transcript

Speaker 1:
[00:05] You're gonna go to sleep tonight, and you're gonna have dreams, but what if you could influence what you dream about? And as far as remembering what you dreamt about, what if you're spending years of your life in a world that you never recall? Can nightmares be manipulated as a therapy? And are dreams sometimes predictive of changes in your health before you become aware of those changes? Today we talk with Adam Haar Horowitz, a neuroscientist and dream engineer who is spending his working days trying to help people during their nighttime. Welcome to Inner Cosmos with me, David Eagleman. I'm a neuroscientist and author at Stanford. And in these episodes, we sail deeply into our three pound universe to understand some of the most surprising aspects of our lives. So last night, I had another dream, not uncommon for me, that I was about to give a big talk, and none of my slides made any sense. There was an audience of about 4,000 people, they were already seated, but I couldn't actually remember what I had agreed to talk about at this conference. And my computer was acting very strangely, nothing made sense, and I couldn't move stuff around on the slides the way that I needed to. So the clock was ticking down to my entry on stage, and there was a building tightness in my chest, and then bang, I woke up. And here's my normal life and all my responsibilities, and I got up, and within minutes, all of those details dissolved. The conference, the lecture hall, the computer, that pit in my stomach, all of it slipped away like I was trying to hold on to smoke. Now, this kind of thing where we are fully and emotionally immersed in some bizarre reality, only to come to realize a moment later that this was all false, this happens to us every night of our lives. And that's what we're going to talk about today. What exactly are dreams about? So let's start at the beginning. When you close your eyes at night, the world in front of you disappears. As you fall into sleep, your incoming senses drift away from you. And you might think that your brain goes quiet, but that's not what happens. Instead, your brain becomes a generator. And you find yourself somewhere else. You're running through a building, or you're talking to someone you know, but they have a different body, or you're in a bad situation that you need to get out of, or whatever. The key is that you are inhabiting a reality that feels completely real until you suddenly discover that it isn't. So what is going on here? Why does our brain construct dreams? There are several ideas in the literature, and like many things in neuroscience, the answer depends on the level of explanation you are asking about. So some years ago, I proposed a theory about why we dream called the defensive activation theory. The idea in a nutshell is that during sleep, when the planet has rotated into darkness, your visual cortex needs to stay active. Otherwise, given the brain's plasticity, your other senses will begin to invade that territory. So dreaming serves as a kind of internal defense mechanism, keeping the visual system active in the absence of external input. And in our published research, we find this allows us to make accurate predictions across different species of animals in terms of how much of their time they spend in rapid eye movement sleep. If you're interested in this, please check out episodes 11 and 51. Now, that's a mechanistic explanation about why the brain shoots activity into the visual cortex. In other words, it's about why the brain needs to make sure that the lights stay on at night. But I've always emphasized that the brain is a storyteller. So when your midbrain blasts random activity into your visual cortex, you don't see that as random pixels. Your brain weaves all of this into a sensory narrative. And the content of that narrative depends on what is in your brain, from what happened during the day to what's been burned deep down into your wiring based on all your experience in the world. And this is why you dream about your childhood home or some conversation you had or some fear that you have. And because the connections are much looser during dreaming, these stories can take off in bizarre directions. And this is the level that we're going to talk about today. And this matters because the content of dreams shapes how we feel the next day. It reflects what we are processing. Your dream content can rehearse threats or revisit memories. And sometimes when things go wrong, it can trap you in loops of trauma, which means dream content is more than just background noise. We're talking about experiences that you are having. You've got emotional landscapes that you're walking through. And given that you spend about a third of your life in this weird doppelganger state of sleep, it's sort of strange that you're having all this experience, but you remember almost none of it. So what if we could access more of that? And what if we could, at least in part, shape it? What if we could engineer our dreams? Now for essentially all of human history, dreams have felt like something that happens to us. They are mysterious and slippery and uncontrollable. But there's a growing field at the intersection of neuroscience and psychology and technology that's focused on what is called dream engineering. The idea is that we might be able to influence what we dream about and how we experience those dreams and what we recall. So just imagine being able to nudge your dreams toward the things that you want to dream about, like problem-solving or emotional healing. Imagine being able to reduce nightmares by reshaping them. These ideas are being tested in laboratories and translated into apps. And today we're going to explore that frontier. My guest is Adam Haar Horowitz, a researcher who's been at the center of this movement. His work spans from dream inception, in other words, methods for influencing your dream content, to interacting with your dreams in real time, to technologies for better recall of your dream content. Given that so much of your life is spent in this internal world, what would it mean to take it seriously? Here's my conversation with Adam Haar Horowitz. So Adam, tell us about dreams. What is happening when you fall asleep at night and you have these crazy cinematic experiences?

