Dr. Matt Walker: The Science of Dreams, Nightmares & Lucid Dreaming | Huberman Lab Guest Series

Welcome to the Huberman Lab guest series.

Where I and an expert guest discuss.

Science and science based tools for everyday life. I'm Andrew Huberman and I'm a professor of Neurobiology and Ophthalmology at Stanford School of Medicine. Today marks the sixth episode in our six episode series All About Sleep with expert guest Dr. Matthew Walker. Today's episode focuses on sleep and dreaming.

As well as lucid dreaming.

We talk about what's happening in your brain when you dream, both mundane dreams as well as heavily emotionally laden dreams. And we discuss how to think about and perhaps even interpret the content of your dreams. And we talk about lucid dreaming, which are dreams that occur while in sleep, of course, in which you are aware that you are dreaming. And because unfortunately they are relatively common, we also talk about nightmares and both what to do about nightmares as well as how to think about nightmares. This being the final episode in the six episode series All About Sleep, I put the call out on my social media handles for any and all questions about sleep that I could direct to Dr. Matthew Walker. So as today's episode closes, I ask him those questions, focusing specifically on the questions that were most frequently asked by you, the audience, and he answers them in rapid succession. Before we begin, I'd like to emphasize that this podcast is separate from my.

Teaching and research roles at Stanford.

It is however, part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is BetterHelp. BetterHelp offers professional therapy with a licensed therapist carried out online. I've been doing therapy for well over 30 years. Initially I had to do therapy against my will, but of course I continue to do it voluntarily over time because I really believe that doing regular therapy with a quality therapist and is one of the best things that we can do for our mental health. Indeed, for many people it's as beneficial as getting regular physical exercise. The great thing about BetterHelp is that it makes it very easy to find a therapist that's optimal for your needs. And I think it's fair to say that we can define a great therapist as somebody with whom you have excellent rapport, somebody with whom you can talk about a variety of different issues and who can provide you not just support but also insight. And with BetterHelp, they make it extremely convenient so that it's matched to your schedule and other aspects of your life. It's if you'd like to try BetterHelp, you can go to betterhelp.comhuberman to get 10% off your first month. Again, that's betterhelp.comhuberman Today's episode is also brought to us by Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means plenty of the electrolytes, magnesium, potassium, and sodium, and no sugar. As I mentioned before on this podcast, I'm a big fan of salt. Now, I want to be clear. People who already consume a lot of salt or who have high blood pressure or who happen to consume a lot of processed foods that typically contain salt salt need to control their salt intake. However, if you're somebody who eats pretty clean and you're somebody who exercises and you're drinking a lot of water, there's a decent chance that you could benefit from ingesting more electrolytes with your liquids. The reason for that is that all the cells in our body, including the nerve cells, the neurons, require the electrolytes in order to function properly. So we don't just want to be hydrated. We want to be hydrated with proper electrolyte levels. With Element, that's very easy to do. What I do is when I wake up in the morning, I consume about 16 to 32 ounces of water, and I'll dissolve a packet of Element in that water. I'll also the same when I exercise, especially if it's on a hot day and I'm sweating a lot. And sometimes I'll even have a third element packet dissolved in water if I'm exercising really hard or sweating a lot, or if I just notice that I'm not consuming enough salt with my food. If you'd like to try Element, you can go to drinkelement spelled lmnt.com huberman to claim a free Element sample pack with your Purchase. Again, that's DrinkElementlmnt.com Huberman Today's episode is also brought to us by Helix Sleep. Helix Sleep makes mattresses and pillows that are customized to your unique sleep needs. It's abundantly clear that sleep is the foundation of mental health, physical health, and performance. When we're getting enough quality sleep, everything in life goes so much better. And when we are not getting enough quality sleep, everything in life is that much more challenging. Now, one of the key things to getting a great night's sleep is to have the appropriate mattress. Everyone, however, has slightly different needs in terms of what would be the optimal mattress for them. Helix understands that people have unique sleep needs and they've designed a brief two minute quiz that asks you questions like.

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Dr. Walker, my dear good fellow Dr.

Huberman, today is the sixth and final episode in the six episode series that we've been recording on sleep. During episode one, you told us about.

The biology of sleep and some actionable.

Items to get the basics of sleep well worked out for each of us and it's highly particular to our individual needs and you explained how to define those needs. Then you beautifully described in depth protocols for let's call it optimizing one's sleep. And then a third episode focused on caffeine napping and also food intake and its impact on sleep. We talked about the relationship between sleep and learning and memory and creativity. And then of course, in the fifth episode just prior to this one, you beautifully described the literature and actionable tools for connecting sleep to emotional health and mental health, as well as the relationship between lack of sleep and certain mental health challenges or conditions. Today we are going to dive into a truly exciting and fascinating topic which is dreaming. I can think of fewer topics more intriguing than dreams. I know there's a lot of interest in lucid dreaming, that is one dreaming while being aware that one is dreaming. You'll tell us more about that. But I think dreams just intrigue and fascinate us for so many reasons, but.

Not the least of which is that.

At some point we all seem to have them and they seem to have a relevance for our lives. They're not just epiphenomena, as we say. So today I know you're going to explain what they do and do not provide for us. And I'm really excited to dive into this topic. It's something that I've been fascinated by and I know many people are fascinated by. So just to kick things off, how do we define dreaming? What is a dream? What is a dream state?

