences in most people's dreams. But of course you can have dreams of other modalities as well. We can have dreams that involve somesthesia that involved gustatory experiences or sounds, etc. And you can have all of that in one dream as well. But that is a very particular situation that is happening at this particular moment in the brain of that particular person. So it's quite specific.

Other areas are involved as well in dreaming, subcortical areas, regions, such as the hippocampus, which is important for the acquisition of new memories and for connecting those memories with preexisting memories. And the amygdala, which is important for us to tell the difference between positive, pleasant situation. and negative, aversive situation. So all of that is involved and engaged and active during REM sleep. But as important as those brain regions are, we need to talk about what's not activated during REM sleep, which has to do with its bizarness.

And this mainly involves regions in the frontal cortex that have to do with the inhibition of certain behaviors, with decision-making, with making choices and navigate the situations with criticism. So since many of those regions in the prefrontal cortex are deactivated during Renslieb, we tend to not be surprised or shocked by the crazy stuff that happens during Dream. So that's the sort of the theoretical bit. So that's all really fascinating and really, you know, really quite complicated.

But how do you study this? Do you put people in brain scanners when they're sleeping and that sort of thing? How did we find this out? Well, it's a combination of techniques in the 50s. A lot was done and since then and until today, a lot is done with regular electroencephalographic recording. So EEG is used. People have studied sleep and dreaming inside brain scanners. It's not a simple task because, of course, they're quite noisy and somewhat claustrophobic.

But it has been done and use PET scans and a variety of techniques that allowed, both in humans as well as in animal models, that allowed for all this wealth of knowledge to come together. Something I've been arguing is that in the past 40 years, we really learned a lot about this. And when you put it all together, it allows us to make some bridges between reality at the biological level and the inner reality of psychology,

the mental reality that everybody has inside the inner world that is revealed during dream. One of the things I think is really interesting about dreams is how they're both universal but incredibly personal at the same time. So following on from that, one argument that you also make in the book that I also found really interesting is that dreaming evolved as human culture evolved. Yes, this is super important because we have to first recognize the explosive nature of cultural accumulation in our lineage. you know, in biological terms, 300,000 years is quite little for evolution.

And this is the span of Homo sapiens in the world, as far as we know, with the fossil evidence that we have right now, a little bit above that. Of course, we can talk about the human experience, and then we're talking about different species of humans, and then we can go back to half a million years ago or even before. And the question is, how did we change so fast? So we changed so fast because we were able to share knowledge in a very different manner and produce new knowledge on a very fast scale.

And so when we look at cultural innovation in the past, say, 300,000 years, you see that this is like an exponential. It's just really accelerating more and more and more. And in the past few thousand years, this is very obvious. Now, what allowed that? What is that cause all that? Of course, language is involved. And one thing I've been contending is that dreaming is necessary for that. Because we cannot imagine new solutions, new things, new futures, when we are being chased by a predator or working very hard to do something that is tremendously needed.

We need to create and we actually are able to create when we relax, when we are either daydreaming or night. And one thing I've been proposing is that it was the dreaming with very emotional situations, and in particular, dreaming with the deceased, those in your family that have died and that you loved so much, this experience that is still very moving to any person in this current contemporary society, urban society that doesn't give a damn to dreams. But in the past, this was a very, very critical experience for knowledge to be shared and advanced. And why I say that? Because pretty much all terrestrial mammals

and perhaps all mammals dream. But we are the only ones that can share dreams and use language to share that. And those experiences in the early morning, people sharing their dreams and telling dreams with ancestors that taught new songs, new names, new strategies, new roots, something that is very well documented in ethnography

among contemporary hunter-gatherers. This was a very strong way to move culture forward. So yeah, this is maybe a little bit of a tangent from where we've been going, but I just thought you mentioned something interesting there, and a lot of people would want to know. So you said, all mammals dream. So do other animals dream?