Speaker 2:
[07:34] I think dreams at night are basically thinking while you're asleep. And so for folks out there, I think thinking about your daydreams can be very, very helpful. What's that thing that happens when you stop paying attention in a lecture? Why is it you start imagining being on a beach in Hawaii? Why is it that you leave the place you are and you go to a whole different world? What is your brain doing? And so I think daydreams are the same thing as night dreams. The reason the night dreams are way, way weirder is because you're not also processing the world. There isn't all this input on top of that imagination.

Speaker 1:
[08:13] We're totally unanchored from the external.

Speaker 2:
[08:14] Totally unanchored, so a dream is what happens when you're completely untethered. Yeah.

Speaker 1:
[08:19] And what is happening in the brain when you make a transition into dreaming?

Speaker 2:
[08:24] Yeah. So there is this wild thing happening when you're transitioning into dreaming. It is a global process. So sleep happens, of course, in your brain, but your breath is changing, the way your eyes are moving is changing, your muscle tone is changing, your whole body is changing. Sleep is a global, dynamic, complicated process. People sometimes think about falling asleep as your brain turning off. It is absolutely not turning off. It is so complex. It is metabolically super active also. There's a lot happening. There's a lot of calories being consumed. And so when you start falling asleep and you don't have to process the outside world, you can start processing internal information instead.

Speaker 1:
[09:07] Yeah. You know, it's like these giant chip making factories, computer chips. They switch over the whole factory to manufacture something else. And it's this enormous process where they're switching everything over. And I think about the transition into dreams and into sleep more generally as being this giant turnover.

Speaker 2:
[09:27] Whoa, let me give you an example, which is so fun. When you fall asleep, one of the things your brain has to do is clear out waste products from during the day. Because all this thinking, using all this ATP, all this adenosine triphosphate, the energy that your cells use, it leaves behind waste products. And you have to clear them out, just like you have to clear out waste products from your gut. The distance between your neurons will increase by 60% every night that you fall asleep, so that you can wash away that metabolic waste. So literally, falling asleep, it's that weird. It's like your brain is expanding to have these waves of fluid come through and wash you clean from the thinking of the day. It is a crazy beautiful process.

Speaker 1:
[10:11] Excellent. So let's go into dreaming in particular, that cinematic, emotional kind of thing. Now, traditionally, that's been thought to happen during rapid eye movement sleep, when you can see when you're watching somebody sleep that their eyes are moving back and forth beneath their eyelids. But tell us the modern view about when we're having those cinematic, emotional dreams.

Speaker 2:
[10:31] Yeah. So the consensus in the field now is that we're dreaming all night. We're not just dreaming in REM. And it is true that if you want those biggest, emotional, most cinematic dreams, you're most likely to get them in REM. But you're most likely to get them in REM at the end of the night. So like the most fun thing, if I tell folks, oh, you want to have big dreams, snooze that alarm. Why? Because you're most likely to have super dense REM right there in the morning. But also it looks like in those last two hours of sleep, your non-REM dreams look very cinematic, look very emotional, look very vivid, have first-person narratives. They're hard to distinguish. So I think the big takeaway is you're dreaming all night and sleep staging needs to get a little smarter to track those dreams. But if you want to make a good bet and you're watching a partner or a kid sleep and you want to get a big dream report and you see those eyes moving, it's a good time to wake them up.

Speaker 1:
[11:25] Cool. So why are dreams so bizarre?