You would think it's fairly simple because when people say, I had the strangest dream last night, everyone seems to know what a dream. And by the way dreaming is, we take it for granted. We say, oh, I had a strange dream last night. Just think about it though. Last night, both you and I and everyone listening, as long as they slept, we all became flagrantly psychotic. Now, before you reject my diagnosis of your nightly psychosis, I'll give you five good reasons. First, when we start to dream, we see things which are not there, so we hallucinate. Second, we believe things that could not possibly be true, so we're delusional. Third, we get confused about time, place and person. So we're suffering from disorientation. Fourth, we have these wildly fluctuating emotions, something that psychiatrists call being affectively labile. And then how wonderful. You woke up this morning and you forgot most if not all of that dream experience. So you are suffering from amnesia. If you were to experience any one of those five symptoms while you're awake, we'd probably be seeking psychological or psychiatric treatment. But for reasons that we still don't fully understand, that seems to be a normal biological and psychological and in fact, and I'll describe the data, absolutely necessary life support perhaps, necessary set of experiences to go through. So that's the peculiarity of dreaming. But how do we define it? One of the loose definitions that we often use in sleep science is that a dream is any report of mental activity upon awakening. So I'll come into the laboratory and I'll wake you up and I'll say what was going through your mind? And if you just say nothing really, then we note that down as no dream report. But if you were to say, well, you know what I was actually just thinking about the next time you're going to come in and wake me up, then we would report that as a dream. But that's not really what most people mean when they say I had this strange dream. What they're referring to is dreaming that takes place during the stage of sleep called rapid eye movement sleep or REM sleep. And during REM sleep there we have these bizarre hallucinogenic, these vivid, these narrative, these emotion filled story experiences. Those are the types of reports that we get principally from REM sleep. So if I were to go back to episode one and say, think about those different stages of sleep, light non REM sleep, deep. Remember non REM sleep and REM sleep. When does dreaming occur? Well, if I wake you up during stage two, non REM sleep, that's one of the lighter forms of non rem. Early in the night, but especially later in the night, you typically will report a dream, maybe about 50% probability. 50% of the time I wake you up out of that stage. No. Report the other half. Yes. If I wake you up to a deep non REM sleep, stages three and four, we're down to a 0 to 20% chance that you'll report a dream. So very, very unlikely, if I wake you up out of REM sleep, somewhere between 80 to 90% probability that you were going to report a dream. There's nuance in that REM sleep story, by the way. Rapid eye movement sleep is defined by those rapid eye movements. But when you're in that stage of sleep, you're not always having the eye movements. They come in these strange phases. So you will be in REM sleep and we can define that with lots of different sensors on your brain and your body. But then there will be times when your eyes are darting back and forth and times when your eyes are not. And when those eyes are moving during REM sleep, we call that phasic REM sleep. And when they're not, we call it tonic REM sleep. Don't worry about the terminology. When I wake you up out of tonic REM sleep when the eyes aren't moving, I'm around that 80% probability. If I wake you up out of REM sleep when your eyes are darting back and forth, there is 95 to 100% probability that you're going to record a dream. Some people theories in the past have said, well, if that's the case, then presumably those eye movements are tracking something in the dream. If you do careful analyses, that just does not seem to hold up. There is some evidence that that may be the case. But your eyes are moving back and forth. It seems that these are impulses that are going to your eyes that don't have a strong correlation with what it is that you're dreaming visually in the scene. That's not the case, but that's a little bit of a definition of what dreaming is. And also when dreaming occurs. I should probably note, by the way, that we human beings, we seem to be special in our REM sleep dreaming amounts. Now, I'VE just done a little bit of a sleight of hand. When I say REM sleep, I'm going to infer that it's dreaming. But Charles Nunn, wonderful scientist, has looked at the proportion of REM sleep across different mammals. And what he found was that we human beings are a complete anomaly when it comes to our relative amounts of REM sleep, in other words, our dream sleep. He found that across most other primates, REM sleep was usually averaging about 9% of the sleep period. However, we human beings, on average, including when we're young, will have a REM sleep proportion of about 20%. So if you plot the amount of REM sleep of primates in a graph, they're all sort of clustered around this mean and then all of a sudden, on the far right hand side, you've got this one single data point that sticks out. That's us human beings, and we don't fully understand why it is that we have such exceptional amounts of REM sleep. Now, I've done a lot of hand waving and written some theories about why that is, but it's still very unclear. The other thing, and that's a very. I can go very philosophical about the functions of REM sleep and how it changed as we made the transition as a species from tree to ground. Because don't forget, as we mentioned in one of our episodes, when you're hanging like a bird on a tree or you're resting on a branch as a primate up in the trees and you go into REM sleep, you lose muscle tone. So it's quite a fragile state when you're 30 foot up in the air and you've got gravity desperately wanting to bring you and your, your limbs down to the ground. But when we made the transition down from tree to ground, we no longer had to worry about that. Did that open up the opportunity for more REM sleep to occur? And that explains why we human beings have that we don't know. REM sleep, however, does seem to be quite fundamental and fundamental from a life necessary perspective. There were some studies done back in the 1980s and there are studies that have not really been replicated. And I think I agree as to why, because ethically, they're right in that gray zone. In fact, for me, I find them quite uncomfortable when I speak about them or even teach them in class. They took rats and they deprived them of sleep totally. And what they found was that rats on average will die somewhere between about 13 to 17 days after total sleep deprivation. In other words, rats will die Almost as quickly from sleep deprivation as they will from food deprivation. It's that essential, brutal. But then they did something different. They said, well what about the different stages of sleep? So they selectively deprived them of either non REM sleep and REM sleep. The hypothesis was perhaps that non REM sleep is from an evolutionary perspective, a much older form of sleep. The first stage of sleep that came into being was non REM sleep. And the way we answer that is we look across phylogeny and these sort of different branches and what we find is that in insects and in reptiles, amphibians and fish, they all seem to have a non REM sleep. But for the most part, with a few exceptions, they don't seem to have REM sleep. But if you look at birds and mammals, they do have REM sleep. And in fact it seems as though REM sleep evolved twice independently, once in birds, once in mammals, which tells us probably that it's essential if it's been forced through the evolutionary pipe twice independently. So you would argue, well if I selectively deprived you of non remote, the older stage of sleep, presumably that's more life support necessary and REM sleep, REM sleep is the new kid on the block. Evolutionarily they found the opposite. They found that if they selectively deprive rats just of non REM sleep, they did die, but it took them longer. They died after about 60 days. If you deprive them of REM sleep, dream sleep, they died after 40 days vs 60 days vs in other words, this new type of sleep, REM sleep seems to be on that basis maybe even more important to supporting life than non REM sleep.

It's super interesting and as I recall from graduate school, there are certain patterns of brain activity that occur during rapid eye movement sleep. Maybe we could go a little bit deeper into those patterns of activity. I know you touched on some of these patterns in the first episode. The thing that comes to mind here is PGO waves, pons geniculate occipital pons being an area of the brain stem that is chock a block full of different neurons involved in basic functions. Rhythmic breathing, eye movements and basic reflexive functions that preserve the well being and life of the animal. And that the neurons there then do indeed connect to the thalamus. This is egg like shaped structure in the middle of the brain where you have something called the geniculate which is a, there's an auditory geniculate and a visual geniculate, but that projects to this relay station for vision mainly and hearing. And then it goes up to the occipital lobe, the area in the back of our brain that incited people is responsible for conscious perception of images. And I was taught, and I don't know if this is still true, that based on the work of people like Mercier, Steriot and folks like that, that these pons geniculate occipital waves of activity that were ongoing during sleep, I think during REM sleep were essential for resetting something essential about brain function and wakefulness. So that you needed these PGO waves and that maybe even the activation of the visual pathway was part of the reasons why we often experience such robust visual hallucinations during dreams. What is thought about PGO waves? Are they related to rapid eye movement sleep? And are they somehow the reset of that we need and indeed is essential for life? Because, as you pointed out, in the absence of rapid eye movement sleep, we die.

It's a great demonstration of the uniqueness of your brain. Essentially, what we're asking is, this is your brain on dreams? Explain. And REM sleep has many different brain features to it, the first of which is, as we spoke in the first episode, your electrical brainwave activity at the top of the brain, the cortex, looks almost identical to that which you have when you're awake, which is stunning because you're not conscious. You're lying completely still, no presence of muscle tone whatsoever. Yet your brain seems to be just as on fire with electrical activity as it is when you're awake. Coming down a step, though, there are these unique pulses of electrical, almost like lightning bursts that come up from the brain stem up to this sensory relay center in your brain called the thalamus. And then they were initially recorded out in the back of the brain in the visual cortex. Hence, this PGO waves describes the three sites that I've just mentioned, goes from the brainstem to the pons up to the thalamus, a part of it called the geniculate, and then out to the back of the brain called the occipital cortex, pgo. What they found was that those bursts of PGO wave activity were very much linked to these rapid eye movements. So once you got this burst of a PGO wave, this sort of brainstem, up into the brain burst, then you got one of these rapid eye movements. So it was linking something there with the eye movements. And I told you that when you're having these eye movements, that's a state where there's a high probability of dreaming. And is it a surprise, then, that the final destination of that lightning bolt, where it sort of strikes is at the back of the brain in the visual cortex? Probably not. There's also been some links with those PGO waves and learning. Not so much that those PGO waves seem to consolidate memories. In other words, they may not be critical for sleep after learning, but they seem to be related almost to sleep and initial learning. And the more that animals learn, the greater the amount of PGO wave activity they have when they go to sleep. So PGO waves are unique. PGO waves don't simply just hit the back of your brain. That we've now measured them in all sorts of different cortical areas and, and they seem to light up. The lightning splits, as it were, and it strikes all sorts of cortical areas. So then the question was, well, let's take humans and let's put them inside of brain scanners, let's allow them to fall into REM sleep and then we'll start scanning the brain. What did we find? It was very interesting. When you look at the brain during REM sleep, compared to, let's say, non REM sleep, you see motor regions of the brain lighting up. You see visual regions of the brain lighting up just as we described. You see memory related structures lighting up like the hippocampus, and you see emotional related structures like the amygdala and something called the anterior cortex, the anterior cingulate cortex, I should say. So if I were to just show you an expert, a brain imaging map with memory centers related in terms of their activity, emotion centers, visual centers, motoric centers, and I were to say to you, Andrew, this is a scan that we got from an individual. Just describe the type of experience that you think this person was having in the scanner. You would probably look at it and say, well, they were probably recollecting things from their past memory structures. They seem to be having a visual experience. But there was also probably movement involved in that brain scanning experiment. And also there seems to be some degree of emotionality to it that sounds strikingly similar to what we know dreams are like. With one exception, though, another part of the brain bucked the trend of increased activation during REM sleep. That part of the brain was with the far left and right sides of your frontal lobe, something that we call the dorsolateral prefrontal cortex. Terrible mouthful, word salad essentially just means the far left and right sides of your prefrontal cortex. Those are very important for logical, rational thinking and decision making. Those parts of the brain went down in their activity almost as though they were suppressed during REM sleep, dreaming. So now, let's go back to our map. You're having a visual experience. It's filled with movement and memories and emotions, but it's utterly bizarre, completely illogical and totally irrational. If that's not a perfect neural definition of this thing called dreaming, I don't know what is.