And how do we know that? Well, so, of course, if it's not a human, we can only infer dreaming from the behavior and the physiology that we can observe. in the 60s, French neuroscientist Michel Jouvet showed that if you experimentally does inhibit neurons that block muscle movements during REM sleep in cats, cats will act out something that seems like a dream. They will pounce and they will attack and do many sorts of species-specific behaviors that really give us the impression they are dreaming. Of course, I don't need to say that to pet owners. But this is to say that this was addressed.

in the laboratory, you know, half a century ago. So we have good reason to believe that most mammals dream, perhaps not the aquatic mammals that don't seem to have REM sleep, but that's, I would say, we still need to know more about their sleep before we nail it down. But possibly birds as well, they also have REM sleep, and reptiles, when they are quite specific temperature ranges. And recently, in our own laboratory,

we've reported that something that we call active sleep, that is the behavioral equivalent of REM sleep, occurs in the octopus. So it is possible that many, many different animals, different types of animals dream. But of course, if we are to take the physiology and the behavior seriously, then those dreams, if they exist, must be quite short because all those groups except mammals,

active sleep lasts for very little, for dozens of seconds to up to a couple of minutes. In humans, though, we can go up to 40 minutes, 50 minutes of continuous REM sleep, and the platypus even more. So we need to think that as far as dreaming is a long experience, able to simulate sophisticated behavioral strategies and situations, it's a mammalian thing.

So, yeah, you just mentioned there, though, that we can go into REM sleep for periods of up to 50 minutes. But something that I wanted to ask from a sort of personal perspective is, I often find I'll go to sleep, I'll have a dream, which seems to last for hours, and I'll wake up, and I'll only have been asleep for 15 minutes. Do we know anything about that? Because that's something I find really fascinating.

This is a very old question that is still being debated on several, on several fronts. Certainly, we have the impression during dreaming that time can be compressed, but also slowed down. Those two experiences exist. The compression of time has been, people have proposed that it comes from the more editing of the scenes. Like, I was dreaming, I was in New York, and then suddenly it was Rio de Janeiro.

And this cut in space, it may be interpreted by the dreamer as a, as a temporal gap. So this is one thing. Another thing is that people have been proposing for decades that the way you move your eyes during dreaming is actually reflecting the scanning of the dream scene. And there's evidence in both directions. There's recent evidence in rodents that this may be true.

But there's also evidence in rodents that the neuronal processing that occurs during sleep, may be compressed. So I think it's still, this is at the frontier. And I think it's the more we know about the experience of dreaming, the more we learn about the psychology of dreaming, the bridges with physiology will become more clear. Another question you probably get asked quite a lot

is why do some people seem to be able to remember their dreams more than others? I remember my dreams nearly every night, whereas a lot of people I know say they rarely remember their dreams. Right. So of course, there's many different possibilities there. One is genetics. The other is life habits. Right. So if you, if you, do you sleep early? No, I sleep very late. Very late. Do you wake up late? Yeah. Okay. So that, that helps to remember dreams. It's really bad for remembering dreams if you wake up on a hurry with a beep. those are things that will make your last REM sleep episode shortened or perhaps absent. So this is one thing. The other thing has to do with, for example, substances.

If you have a lot of alcohol at night, that will curtail your REM sleep. If you have candidates at night, this will impair your ability to remember dreams, perhaps not having them, but remembering them or putting together the report on them. and other in sleep pills sleep pills are bad for for dream reports so there are many different things there a lot of exercise at night or too much food at night

all those things can have an impact on top of that there there's a lot of genetic differences between us and people have different propensities to to dream and to have specific kinds of dreams some people always have a certain kind of dreams some people never had that kind of dream some people have a propensity for lucid dreaming,

which is when people are conscious that they're dreaming and can control the dreams to some extent and something that can be learned and practiced. So there are many, many differences there, but one thing that we can say is that in contemporary urban societies, we are at sleep loss and dream loss. And one thing I've been proposing and defending and actually to some extent suffering about

is that we are in peril. We are, the situation we're facing in the world has a lot to do with sleep loss and dream loss. What is the situation? The situation is that of tremendous, tremendous accumulation of knowledge, tremendous accumulation of capital and tremendous accumulation of despair. Isn't it so paradoxical that we can, we have all this potential and we see no good future ahead. This seems like a physiological problem, an emotional problem, and it has to do with our abandonment of sleep as something sacred that we should protect at all costs. And why? Because