Speaker 2:
[11:29] Great. So I think you can't answer this question without asking about what dreaming is doing in general. And so I like a theory called the Next Up Theory, which is the network exploration to understand possibilities. And this is Bob Stickle and Tony Zadra, two wonderful scientists. And the basic idea is that, okay, we go around all day collecting all this information into short-term memory, but somehow that information has to leave short-term memory and get integrated into the story of our lives. And you can't do that integration while you're processing the world around you. So you're too busy taking information in into short-term memory, things that are happening to you right now, processing the world, the physics, the possibilities, the dangers. At night, your eyes are closed. At night, you're still. You don't need to be doing any of that work. So what you're doing at night is taking that information you learned today and fitting them into the memory networks of your whole story of your life, in particular, so you can predict all the possibilities of what's going to happen tomorrow and next week and a month later. So we're having this conversation. I'll store it in short-term memory. But it kind of reminds me of that time that I got interviewed to get into high school to have this exam, it was kind of intense and emotional, but it's like a little bit like this in my stomach, it kind of feels stressful, but it's like not that stressful, it's like kind of different. I have to understand the similarities and the differences. So maybe tonight I have a dream, and that dream is you and me sitting here, but you're my high school counselor. And so at night, I'm associating these things, largely based on emotion, so dreams are largely emotion driven, and I'm trying to fit these memories together so I can make sense of the story of my life. Because our job isn't, and you know this as a neuroscientist, our job isn't to store all the information we've ever gotten from the world. Our job is to extract patterns. Extracting patterns relies on making associations. Those associations are driven by feelings. This is something that Antonio de Mazio writes about so beautifully in The Feeling of What Happens. Dreaming is the same thing. Dreaming is a feelings driven association to make sense of your day. And you can do it because you're not processing all the potholes and hot coffees and things that are in front of your face while you're awake.

Speaker 1:
[13:39] Great. And so this is what the field calls consolidation, where you take all this stuff and you burn it into the rest of the system. Okay. So the reason that dreams are so bizarre is because of these weird associations that are happening while you're stitching the stuff into what you already know.

Speaker 2:
[13:56] Yeah. So the reason I think dreams are so bizarre, you can think about as a kind of network or node association, a kind of tree of exploration. The first thing you want to do with this interaction, us sitting here together, is think of the most similar memories. Oh, okay. Sitting here is sort of like how I sat in the chair this morning and they feel a little bit similar. Okay, I'm going to associate those two memories. But the longer you spend asleep, the more times you have an Ultradian cycle, the more times you wake up and go back to sleep, the more bizarre those things are going to get, so that you can understand the most wild and wild and wild possibilities of what might happen the next day. And the idea here is kind of simple. It's that you want to have the widest net of possibilities so that you're not surprised when you wake up the next day by what happens. You want to be able to predict everything that happens tomorrow. And so tonight, I rehearse all the possible scenarios that are similar to this. And the idea is simply that being surprised costs you a lot of calories. You have to learn. But if you've already predicted tomorrow how something's going to feel, what it reminds you of, so that you're not surprised the next time you sit down in an interview, it basically isn't as surprising and doesn't cost you as many calories to understand it. So dreaming is a way to explore short-term, long-term, less bizarre and more bizarre associations between a memory and experience, and all the possible experience that it could be like so that I can predict them happening.

Speaker 1:
[15:28] What about nightmares? What's the story with nightmares?

Speaker 2:
[15:30] Yeah. So the idea is that dreams when they're working well, are a way to integrate today into the story of my life and make it make sense. Memory consolidation, keeping memories, memory evolution, extracting patterns from those memories and gist from those memories. Nightmares are when that memory consolidation evolution breaks. So the canonical nightmare that folks in my field worry about, are these trauma-related nightmares and they're often treatment-resistant. And so what they look like is somebody has an experience and that's a traumatic experience. And these dreams are weird because they're not a metaphor, they're not a narrative and they don't change. People have the same experience at night that they had during the day. And it's like that memory is not evolving. It's like you're going back, he was chasing me down the hall with the knife, just like he did in real life. And every night, I go to sleep and I know that he's going to chase me down the hall with the knife. So I actually got into this field because I had a traumatic experience as a little kid, a violent mugging experience. And I had these traumatic nightmares and a therapist and my mom really helped me with it and helped me by basically telling me bedtime stories. We can get into how that works in a second, but I had a personal experience of these nightmares. They happen every night and so that memory can't evolve, that memory can't lose its emotional power, that memory can't be integrated into the networks of your whole life story. It just returns every night and it's like an exposure every night. And those nightmares are really stressful. You can see that they're stressful all the way from cortisol levels to them predicting levels of suicidality and depression and dementia and Alzheimer's. Nightmares are really, really, really bad for you. And so they're a treatment target. But I think of nightmares basically as that memory integration system not quite working and instead getting stuck on the memory because it's so emotionally charged.

Speaker 1:
[17:30] And let's zoom in on that for a second about predicting dementia. Tell us this quite surprising result.