It's so interesting. We think of dreams, or at least I think of dreams as a fragmented representation of real world experiences from our recent past, maybe even the previous day, sort of meshed with our distant past experience. And then, of course, our brain is also a very good anticipatory machine and somehow puts that into a movie that for all purposes, when we're in it, we feel as if it's happening in real time. And then, of course, we try and untangle what the meaning of all that is. I think people are really intrigued by dreams because they just feel so real to us and yet we know they're not of the same real, that is our waking experience. And throughout history, people have alluded to the idea or have been convinced of the idea that that dreams are meaningful and something we're going to get into.

And I should mention, by the way, that your dreams based on those brain scans still remained your own. You were the only person privy to the experience of the dream itself. I could stick you in a scanner and I could say, you know, were you having a visual dream and was it, you know, filled with motor activity and emotions and memories? That tells me how you're dreaming, it doesn't tell me what you're dreaming. So at that point, you still had this degree of security and privacy. No longer, it seems. There was a great study done by a Japanese group using very advanced brain imaging technology and techniques such as multivoxel pattern analysis. Again, word salad, but it's a very clever technique. And they were able to start to understand exactly what you, Andrew Huberman, were dreaming. And they would know what you were dreaming even before you woke up and told us what you were dreaming. And they did a two part experiment. First they showed you lots of very specific images. Images of cars, of women, of houses, of men, of dogs, of cats, of just a whole category of different visual elements. And your brain was being scanned as you're awake watching each of these. And then using this clever analysis, they were able to build up this very specific pattern, this very specific template of activity that for you, Andrew Huberman, said he is now looking specifically at a set of keys, or he was looking at a car, or he was looking at a woman or a man or a house. And we knew ground truth in terms of what your brain looks like when it is seeing these different categories. And then they did something clever. Then they let those individuals sleep and go into REM sleep and then they started waking them up and getting dream reports. But once they got the dream reports, the analysis sort of team remained blind to those reports. What they did was almost like a forensic team that goes hunting for DNA at a crime scene. They had the DNA and they started going around and searching to see if they could find a DNA match. But here they weren't using the DNA, they were using these templates of a woman's face or a car or a house. And they would search through this electrical or this brain activity, sort of static of your dreams at night and find these matches. And then we could wake you up, get the dream report and see how well did our brain performing a sort of algorithm match with your actual subjective report when you came out. And it was stunning how close. So I could tell you were dreaming, but you were also dreaming about a house and a car. You're dreaming about a woman. Turns out, and we started to once your dreams, as I said, were your own, but now no longer, because science can start to reveal those. What we can't yet do is understand which specific woman in which specific house. So what you would probably see my brain, based on my own proclivities lighting up, is it would just be full of cars, probably sports cars, and then maybe another special individual woman. Those two things would be dominant. But you wouldn't know that I'm dreaming about the new Porsche 911 GT2 RS. You can't tell that. You can just simply tell me he was dreaming about a car. So there is still some distance to go.

I can't help but ask, based on what you just described, when people say things in their dreams, when they sleep talk, how faithfully does that report what's in the dream?

It doesn't at all. And the reason is because when you're sleep talking or sleep walking or even sleep eating, you're not dreaming because you're not in dream sleep. This is one of the fallacies that sleepwalking or sleep talking, stop dreaming, wake up, you're dreaming, you're waking someone out of the very depths of deep non REM sleep. And these different things, sleep walking, sleep talking, sleep eating, sleep, there's sleep associated sex behavior. All of these things are what we call parasomnias. Para meaning sort of around somnia, obviously sleep. So these are things that happen around sleep, but they're not quite in in sleep because when you have those you are launched from deep non rem sleep up to wakefulness. But you don't make it all the way to wakefulness. And so you act out these very rote routine reflexive behaviors. You just repeat certain words, you lift a cup to your mouth, go over to the refrigerator so they are not faithful to the dream. Because if I were to gently wake you as you're sleep talking and say what was going through your head, you'll say nothing at all and you don't report a dream.

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You described beautiful experiments by Matt Wilson. Others at M explored neural activity within the brain, within the hippocampus, in particular an area associated with memory formation in which the neurons in the hippocampus fire in the same sequence as they did during a particular daytime activity that preceded that night's sleep, but they do so at a much more rapid rate. Sometimes they play in reverse, et cetera. This raises the question of first of all, is that sort of neural replay of events from the prior day? Is that also associated with dreaming or more specifically, is that dreaming or is dreaming that? And that's really to raise the larger question, which is what is dreaming for? What is the function of dreaming?

So what we know is that Matt Wilson's data, during non rapid eye movement sleep, the brain was replaying those memories 10 to 20 times faster. But when you go into REM sleep, it's down to 0.5 times. So listening to this podcast now and you hit that speed button and you drop it down to 0.5, that seems to be the replay speed during REM sleep. We've not yet been able to confirm that in human beings, but if we did, does that mean we can explain the time differences that seem to happen in the dream state? That time is longer in the dream world than it is in the waking world? I think that's fascinating. But you're right, it does point us more towards the question though of what are the functions of this state called dreaming. And we can get onto whether or not dreaming is a very faithful recapitulation of our waking experiences. And I'll give you a spoiler now no, but I'll give you the data in a second. But the functions of dreaming come back to some of the functions of REM sleep that we described in an earlier episode. Those two related functions in the episode on learning in memory was that one function of REM sleep seems to be creativity, associating memories together so that you can come up with these wonderfully divine solutions to problems you couldn't answer when you were awake. The second came in our last episode about emotional and mental wellness. And we spoke about this theory that we put forward that REM sleep is a form of overnight therapy. And we described the evidence supporting that therapy. So I would say that those are the two leading theories of REM sleep and associated dreaming. But I perhaps didn't give you the full story there. There is a twist in both of those stories. I told you that when you are in REM sleep and you're dreaming the next day, you are better able to assimilate and associate memories and come up with these creative insight solutions. It turns out that sleep is necessary for that and not just sleep, but dream related sleep. REM sleep is necessary for for that, but it's not sufficient. You not only have to be asleep and dreaming to get those benefits, you also have to be dreaming of the very things that you are trying to solve the next day. There's a great study by a scientist called Robert Stickgold at Harvard and he had a whole group of Individuals learn a virtual maze and they were dropped down in different locations of the maze, and they had to try to get out of the maze. And gradually, when you're dropped down in different locations, you do that enough times, you start to build up this mental map of the maze. And then he let one half of those participants take a 90 minute nap and the other half remained awake. And then some hours later, they tested them on the maze and they measured how quickly were you able to navigate and get out of the maze. That was the outcome measure. And sure enough, just as we described those people who slept versus those who didn't, they were better able to navigate the maze after they had slept versus those who remained awake. But then they went back and they separated those individuals who were napping into two classes, because as they were napping, they were waking them up intermittently and getting dream reports from them. And what they found was that those people who slept and still had dream reports, but those dreams were not related to the maze. They didn't show an improvement. But those individuals who slept and who dreamt but also dreamt of the specific maze elements themselves, they were the only subset of people, of participants who showed the benefit. And that's a beautiful demonstration that, yes, you need to sleep to get creative benefits and in fact, seemingly have dream sleep, but you also need to be dreaming about specific things. Is that rule true for the second function of REM sleep dreaming, this overnight therapy benefit? Yes, it does seem to be true. There were some great studies by a scientist who has sadly passed away now, Rosalind Cartwright, and she was looking at different patient populations who had undergone really painful, deep, difficult emotional experiences, for example, a very bitter, painful divorce. And she would, at the time that those individuals were going through this difficult challenge, she would be recording their sleep, looking at their different stages of sleep, and she was collecting dream reports from them. And then she would track them and their progression clinically over the next year. And what she found was that some of Those participants, about 50% of them, ended up getting clinical remission from their depression that was instigated by the painful experience they'd gone through. The other half did not get clinical remission from their depression. They remained depressed. And then she used those two classes to go back and have a look at the sleep and the dream reports. And what she found was some differences in REM sleep, but more interestingly were the differences in their dreams. Both of those sets of individuals were dreaming at the time of going through those difficult emotional experiences. Some of them, however, were dreaming of that challenging experience. Others were not. Those who dreamt, but also dreamt of the problematic experience were the ones who went on to get clinical resolution from their depression. Those who dreamt but did not dream of those events seem to be the ones who did not get clinical remission from their depression. In other words, here once again, is this new rule that when it comes to dreaming, it's not just about sleep and it's not just about dreaming. It's about dreaming of the specific things that you're trying to get the functional benefit from, whether that's creativity and insight or whether it's emotional resolution and overnight therapy. Both of them seem to depend very much on the expression of dreaming of specific things itself. And we'll come on to why that's maybe relevant when we speak about lucidity too.