everybody needs to work and have fun. Two, the abandonment of remembering one's own dream. This is the situation you'll find with most people is that they are disconnected from their dreams. Third, and very importantly, even when people are able to remember the dreams and record them on dream diaries, they often fail to do something that was essential for our ancestors, and it's still essential for most people outside of the contemporary urban society, which is to share dreams. Dreams have been important in our lineage because they allow us to make individual desires and fears collective. If we don't have this kind of bond, where are we going? and people are feeling more and more lonely. And this is probably coming from a very sheer lack of sleep and dream. That's really interesting.

You make a lot of interesting points there. So what do we know about what influences the content of our dreams? We know a lot about that, and we know that this content is both meaningful and analyzable. You can figure out where things are coming from, and many of them are coming from waking experiences, what Freud called the day residue. you. There's also some chaos there that has to do with not only the deactivation of prefrontal

brain areas, but also with the lack of norapinephrine during REM sleep, which will make the dissemination of electrical activity during REM sleep more free than it is during waking. So there's more freedom when you're in REM sleep, and unlikely associations may pop out. And so you will have to, when you interpret your own dream, and the person that is really well qualified to interpret one's dream, is the dreamer himself or herself. Of course, it can be aided by professionals or by friends or family, but you're the only person that can really say,

well, this makes sense to me or not. And of course, a dream doesn't have to have a single meaning. It may have multiple polysemic meanings. But there's chaos there. There's some degree of noise there. And this is important for creativity. This is important to find solutions in when in a cornered situation. And when you are when you're not under very strong pressure of either fear or desire,

dreams tend to be very multiple. They tend to be a collection of images and symbols that make sense individually, but sometimes not as a whole. However, when you're facing. something that is very meaningful that involves a very strong desire or fear, dreams tend to coalesce. They tend to come as a whole. They tend to come as a very poignant story that you can carry for your whole life, in fact. And this is very well documented by anthropology, how this is still so, for so many different societies in the world. So sort of on the, as I was saying, I'm a very

vivid dreamer, which is great if I have a good dream. But also, I do something. sometimes suffer from nightmares, which are really unpleasant. So why do we get nightmares? What's their purpose? How do they come about? Nightmares are probably the grandmother of all dreams. One thing I've been proposing is a narrative, a plausible narrative, about how dreams evolved. And this is, of course, in the context of all the fields.

It has to do with a theory put forth by Ante Ravon-Souw. in Katia Valley in Finland, 22 years ago. And this is the threat simulation theory. So it proposes based on dream data from children in the world in different countries. It proposes that the most ancient purpose of dreams was to warn us against impending threats, was to simulate possible futures that were quite dangerous and allow us to change the course of action so as to avoid that danger. Of course, this is only explanation for, say, half of the dreams that have a high anxiety tonus, and this has been measured across the globe.

But, you know, we need to talk about the other side of the coin, which is pleasure, which is expectation of reward. So a lot of dreams have to do not specifically with having the rewards. The classical Freudian wishful-fulfilling dream is quite rare on most occasions, but the pursuit of rewards. So many, many dreams, in fact, a majority of dreams have a structure that has to do with goal-oriented behaviors, with reward-seeking. And for whatever reason, you may say, oh, I spent the whole dream going from here to there searching for a person. This is quite common or trying to find a certain object or to be in a certain place. And often we don't get there.