Speaker 2:
[17:35] It's really interesting. So, this is a research mostly from a person named Obedemi Otaiku. The takeaway is that across dementia, across Alzheimer's, across even early death before 75, if you ask people on a set of questionnaires called PSQI, which you ask everyone about their sleep quality, there's this one question. Do bad dreams make your sleep worse at night or keep you up at night? If they endorse that, if they say, yes, bad dreams keep me up at night. People seven years later are more likely to have cognitive decline. Fifteen years later are more likely to have Parkinson's. They're more likely to die early. The reason is kind of obvious, which is that during the day, if you spend a lot of your time stressed out, we already know it has all these consequences in terms of inflammation, in terms of physical health. During the day, it's not weird. We think, oh, my psychological health affects my physical health. Being stressed out up here changes my whole body. We know that. It's a treatment target. We haven't really figured out the link between stress at night in dreams and stress in the body. But it looks like where your body should be repairing, whether it's your immune system at night or fighting inflammation at night, instead you're rehearsing the worst moments you've ever had and going back to them. So there are these consequences in terms of brain health, these consequences in terms of physical health.

Speaker 1:
[19:03] Is there a way for us to know the arrow of causality there?

Speaker 2:
[19:06] Totally. So, I mean, the thing you can do is you can look at confounding factors. So these things that I mentioned, oh, nightmares and stress streams predict cognitive decline dementia. Those are independent of depression, anxiety. Those are independent of sleep quality and sleep efficiency and sleep duration. You can be sleeping the right amount of hours, but these nightmares are the distinguishing factor in terms of whether you are or not going to have cognitive decline later on. So one of the ways you look at is confounding factors. The better way to determine causality is help with the nightmares, see if it changes things. So the kind of amazing punchline is there's a behavioral therapy called imagery rehearsal therapy. You take the nightmare, oh, he was chasing me down the hall with the knife and it was nighttime and I was running and you stop and say, hey, what if it was daytime?

Speaker 1:
[19:57] You ask the patient this during the day during a therapy session.

Speaker 2:
[20:01] You're sitting with them and they tell you about their nightmare that they're having every night. Okay, he's chasing me down the hall with the knife and it's nighttime and I'm running. Okay, what if it was daytime? They say, no, it wasn't daytime. No, no, no. Okay, but we're going to try to change it. And you write down, okay, chasing me, but it's daytime. And then you rehearse it and then you repeat it and then you write it down again and you rehearse it. And before bed, they rehearse it again and you do this.

Speaker 1:
[20:24] Rehearsing, you mean they think through that scenario?

Speaker 2:
[20:26] That's right. They really imagine it, really imagine it, chasing, but it's daytime. Do it for three or four nights, and eventually the nightmare will change. They're still getting chased, but it's the day and they will wake up and they will say, oh my God, it's not happening to me. I'm making that dream. I'm making that nightmare. And so there's this sudden shift in agency, what people call self-efficacy or internal locus of control. I'm in control. I'm not a victim of my nightmare every night. And anyway, it's not happening to me. I'm making it. And so then, often what will happen is people will stop having the nightmares entirely. But also, there's a difference between having nightmare and being distressed about the nightmare. And saying I'm in control changes everything about distress. So in terms of causality, it is very clear that, for instance, helping people with imagery rehearsal therapy, changing their nightmares, changing the level of joy in their dreams, will predict, for instance, suicidality a day later, a week later, six months later, is really important for waking behavior.

Speaker 1:
[21:44] One more question before we move on to the next thing. I have nightmares occasionally, not very often, but when I do, they're not predicated on real memories. So how does that fit with the story that you mentioned about a memory that's embedded?

Speaker 2:
[21:56] Yeah, totally. So I think it's useful to think of these trauma-related, repetitive nightmares as pretty distinct from the nightmares that all of us have sometimes. And then also within that, dream science says a bad dream happens all the time to everyone, the majority of dreams are negative actually, 70% of dreams are negative. It seems like we're rehearsing a lot of threats, because we're like, oh, if you're going to rehearse something that might happen tomorrow, it makes sense to rehearse the bad thing, because that's the thing that's going to cost me a lot tomorrow if I don't think about it. But these repetitive nightmares seem damaging in a way that normal nightmares aren't, and normal nightmares, we say a nightmare, is the dream that wakes you up. A bad dream that you have and you sleep through the night, even if it feels really bad, that's not called a nightmare in terms or a clinical nightmare disorder. Nightmares disturb sleep. Nightmares disturb your life. They disturb your waking behavior. They make it so you can't work. They make it so you can't think. They affect rumination. They return during the day. A nightmare disorder is distinct from the bad dreams we're all having, naturally.