What you just said is very reassuring, at least to me, because when I'm going through a challenging phase, which somehow seems to happen periodically in my life at a frequency that, let's just say, keeps me dreaming about things.

You're not alone, by the way.

No, I'm sure I'm not.

Which is. No, no, I didn't mean that. I just mean that there are lots of people who can resonate with that. So thank you for being vulnerable and sharing.

Yeah, yeah. It's one of these things where I put my head down on the pillow, fall asleep, and assuming I can get good sleep amidst those real life events, which is something that sometimes is the case, sometimes it's not. I always dream about things related to those events or those events in particular. And I'm a longtime practitioner of writing down my dreams when I wake up from them. Or as we discussed in an earlier episode, my phone is on airplane mode at night, typically I'll grab my phone and I'll hit the voice memo button or function rather, and I'll just in my groggy state with my eyes closed, so I'm not getting any light in my eyes. I'll say, I'll describe what I can recall of the dream. Then I'll sometimes go back and listen to those, those recordings and they've provided me insight and in some cases a path to solutions. So I'm 100% on board the fact that our dreams can help us resolve challenges in our waking day. What's always fascinating to me though, is how the dreams are not a one for one representation of what happened during the day. It's, you know, I think symbolism is a, is a, is a hallmark feature of dreams, you know, and that's something I know we're going to talk about in terms of dream interpretation and much has been made of this throughout history. So it seems that when we're asking what are the functions of dreaming, one of them is to resolve challenges from our daytime experience.

It's emotional first aid.

Yeah, that's beautifully put. And in an earlier episode on learning memory and creativity, you accept described how specific sleep stages, and perhaps dreams themselves, are involved in the consolidation of memories from daytime experiences or things that we're trying to learn from daytime experiences. And then in the episode on sleep and emotions, it was made very clear that rapid eye movement sleep is the time in which we get a sort of therapy that is a disentangling of the emotional load of a given experience from the experience. So to me, it just seems so clear, like, dreams are critical, sleep is critical. But I think one question that still remains unresolved, at least for me, is are dreams really there to just be a replay of our waking lives with some distortion? Because when the conscious mind is asleep, the unconscious mind can kind of throw things up to the surface in ways that don't seem so obvious. Symbolism, analogy. Some of us are more visual than others. You know, are there any rules about the way that dreams convert our waking experiences into dream content?

There are. And the short answer to your question, do we simply go into sleep, start dreaming, and then rewind the videotape and replay in a faithful recapitulation the waking day in our dreaming night? And the answer is no. And here again, the scientists I mentioned before, Robert Stickgold with Raw Fossey, they looked at this question and it was a very difficult study to do. They did what we call experience sampling during the day, and they would give you sort of like a little beeper and they would set it to go off multiple times throughout the day. And then you would write down what it is that you were experiencing right in that moment. And again, they were trying to build up this sort of time lapse photography, as it were, of your waking day experience. And then they would bring people in and they would start to record their dreams at night. And then they would match those two and ask, what is the degree of overlap? What is the Venn diagram, proportional percentage of those two things aligning. And, and what they found was that there was really only about 2% of your dreaming life that was a very faithful replay and reiteration of your waking life. However, what they did find was something even more interesting to me, which comes back to this idea of overnight therapy. They found that there is Something that runs through like a red thread narrative from your waking life into your dreaming life, that is emotional concerns and people of significance. If there is anything in terms of an algorithm that seems to overlap and predict where those two Venn diagrams sort of collide, it really is in the emotional personal significance space, once again, pointing us to perhaps a reaffirmation of that. A key function of dreaming is about dealing with our waking experiences and particularly the things that are salient to us.

Okay, so clearly there's a functionality to dreaming, but what should we make of the specific content of our dreams, really? Meaning, should we interpret our dreams or should we allow anyone else to interpret our dreams? There scores of books out there, websites, programs. There's a long history of this in classic psychoanalysis. What about this dream interpretation business?

I mean, it really started, you have to give credit in some ways to Freud. Although if you look back at very ancient cultures, so much of their artwork, so much of the sort of left imprint on the world, suggests that they were fascinated by dreams and used dreams and gods of dreams. So we've always been thinking about, what are these things called dreams and can we interpret them? But it was really Freud who put his seminal works together in 1899 and then published it in 1901 called the Interpretation of Dreams. And it's probably one of his, if not his most famous text. And you can unfairly sum it up as, you know, if it's not one thing, it's your mother when it comes to Freud. But in some ways, Freud, with his interpretation attempt in my mind, was 50% right and 100% wrong. Because until the moment that Freud came along, we left the interpretation and the instigation of our dreams to things outside of us. Maybe it was there were comments that it was due to our soul or it was from the gods on high that they would descend down these, these dream manifestos to us. But Freud, full credit, was the first person to put dreams front and center into this thing called the brain, the mind. So in some ways, Freud shifted dream science from really more of a sort of spiritual, philosophical condition to very much a neuroscience. It was of the mind and therefore of the brain. And earlier he had tried to describe the neural patterns, and he had these beautiful drawings of neuronal circuits that could try to explain what was going on. But neuroscience was so anemic at the time in terms of its knowledge, he had no chance to do what we can do now. So in some ways it's very unfair of me to criticize him as his theory Being non scientific, it is also non scientific in the very strict sense of the word. When we create a scientific theory, just as though he created his interpretation of dreams theory, we allow that theory to be testable, which is to say that a scientific theory is only a scientific theory if it can be falsified or supported. But Freud's theory was not a scientific theory. It was not something that you could test, and therefore it was not able to be falsified or affirmed. And in some ways it was Freud's simultaneous downfall and his utter genius. It's the reason that Freud remains to this day, because we can't put him in a way in a box and say we've disproven him, but we equally will never be able to prove him. And therefore he's been in some ways let go in hard science as being representative. His theory, which we don't need to get into, which was called disguised censorship, was really a very interesting proposition, which was that there was something about our dreams that was veiled and masked. And Freud believed that he understood the decryption code to our dreams. And if you tell him your dream, he has the special filter that he can pull that dream through the filter and magically out on the other side and is the true meaning of that dream. There are several problems with that theory, not least of which I think, you know, at the time, if you look at his writings, it seemed that Freud was probably doing enough cocaine to kill a small horse at the time. But we'll put that aside for a second. The issue there is that it's not very replicable as an analysis method. And there's a fascinating study that was, I remember from a conference, I should check to see if it's been fully published. And they did something clever. They took the Freudian method and they took a single dream from one individual and they had three Freudian psychoanalysts analyze that dream. So it was the same dream, but three different analysts. Now, in a scientific protocol, if it's a scientifically rigorous assessment tool, you would get back the very same answer from that measurement technique all three times or very similar. So, for example, a carbon dating machine, if I were to take a fossil and put it in a carbon dating machine, and then another, another one and another one, for the most part, they're probably going to return something that's much more similar than different in terms of the carbon date of that fossil. Why? Because it's been very well validated and replicated. That's what you want from a scientific method and tool but when they gave this single dream, the fossil, as it were, to these three different interpreters, the three different carbon dating machines, as it were, they all came up with completely different interpretations. And so that's not necessarily a reliable, valid method. So in that sense, we've abandoned and let go of Freud as being relevant or meaningful. However, I personally, and I think if you look at the data, I don't mean that to suggest that you should not try to think about and quote, unquote, interpret your dreams. And the term interpret when it comes to dreams is so loaded. So I tend to, I would just simply say, see if you can really deconstruct some of your dreams. I think dreaming, just as we've spoken about, is a very solid window into the things that you should be concerned about from your waking life. It's very obvious that whatever it is that we typically dream are the things that our brain is telling us, the human being. This is the stuff that's essential. This is the stuff you need to work through. This is. Please pay attention to me and any amount of journaling or deliberation, digestion, cogitation of that specific dream is going to be beneficial to you. Because in my mind, a life unexamined is not a life well lived. And that isn't just applicable to your waking life, it's especially applicable to your dreaming life. Now, does that mean I'm suggesting that everyone should race out and start cataloging and interpreting their dreams? Not necessarily, but I am saying that if you wish to do that, I, as a scientist, based on the data, I'm not telling you that that's hooey and non scientific. I think it's very valid. It's just that some of the Freudian principles I think we've been able to dislocate ourselves from.