But sometimes we do. And this can be very meaningful when people are really committed to introspection, when they're committed to mapping their inner worlds, their unconscious, using dreams as a tool. So there's another aspect. One thing, another thing that struck out to me when I was reading the book was how you said dreams have like a kind of life-changing power. And the example that you gave was the person who had a dream

that they were in a doctor's office and they were shown a scan of their lungs and they had lung cancer. So that led them to stop smoking. I mean, is that a common thing? I think that's fascinating. Yes, and this came actually from Dr. Demand, a great researcher that discovered the link between Ramsey,

and dreaming back in the 50s. So this is very common, but it's not so common anymore in urban contemporary society, because we're cutting our connections with all this tradition. But if you look into the literature of the antiquity, the Middle Ages, across cultures and religions, and if you look into the experiences of Amerindian populations or Australian Aboriginal populations, you'll find this very strong connection and you'll find that people pursue and seek these grand dreams,

these major dreams, these big dreams, something that was described and studied by Carl Jung in the context of psychology. So most of us have this experience during childhood in adolescence, but this is something that is lost when we go into adulthood and we go into the demands of work and time and social schedule. And indeed, I don't see how we can go much further

if we continue on this path, because it's a path that disconnects us from the things that make us meaningful. What makes us meaningful is not that we acquire more stuff. What makes us meaningful is that we have meaningful experiences that are well connected with our past and in harmony with our past, to as much as we can make it happen.

And this is something that dream is really good at. Dreaming involves the activation of the brain areas that are not only necessary for storytelling, for imagination, for remembering stuff, but also for having empathy, for being able to imagine other people's minds and put ourselves in their shoes. This is super important for society to thrive.

If we don't have empathy for our knowledge, neighbors, for people that are not personally known, this is not going to go well. It's not going well. Let's look at what's happening in Ukraine. So we need to, in that sense, go back to ancestral, time-tested, quite healthy practices that involved treating sleep and dreaming as very important, not just for the individual, but for the collective. We were never allowed. We were never alone, the human lineage is a lineage of groups of people. And the current society is isolating people. And dreamtelling was the glue. Dreamtelling was bringing people together, making everybody aware of the individual's fears and desires. So when we are aware of the other people around

us and we know how they face challenges and what is difficult for them and how they can help you also. We create the glue. We create the social sense of purpose. And we're really lacking that. And we're going, I think, very fast in the direction that was, that we started nearly 500 years ago, which is to make money, God, to put money in the place of God and go in that direction so fast that now we have hundreds of millions of people starving in the world. And we have 10 people, the richest men in the world that just doubled their wealth during the pandemic. So what is this? What is going on?

And of course, if you go and talk to really rich people, you find that they're people too. They're suffering as well. And usually they're suffering for some money-related issue. Most of them are suffering because they wanted more, even more. And this is so prized in society. And the fact that we cannot really understand how crazy it is has to do with sleep loss and dream loss. obviously there's so much that's unknown about dreaming but as somebody who researches this what would be the number one thing that you would like to know that

we don't know oh well I think there's well I'm fascinated by lucid dreaming because when you are in lucid dreams you can sort of navigate your own unconscious and you can defy all sorts of laws of nature because you're in your inner world So this really allows you to go further deep inside so that you can access memories that were not accessible. It also allows you to imagine things that are really far-fetched. So I think it may work as a very good mental workspace for the next few millennia. If we are able to solve the riddle that is facing us so menacing that we need to, to figure it out. So basically we need to understand the competition was cool when food and everything

else were scarce, but now that there's abundance, we need to do differently. We need to adapt. And I think if we're able to eat well, exercise, sleep well, and dream well and share dreams, we'll just do it. It's going to be, people are going to look in the future and say, oh, those guys around the invention of the internet, they got it, they figure it out. And now everybody's happy here. We can really make it happen. And I think that lucid dreaming will be a tool for that. However, we will need to first rescue regular dreaming. Thank you for listening to this episode of Instant Genius.

That was neuroscientist Sidata Hibero. If you want to know more about the science of dreams, check out his book, The Oracle of the Night. The current issue of BBC Science Focus magazine is out now. Pick up a copy in store or visit sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analogue warmth.

Alongside French acoustic specialist focal, Name creates high-end audio systems, combining innovation with craftsmanship, so you can listen to music, just as the artist intended. Discover more at Name Audio. Thank you.com. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. Some follow the noise. Bloomberg follows the money, whether it's the funds fueling AI or crypto's trillion dollar swings. There's a money side to every story. Get the money side of the story.

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