Speaker 1:
[22:58] So what are the approaches? What are the therapeutic approaches that one can take to nightmares?

Speaker 2:
[23:03] Yeah, I'm just going to say my favorite recent one. So Beyond Imagery Rehearsal Therapy, which is wonderful, and it's a behavioral therapy that works for many people, but not all, we need new innovative treatments. This repetitive nightmare complaint is something you can see in 80% of PTSD patients. It is huge. It is huge. If you think only of, for instance, folks who are veterans in post-combat nightmares, this is millions of people we're talking about every night, nightmares. So big deal. My favorite recent one is Pilar and Sika, Boris Heifetz and Harrison Chow, folks out of Stanford Medical School here, actually where you are, who are just great, doing this crazy innovative thing. What happened was people were coming in for surgery, a normal surgery that had nothing to do with their PTSD. They happen to have PTSD. They happen to have these repetitive nightmares. They go under.

Speaker 1:
[24:01] Anesthesia.

Speaker 2:
[24:02] Yeah, for the surgery. Propofol anesthesia in particular. And these people wake up and they say, Oh my God, I just had the best dream I've had in years. It was like my nightmare, but it didn't go bad. It was like this thing that happens to me every night, except that there wasn't any of the negative emotion. And they wake up and they say, I haven't had a joyous dream in years. Thank you for giving that to me. And then, three months later, six months later, two years later, they no longer endorse PTSD. They no longer have traumatic nightmares. Just from one session of propofol anesthesia, they are not having these trauma related nightmares anymore. And so Boris and the team were like, this is crazy, it keeps happening. I think that we're gonna really investigate this and we're gonna use propofol. And it turns out, if you look at propofol dreams, everyone's having dreams under anesthesia. And if you look in particular at the content, they're about 95% positive and joyous. Doesn't matter if you come in endorsing PTSD nightmares or not. They're super joyous dreams. And so for somebody who hasn't had a good time in their head for a long time, that's a big deal. And so they're exploring this kind of as a new psychedelic treatment mediated by anesthesia. The reason this is really cool is because millions of people are getting anesthesia today. And millions of people are not getting MDMA treatment today, if you think that's useful for PTSD. But this is something that's already happening. And all you have to do is change a little bit of the outset of propofol, extend it a little bit, and ask them what they're dreaming about quietly. Don't interfere with it as they're coming out of surgery so that they remember it, because otherwise they'll lose this pleasant experience if you don't ask them in the right way. Just like in the morning, if I wake you up with a loud alarm and I say, you got to get to work, you'll forget your dream. So you have to help them recall that dream at the end of surgery if you want it to be beneficial.

Speaker 1:
[25:59] Great. And we're going to come back to this issue of dream recall in a few minutes. And you're also doing some nightmare work.

Speaker 2:
[26:05] Yeah, I'm really moved by the nightmare problem. So we got to do some work with Dr. Wesley Youngren, who's wonderful. He's a Marine himself. So he has an understanding of what it means to be in combat. He has an understanding from his community of what it means to take that combat home with you after service and the ramifications mental health-wise. And so Wesley had this great idea, which was basically, okay, imagery rehearsal therapy, beautiful treatment, but a lot of people don't believe it's going to work. Like, yeah, right, doc, you can change my nightmares BS. I don't believe you for a second. So treatment credibility really matters in all kinds of behavioral therapy. So he said, OK, OK, I'll leave you alone at night. You can go to sleep, but I'm not going to do anything. But just come in for a nap. And come in for a nap, and we're going to try to choose something for you to dream about. Maybe a tree, maybe a fork, maybe Beyonce, maybe chocolate. I don't care. Come lie down on the couch. You use a method called targeted dreaming abation, which is something myself and some friends at MIT came up with. The basic idea is you let people slip into the sleep onset period. They're half asleep, so they're losing a lot of their cognitive control, but they can still hear. When they're half asleep, you literally play the words to them from a speaker. Remember to think of a tree. Remember to think of chocolate. You then let them slip into the lightest sleep. It's called covert REM. It is at sleep onset, but it looks REM-like in terms of the dreams. You then wake them up and say, what were you dreaming about? And they say, oh, in a river of chocolate with oompa loompas. Then you say, okay, you can go back to sleep now. And you repeat it, repeat it, repeat it. And you wake them about five times. They nap for about an hour.

Speaker 1:
[27:50] How do you wake them gently?