I wholeheartedly agree with what you just said, and I've spoken about dreams and their possible relevance to clinician psychiatrists such as Paul Conti and others, some who have more of a psychoanalytic training than others. But certainly folks like Paul know a ton of neuroscience. They understand pharmacology, they understand family systems models, dialectical therapy, and so many other.

He's extraordinary. He's not extraordinary. He's extraordinary.

He is extraordinary, and in part because he can synthesize across all these different domains of psychiatry, psychology, neuroscience, et cetera, as opposed to just existing in one silo like psychoanalysis or psychopharmacology. And there are others, although few as extraordinary as Paul, which is why we hosted him on the series here. And One of the things that has come up in the discussions with Paul and others with similar training about dreams is that dreams seem to present us with emotional states and scenarios for which there's a lot of swapping in and out of identity. So, for instance, the notion of symbols within dreams is a long standing conversation. And I think one of the mistakes, as I understand it, is to assume that every time there's an animal in your dream, that it represents children, or that every time it's a particular kind of animal, it represents, you know, your boss or something.

Sometimes a cigar is just a cigar, right? Right.

On the other hand, it's very clear that within our dreams there's rarely a completely linear one for one relationship with what happened in the daytime of real experience. So there seems to be a swapping in and out. And there I just sort of zoom out. And forgive me for going long here, but I think this would be a good fodder for exploring this a bit more deeply. One of the best descriptions of brain function that I've ever heard is from the Nobel Prize winning neuroscientist Richard Axel at Columbia, who often talks about the brain creating abstractions of the outside world. So if I were to take a photo of your face, for instance, and then show you that photograph, you'd say, yeah, that's me. But if I were a painter, I might swap some of the positions of components of your face and show it to you and you might say, well, that doesn't look like me. And I'd say, but that's my abstraction of your face. So to me it makes sense because I understand the rules by which I made those swaps and moves. There's some algorithms or rules that are known to me. So there's a sort of preservation of real world to the abstraction. And that's really what our brain does all the time. It attempts to faithfully represent the world around us, but it is indeed an abstraction. And when it comes to the colors of things or the position of objects, it's as one for one, as our brain is capable of. But when it comes to ideas, to feelings, to our relationships to other people, the brain abstracts those in its own little neural symphony of this is the relationship to my dog, this is the relationship to my friend and colleague Matt Walker. So it makes sense that in dreams those algorithms could be different. They could be faster or slower, but they could also be entirely different. I don't think we yet know what the algorithms of transformation of real world experience to dream experience are. And once we do and I think someday we will understand those through electrical recordings and MRI type experiments. And some of the experiments you talked about earlier point to this. And so I think it's entirely reasonable to assume that we each have our own unique abstraction algorithms so that indeed we can have consistent representation of real world experiences in symbols, but that it's not going to be the same for everybody.

Correct?

Right. Your way of abstracting your real life to your dream life could be entirely unique to you and mine could be entirely unique to me, making it very difficult for a third party to come in and say, okay, Matt, here's what your dream means. But you can know what your dream means if you explore your dreams over time, not just that one dream. Does that make sense?

It makes total sense. Because in some ways there is no one who knows your own autobiography by definition, than you, than yourself. Now, I'm not suggesting that having that interpretation guided by someone who also understands the emotional problems that you're having and also sees your blind spots, which is what a really good therapist could do, can then help with that interpretation. But you're right, because my representation of information in the brain is going to be very biased by also what I've experienced in the past and how that past experience augments and modulates the current representation of that information and thus the meaning of it for me, the unique individual. And you're also right to say that it's somehow, you know, it's almost as though you're squinting your eyes when you're in dream sleep. In terms of the true vision of things, things get a little bit wacky and distorted, this bizarre nature. There is some very interesting data, and it comes back to what we described earlier, the neurochemistry of the REM sleep state. I told you that during REM sleep and levels of noradrenaline are at floor levels, noradrenaline is shut off. One of the things, if you sort of drop noradrenaline onto neural circuits, it will very much increase what we call the signal to noise. And this is why noradrenaline, when it's released or if you administer it to an animal, you can become very. You can become almost more directed. You're much more divergent. You're focused in attending, and it's really there. You're very blinkered, you're very focused. But when that goes away, the neural circuits become a little bit more loosey goosey. And I also told you that the other chemical, if there is a neurochemical that defines REM sleep dreaming, it's this thing called acetylcholine. And acetylcholine seems to do the opposite. It seems to inject a little bit more noise relative to the signal. So in other words, your brain circuits are neurochemically modulated when you dream to inject almost what we would think of as fuzzy logic. And this is why I think the analogy that we spoke about in a previous episode holds that when you are awake and you're given some information, you produce the most obvious links and obvious associations because you're very much blinkered and you have noradrenaline on board. But when you go into dream sleep, the it's almost like the Google search. When you're awake, go straight to page one and it's very related. But do that same search when you're in the dream state and it, you know, you go straight to page, you know, 35 and it's an utterly bizarre page. And you think, hang on a second, this has got nothing to do with the search term. But when you read it, you think, well, if I squint, my eyes kind of does. It's very distant, very non obvious. But that's a very smart connection that as a waking brain I never would have put together. So I think neurochemically we can start to understand it. But I think this is a very good important point where you could almost say the very best person to interpret your dreams is probably you.

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That's join.whoop.com Huberman Some dreams we'd rather not have here. I'm specifically referring to nightmares. I've had one nightmare countless times throughout my life. I won't share what it is. It's not a real world experience, or at least it's not a one for one of real world experience. But I've had this nightmare since I was a kid. I have it seldom these days. But every time it starts again, I'm like, oh no. And there's a bit of lucidity to it where I'm like, I hear him again. Been working on this one a while, as you can imagine. But given what we understand about the relationship between real world experiences and dreams, what should we make of the fact that we have nightmares? So let's just start there. The phenomenon of nightmares, does it represent something that troubled us in the daytime and that we're trying to work out in our sleep? And then maybe we can get into some of the specifics around why, regardless of whether or not the answer to that question is yes or no, that we would have this thing called nightmares. Especially given that there's all this machinery to make sure that we don't move and the noradrenaline is low in the brain while we're dreaming. Seems like there's all sorts of mechanisms to try and ensure that our dreams are very pleasant or at least neutral. But nightmares suck. But. So I'd love to know.

Give me that T shirt, please.

So I'd love to know that they serve some utility.

So nightmares. How do we define a nightmare in sort of science? Clinically, it's a little bit tricky, but usually the way we define it is it's a strongly unpleasant dream that causes some time of daytime displeasure. So in other words, some type of daytime dysfunction or distress. So everyone can have a bad dream, but when you go up into your waking life and about your waking day, it doesn't seem to bother you too much. And maybe we'll just say that's a bad dream. When it really becomes a nightmare is when I almost think of it as though you wake up and that blanket of strong nightmare emotion is still wrapped around you and you can feel it. You can just know there's my emotional state is still heavy and I know exactly where it came from and it was from that nightmare. And throughout the day, you don't seem to be able to derobe yourself from that cloaked affect of the nightmare drenches you almost. That's where it really starts to become unpleasant. And we actually do have a clinical category, it's called nightmare disorder. And the way we typically define that is the same thing, as I said, a very unpleasant dream that causes some type of daytime distress, and it's happening at least once a week. At that point, we start to move it into this category of nightmare disorder. What are nightmares doing, if anything at all? There are at least two theories. One is that it's simply the system failing, the system gone wrong, and we're not processing. We're not moving through things. And therefore nightmares are maladaptive. They're not warranted, they're not normative. The other is that, no, they are adaptive and they are meaningful. And it's us really trying to go to a very specific pain point. And we continue to process it over and over, perhaps to the point where we get resolution, but sometimes we just don't. So it keeps cropping up. We don't have good data to disambiguate those two right now. So I think it still remains open, at least I don't know of any data that tells me, are they functional or are they maladaptive? Even when we get that answer, in some ways, it doesn't change the fact that it still leaves a patient with nightmares, with recurring nightmares. So then what do you do about that? How do we. Is there any treatment for people out there if they're under this distress? Is there hope? And for a long time, there really wasn't very much hope at all. You just had to go through it. But recently there was a method that was developed, and it's very effective. And it is called irt, which stands for Image Rehearsal Therapy. And its basis comes back to something that, in fact, we, I think, hopefully published the first evidence in humans of some years ago now called memory reconsolidation. So in our episode on learning and memory, we said that there is at least sort of two main steps of memory. First, you have to imprint and learn the memory, lay down that memory trace. But then that memory is very fragile and vulnerable to being overwritten by competing information, knocked out of place. And for you to hold onto that memory, you have to go through a second step called memory consolidation. A very slow process. It's like a very slow pressing of the save button because it's biological. It requires protein synthesis and all of that good stuff. But that always struck me as a strange model because it's the equivalent of opening up a Word document. You type out all of the information into it and then you hit the save button. So I've encoded, imprinted the information, then I've hit save and saved it. And then I close that file. And then the next day I come back or some days later, and I double click on that file again because I want to edit it. I either want to add to it or I want to revise it and change it. But according to that model, it's been locked in place and you could never edit that Word document. That seems like a profoundly useless way to store information. And what we learned is that every time in subsequent days, when you reactivate, which is to say, when you recollect the memory that has been consolidated, it opens that memory file back up to once again being plastic and malleable. So you can go in and update the information in that memory store, and then the next night you consolidate it again. In other words, you reconsolidate it. So it's memory updating. And there is a very clear mechanism in the human brain that allows us to do this memory updating in iteratively, time and time again. This comes back to nightmare disorders. This therapy, image rehearsal therapy, or irt, will have you sit down with a therapist and at first you will describe the nightmare that you're going through and you'll write that narrative down. And then working with a therapist, you will agree to think about a more neutral ending to that nightmare. So let's say that I was involved in a very, very difficult car crash. It was just horrific. And every night since, I'd say at least once a week, I just continue to have the nightmare of the car crash. I know that I'm traveling towards the junction. I apply the brakes. The brakes have failed. I am just looking around, I'm trying to maneuver, but I. Nothing is going to change this. I go through the red light and someone sideswipes me and that's the end. And I relive that time and time again, and it's awful. So you with the therapist, or I with the therapist, would then start to say, well, what about the alternative scenario? I depress the brake and the brakes don't work. But gradually I think, well, I'm just going to reach over to the handbrake and I'm going to gradually apply the handbrake and. And that slowly is going to bring the car to a nice safe stop. And then I'm going to call the emergency services. The car is going to get towed. I don't go through the junction, I survive, everything's fine. So you rehearse this alternate ending and you keep going through that, rehearsing that, and then you go to sleep the next night and you'll probably have a high chance of that nightmare again. But if you keep going, doing that, once you've got that alternative ending, essentially what you're trying to do is every time you reactivate the memory of the trauma, car crash, and then you rehearse this alternate ending, it's like me going into the Word document and editing the section that was really horrific and bad and replacing it with something that's neutral or even positive. And over time, then I sleep and I will consolidate that memory. I'll come back the next day and I'll do some more editing and more updating. And time after time after time, gradually you dissipate the narrative that is fixed inside of the brain and the nightmare frequency decreases in proportion. Now, it's not effective for 100% of patients. If you look at the data, on average it's about two out of every three people. So about 66% of people will benefit. Which if you look at some medical treatments, that's a great treatment, that's still very effective. There was a very recent study from Sophie Schwartz and her colleagues at the University of Geneva that did an even more ingenious study and they were able to nudge the effectiveness of that treatment from 66% up to 92%. And they used an additional memory related research tool we've come up with in sleep science. And it's called TMR or Targeted Memory Reactivation. And here's how it goes. I'm going to have you learn a set of associations. Have you ever played that card game? I think in America it's called memory, which is very apt, where you get a deck of cards and and it has two of the same item. Two houses, two cars, two fire engines, two kettles. And you shuffle the cards and then you put them face down in a big square and a big matrix. And over time you have to turn over one card and it's a kettle. And then I'm just going to randomly pick another card and it's a fire engine. Okay. But gradually you start to learn where each one of the purrs are located. So what's clever about that is we would do that type of what's called a pert association memory test. You learn these pert associates and then we test you after a night of sleep and you're better. However, if for as you're Turning those items over, I play a congruent sound. So let's say you turn over the fire engine and then when you turn over the other fire engine, I'm going to start playing a fire engine noise in the background. So I'm bonding the association of the memory card purrs with this tone, with this congruent sound. And then a kettle, I turn over a kettle, I turn over the other kettle and it's whistling. And then when you let people sleep at night, if you start replaying those same tones at a subawakening threshold so you're not waking people up and you bring them back, and let's say that you only do those sound cue reactivations for half of the memories that you've done and the other half you leave untouched. So within an individual, you have a unique within individual control. You test them on the things that you didn't reactivate at night and those that you did. It's almost like creating a bespoke playlist at night where you say, look, I learned all of this information during the day, or wouldn't this be wonderful? And then here is the stuff that I really think personally to me, I want to remember. Well, it turns out I'd been tagging that with particular music and then at night I replay that music and the next day it turns out that those things I reactivated are much more strongly consolidated by way of sleep than those things I didn't. So that's the basic method of what we call tmr, Targeted memory reactivation. What they did was something very clever. They had them go through this process of the image rehearsal therapy. They were rehearsing the alternate ending, but about every 10 seconds they were playing them this very pleasing piano chord in the background and they were just bonding the association of the new outcome ending to the nightmare with this pleasant piano chord. And then sure enough, in the subsequent weeks afterwards, not only was that person day after day doing the diligent therapy practice of rehearsing the memory whilst the piano tone was playing, but then at night they would wait until they went into REM sleep, which is the state we think the emotional therapy begins, and they would start to replay that same piano chord over and over again. And sure enough, those people who had image rehearsal therapy standard, they improved by about 60% in their nightmare frequency reduction. Those people who did that plus the memory reactivation at night, it drove it from 66% all the way up to 92%. So now modern day neuroscience with its techniques is starting to overlap with classical clinical Psychology. And we're developing these next forefront of methods that really harness and fine tune the brain's ability to undergo effective therapy.

It's incredible. I mean, I think that we've known about classical conditioning for a long time, and the case of Pavlov's dogs is the most known of those. Am I right in recalling that this paired association way of bringing about certain memories or strengthening certain memories in sleep can also be accomplished with odors? That it's not just the playing of tones during specific experiences, but also, for instance, if one were to pair a particular odor with a certain novel memory event in the daytime or attempt to learn something new, that if that odor is then infused into the room of the sleeping person later that night, that somehow the memories would be strengthened. Do I have that correct?

There's nothing wrong. I've said it before, I'll say it again. Nothing wrong with your memory. That was one of the seminal papers that started this whole movement. And what they did was they had them learn this kind of perd associate card test, but they were wearing this mask, almost looks like a fighter pilot mask, and they were either puffing up inert air that didn't smell at all, or they were perfusing this very pleasant rose scent. Because smell in particular has a very unique relationship with our memory, in part because we emerged, you know, from animals that would principally use smell as their navigational tool. I think everyone has had this experience where you bond a certain cologne or a certain perfume with a particular individual. So they were puffing the rose perfume up the nose of these participants, and then when they went into sleep, they started to reperfuse that rose odor. Now, what was clever also about the experiment? You could say, well, look, just anytime you get something that smells puffed up your nose, your memory is going to be better. Now, the initial experiment had them learning the information when they're awake with the rose scent getting pushed up their nose. And then when they slept, they had the rose odor again. Another group had learning, but they had no rose smell pushed up their nose to bond with the information at the time of learning, when they were awake. And then when they slept, they also had rose odour stuffed up their nose, and they showed no additional benefit. So it's not just enough to have rose odor at night. You need to have made the initial bonded familiar connection with the novel information that you're learning to get the subsequent targeted memory reactivation benefit. And you could then think, well, practical tools, what should I do? Maybe, you know, when I'm Learning for studying. For a test, I should blaze up my, you know, my most preferred incense. And I'm. I have a particular proclivity to green tea incense, it turns out. And maybe then before I go to bed at night, I get a couple of sticks and I, you know, blaze them back up, tuck my head on the pillow, turn the light out. However, do not do that because it's probably a desperate fire hazard. So do not listen to me. But you could think. Think about doing something along those lines, perhaps. Anyway, so that's targeted memory reactivation.

Yeah, it's a perfect segue for what I wanted to talk about next, which is lucid dreaming. But before we move to lucid dreaming, I'm wondering whether or not there's an opportunity here to construct an experiment, maybe even a protocol of sorts, to uncouple the negative experience of nightmares to our daily experience. Could you. So, for instance, we're talking about paired association based on odors or sound replayed in sleep to sort of nudge or conjure particular daytime memories to the surface in the form of dream sleep. But we also know that one can uncouple associations. So, for instance, if one experienced something negative, maybe this is being attempted in the realm of trauma therapy and that experience was paired with a particular odor. It would be hard to do with visual cues and sleep or sound. Could one attempt to introduce a sort of a competing sound? You know, set up a sort of.

A collision.

Stimulus so that in sleep the dream would no longer contain the scary content or it would be less scary? Or is this exactly the wrong approach? Because if we believe that the nightmares are serving some functional purpose, allowing us.

To work through what you really don't want to do.

Right.

Okay, great.

Then we answer the question.

Well, no, I think it's unclear right now, but you're on the right line because there is something that we have in learning and memory called fear extinction. And let's say that I were to sort of classic Pavlovian learning, Pavlov's dogs, let's say I show you a specific image on the screen, and then you hear a specific tone, and then you get an electric shock. I show you the stimulus on the screen, you hear the specific tone, and then you get an electrical shock that I don't show you the stimulus on the screen, but you do still hear the tone. And then what happens is that you have a braced response to the electrical shock, and there's all sorts of combinations in between of that. But essentially, I condition you to learn that these things seem to be associated with a negative outcome, the inverse being the Pavlovian dog, which is that you ring a bell, you show the dog some food and it salivates. You ring the bell, show the dog some food, and it salivates, and then you ring the bell, you don't give it some food and it still salivates because it knows that the bell precedes the meat being shown. And I actually mixed my order around there in my own experiment to begin with. But then there's something different that you can do. You can start to perhaps change the sound or the bonded connection, and then you don't start getting the shock anymore. So that same ringing of the bell now is no longer consistently associated with the food. And gradually you decondition the dog such that after some time it learns, oh, I started to learn that the bell predicted food, but now it no longer does. And it takes some time to remove that. And that's what we call extinction. You've induced an association and then you gradually extinguish it by way of that alternate training method. So the question then became, could we use that type of method, but during sleep, could we train you up on a fear memory and then just begin the early signs of extinguishing, of deconditioning you? But then we don't do that very much. We wait until sleep and we continue the deconditioning protocol. And sure enough, sleep seems to be as if not more effective at extinguishing those fear memories than when you enact the protocol during wakefulness. So here is a very good example of where you can use this sleep dependent memory processing tapestry, this opportunity to harness not just to strengthen memories that you wish to keep, but start to extinguish memories you wish to remove. And so I think it's a very exciting. It's right on the cusp of what we're starting to do right now.

But I love it because I think some people would like to experience certain dreams and other people would like to not experience certain nightmares. Which reminds me of a tool that Rick Rubin taught me. I don't know of any experiments that support this directly, but I've tried this and it certainly has worked. First time and every time, which is Rick said, if you wake up from a dream and you want to remember your dream and or you found it pleasant or interesting, lay there completely still with your eyes closed and it will come to you. Whereas if you wake up from a nightmare, which many people do, and in a state of anxiety and you have a hard time shaking the the disturbing affect associated with that nightmare to move your body, get up and move your body and maybe even flip some lights on. Something that normally I don't suggest in the middle of the night, but waking up from a nightmare can be quite, quite disturbing. And it can be disturbing enough that it makes it difficult to fall back asleep.

And by the way, he's right. I don't know if he's read the science or he's just knowing Rick, he's probably just because he's so Yoda, like he's probably intuited supernatural levels of insight, tens of thousands of scientific articles, but he's absolutely right. One of the ways if you really wish to remember your dreams is not just jump up out of bed and start trying to write them down. Don't lie in bed, keep your eyes closed and gradually rehearse that dream over and over in your mind, almost as though you're scoring it into the etched surface of your memory. Trace more and more and gradually when you've re sort of capitulated and pieced back the jigsaw puzzle, then gradually open your eyes, start to dictate, start to write down. But don't do it immediately because as soon as you start doing it, it begins to float away. It begins to dissolve in a way that's, you're the sort of, you know, you're running and you're trying to reach your hand out. Exactly, yeah.

That's why I use the voice memos.

Last night I woke up in the.

Middle of the night from a dream and I decided to turn on voice memos. And I remember thinking, I'll remember this in the morning. And I remember you never remember this in the morning. There's a perfect segue for lucid dreaming, which is the awareness that we are dreaming well in a dream. Is lucid dreaming real? Can we train ourselves to lucid dream? And what is the value of lucid dreaming? Is it just a fun game we can play? Is there any, is there any reason we should attempt to lucid dream if we don't already or encourage more lucid.

Dreaming or even any reason we shouldn't? Perhaps lucid dreaming, you beautifully gave the definition. Loosely defined lucid dreaming is that you simply know that you're dreaming whilst you are dreaming. So in other words, as the dream is unfolding, you gain awareness of, ah, this is a dream, but I'm still dreaming at that moment. By science definition, you are in a state of lucidity. But most people don't really mean that when they say, oh, I'M a lucid dreamer, they mean. Yes, I become aware that I'm dreaming as I am dreaming, and then I take over the reins of control and then starting to decide exactly what it is you dream and and how you dream. So now I'm on the ground and I'm walking through a park and I decide that I just want to take off and I want to fly over the river or I want to fly out over San Francisco Bay and take a tour. So I decide to start flying. That is what most people think of as lucid dreaming. If you were to think about it. This thing called dreaming as we've described is utterly absurd as a state based on its psychotic kind of nature and characteristics. To then start to say it's that idiotic and strange and bizarre. But PS I can also take control of it and decide what I want to do with it injects a whole dose of disbelief into a process that's already unbelievable by itself. So science for a while just thought, this is charlatan type stuff that these people claim that they can control their dreams. How can you ever prove that? Because don't forget, when you go into REM sleep and you dream, you are paralyzed. So I can't just wake up and say I was lucid dreaming. That's not proof. I have to in some ways be able to demonstrate that I'm lucid dreaming as I begin to become lucid. But I can't because I can't communicate with you as the scientist. Well, it turns out that you can. One of the things we spoke about in the first episode is that, yes, you get these rapid eye movements. But think about what that means. I told you that when you dream, your brain paralyzes all of your voluntary muscles so that you can dream and dream safely and you don't act out your dreams. With the exception that at least two muscle groups, your extraocular muscles that move, your eyes and your inner ear muscles, for some reason they are spurred from the paralysis. So you can still move, otherwise you could never have rapid eye movements. So the eyes all of a sudden, because we have electrodes up top and below and left and right sides, we can measure what you're doing with your eyes during sleep. In fact, we have to do this to determine what Are you awake or are you in REM sleep? The brain activity by itself doesn't tell us that. We measure your muscle activity. And if you lose muscle activity and your brain is very active and the eye channels that we're recording start to show these darting back and forth signals, we know you're in REM sleep, that's how we define it. So that then suggested to us we can use the eye movements to create a form of Morse code signaling from the participant to the experimenter. And so let's say that with this claimed lucid dreamer who comes to my sleep center, we'll create a very specific, agreed upon code, which is that as you start dreaming, I can see that. And when you become lucid in that dream, firstly give me three leftward flicks of your eyes. We never see that in dreaming. It's a very deliberative act. And then when you say, okay, I've started the lucid dreaming and you've agreed with the experimenter that you're then going to start moving your hands, you're going to start to move your right hand. Well, when you start to move your right hand, give me four flicks to the right. And when you're moving your left hand in the dream, give me four flicks to the left. And so there we create this very specific instigational code. But then how does that help us? Well, we can have you sleeping in a brain scanner. And before the brain scanning session, when you sleep, I have you just go into the brain scanner awake, and I say, move your left hand and your right motor cortex is going to be lighting up. And then I'm going to say move your right hand and your left motor cortex is going to be lighting up. And for you and me, I build up a very unique map of your left hand motor memory representation and your right hand motor memory representation. And if it's the left hand, as I said, it's the right side of the brain, it's the right hand, it's the left side of the brain. So now I've got ground truth as to where your hand representation is on your motor cortex in my brain scanner. And then I'm gonna put you back in the brain scanner, let you go into sleep, let you start dreaming, then you give me three left flicks. Good. This person has now become lucid, and now he's doing four rightward flicks, which means he's clasping his right hand over and over again. And then he gives me four leftward flicks, which means he switched over. He's now using his left hand in his dream. By the way, I'm looking at the participant inside of the brain scanner through the glass. And of course they're not moving their hand. Why? Because they're paralyzed. But in the dream they are claiming, based on their Eye movements, that they are moving their hands. We bring them back out of the brain scanner and we analyze their brain scans during the period when they said, I'm moving my right hand, I'm moving my left hand. What did we see? Sure enough, we saw the same. And we being the royal, we, it's a great city by a German group. Sure enough, you see exactly the same pattern. It was scientific ground truth, evidence that when a lucid dreamer claims they are doing something in their dream, the brain scans that we received confirmed that indeed that's exactly what was happening.

It's just that none of the signal is being sent out to the periphery to the limbs, because there's that cut off at the spinal cord descending inhibition.

Yeah, at the level of the alpha motor neurons of your spinal cord.

Incredible. So here we are talking about lucid dreaming, which is a kind of mixed level of consciousness dreaming, of course, but also lucidity. That is an awareness that one is dreaming. Now, in just about every one of the five episodes leading up to this sixth episode in this series, you emphasize the key importance of deep sleep and rapid eye movement sleep. And in many ways, some of the problems that arise from waking up in the middle of the night too many times or being in shallow sleep as opposed to deep sleep. Lucid dreaming, it seems, is a kind of a case of light sleep because of one's awareness, or is it? So that's one the first question and then just very quickly, an anecdote. When I was a kid, I used to read these, like boys Life magazines and those kind of things. I forget what they called, but in the back they would have these ads for products like X ray glasses or sea monkeys, which turned out to be brine shrimp. What a disappointment that was. And I thought they were monkeys on the package. They were little monkeys, but they were brine shrimp. There was a product advertised that I in fact purchased, which was an eye mask that had a little blinking red light in one corner. And it said, learn to lucid dream. And the idea was that you would put this thing on and look at the red light just prior to going to sleep. And then you go to sleep with this thing on. And then at some point in your sleep, you would see or think that you saw the red light flashing. And the idea was that because you were in the eye mask, you were in enough of a dream that you would be able to link the waking state, recognition of the light, etc. Okay, people, get it. I purchased that product, I used it. I thought perhaps there was an Effect, quote, unquote, where I could lucid dream, but I wouldn't consider myself an avid lucid dreamer. Although sometimes I am aware that I'm dreaming, and usually it's in pleasant dreams, in which case I'm usually like, yeah, let's keep this going. Things like flying and being particularly talented in a sport that in my waking life I had minimal talent, things like that. Okay, so is lucid dreaming a case of shallow sleep and therefore something to avoid? Or is lucid dreaming something quite different? And is there any advantage to learning to lucid dream or enhancing one's amount of lucid dreaming? And if so, how should one go about that?

So I'll take the question, should you be lucid dreaming? And I think I can argue it both sides right now, and we don't have a very clear answer yet. The first sight is if you take a step back and ask, from an evolutionary perspective, let's assume, for want of a better word, that lucid dreaming is helpful, it's meaningful, and that we should engage in it. If that's the case, that it confers some type of evolutionary benefit, then you would expect that a lot of people would be doing it. But if you look at the statistics, somewhere between maybe just 10 to 20% of the population are natural lucid dreamers. And so from an evolutionary perspective, I could say, well, if it was so powerful, it was so meaningful, because we know everyone sleeps, and for the most part, we can say that almost everyone dreams. If that's the case, then those must clearly serve a purpose. But the fact that very few people are lucid dreamers, doesn't that tell us that it isn't necessarily beneficial? So from that perspective, I can play those numbers. There is an inherent flaw in my argument there, however, because that assumes, based on the argument I've just given you, that we have stopped evolving, and of course we have not. And so perhaps that 10 to 10 to 20% of the population who are natural lucid dreamers are at the forefront of hominid evolution and they're the next super. We shouldn't be worried about AI. We should be worried about the lucid dreams, because they're going to come and take over the world. So I can argue it from that perspective, which is just a philosophical argument. It doesn't have weighted data to it, but there is some data. Some individuals have asked the question, is there any changes to your sleep or even the benefits of sleep when you are a lucid dreamer versus not. And what's interesting is that for some papers, that have been published after nights when people report lucid dreaming, they wake up and they don't feel as restored, they don't feel as refreshed by their sleep in the morning. Suggesting, just as you sort of hinted at there, that the lucid dreaming state is associated with perhaps a less deep or more shallow form of REM sleep or a more active state of REM sleep, perhaps too active, so that it's fatiguing and depleting. And upon awakening you don't get that memory and that body, that brain and body reset. There are, however, a few papers that have not found that result. So I think right now we don't truly know if the lucid state is associated with unrefreshing sleep and unrestorative sleep. But if that proves true, then I think that that's one argument. The other argument I would put forward against it from that perspective would be think about what we've said regarding the functions of dreaming, memory processing, but particularly emotional therapy to gift us mental health. If we then come along and say, presumably, you know, nature through millions of years of evolution has come up with this, this blueprint manifesto of exactly what should be served up on the dream menu this evening, that's there's a reason for that. And that reason has been sculpted over millions of years to become wonderfully optimal for us and our emotional mental health. And then we come along in the space of a lifetime and perhaps you could argue a little bit hubristically, we think I perhaps know a little bit better than a couple of million years of evolution. I'm going to push those things off the rank ordering chart of what gets served up into my dreams and I'm going to supersede that and decide what I would prefer to be dreaming about. And again, I think that there's no good evidence that you could argue that that isn't true, but equally that it is true. We just don't know yet if that is the case, that lucid dreaming does produce unrestorative sleep. In some ways. It also begs the question, what. Well, what is happening in your brain during lucid dreaming? Is there anything in your brain that would explain why you don't feel refreshed? An early studies looking at lucid dreamers, when we put them inside of a brain scanner, I told you at the start of this episode, dream sleep has a unique brain signature. Memory regions, emotion regions, motor regions and visual regions, they're all lighting up. But then there's this one part of your brain that does the opposite, which is the lateral left and right sides of your prefrontal cortex, the logical rational thinking controlling regions of your brain. Those go offline. But early studies demonstrated that the activity, including the electrical activity over those frontal regions would be down as you were in non lucid dreaming. But then when people rise back up and said now I'm lucid dreaming with those leftward flicks, that activity was brought back online which makes a lot of mechanistic sense, which is all of a sudden the part of your brain that prevented you from having rational logical control has been re engaged and as a consequence you yourself can re engage in volitional dictation of the outcome of what you're dreaming. Some studies however have not replicated that finding because when they looked at it and they took out some sort of what we call these covariates or these confounding factors and I can bore you with what that principally is, it removed that result and all of a sudden the prefrontal cortex went back to seemingly.