Speaker 2:
[27:51] You wake them gently with really, really quiet audio. I've done vibration. I've done smell. I've done all this stuff, but simplest is sound. And you just say, hey, tell me what you're dreaming about.

Speaker 1:
[28:00] Oh, the sound of your voice saying, what were you dreaming about?

Speaker 2:
[28:03] That's it, yeah. And so this is via an app that we've made. This is recorded sounds. So people fall half asleep. Remember to think of a tree. They fall into covert rem to have a dream. You wake them up, what were you dreaming about? And then you snooze, rinse, and repeat, do it again. And so then, take in 100 people, about 92% of them will have a dream of that thing. And this is, we've done these studies at MIT, independently replicated at Duke, folks at Harvard using it, folks at Montreal Medical, Vancouver General Hospital is replicated.

Speaker 1:
[28:38] And this is called Targeted Dream Incubation.

Speaker 2:
[28:41] Targeted Dream Incubation, the targeted, yeah, just because you can pick a target like tree. So the important thing in the context of the work that we did with Wesley Youngren at the VA is people then wake up from that nap and they say, oh damn, maybe you can change these dreams. And so treatment credibility is of interest, but what we really focused on is these feelings of agency. And we saw this 24% increase in people's ratings in terms of feeling of self-efficacy or agency. And then we saw that was related to lower suicidality, the day of and lower suicidality a week later. So just making someone feel less helpless about their dreams and nightmares has this real clinical impact. Super cool. And so all these strategies, imagery rehearsal therapy, NSC's are dreaming, targeted dream incubation, we're coming up with a whole menu for this really important thing.

Speaker 1:
[29:34] Oh, incredible. Okay, so let's zoom in on the hypnagogic state, which is right when you're falling asleep. So some people like Thomas Edison and Salvador Dali would actually use this, take advantage of this. So tell us how they did that.

Speaker 2:
[29:51] Totally. So pick your Edison's or your Dali's, but also you can read Proust and you can read Nabokov and you can read all these poets and playwrights and scientists playing in this little area of sleep onset, the Beatles and Einstein and whatever. So it's the moment when your brain is turning thoughts into images. It's the moment where your brain is turning the outside world into an internal world. You're awake, you're asleep, but it's not a switch. Sleep scientists think there are nine stages of the descent into sleep. They're called Hori stages and they're quick.

Speaker 1:
[30:24] How do you spell it?

Speaker 2:
[30:25] H-O-R-I. It's named after a guy named Tadao Hori. There's a bunch of amazing Japanese dream researchers. I'll tell you about them. In those nine stages of sleep, you have these kind of different stereotyped dreams. You have these very specific brainwave features, EEG features. And hypnagogia is the state of transition. The kind of cool thing about it is you're neither here nor there completely. So for people listening, this is the state when you're falling asleep and you're like, uh, I've got to go to the grocery store and I've got to pick my kid up from school. And I've got to be in a bouncy castle with my grandma. And you're like, wait, no, wait, wait, wait. It's where your thought takes a left turn all of a sudden. And it's quick and it's very, very, very strange. And if you want to play with it, you can extend hypnagogia and it will only get weirder the longer you stay in it. It is a crazy state of mind.

Speaker 1:
[31:24] How do you extend it?

Speaker 2:
[31:25] So I extend hypnagogia with serial awakenings at sleep onset. So very, very simply, you can, for instance, without any sort of brain imaging, if you just snooze 10 times, especially over a nap, because naps are going to be very, very REM-like during the day.

Speaker 1:
[31:41] As in hit your snooze button on your alarm.

Speaker 2:
[31:43] You just keep hitting that snooze and those dreams will get weirder and weirder, but you will also get more control over those dreams. So we haven't gotten to talk about lucid dreaming yet. But lucid dreaming is this idea that you could, in a dream, know that you're dreaming, and then choose what to dream about. And so this is something that's been documented for hundreds of years, but actually was researched again at Stanford, most seriously by a guy named Steven LaBerge about 50 years ago. And it's the idea that in this covert REM early sleep period or in REM, you realize you're dreaming, you take control of the dream, you make a choice, but even crazier, if you are awake inside a dream, you're totally paralyzed, right? Of course, you can't move your body or else you would wake up and start running around the bed and fighting ninjas. But your eyes are not paralyzed in REM sleep. They can move around. So in that lucid dream, the experiments work like this. Somebody realizes the dream, and you've agreed before, hey, when you realize it's a dream, move your eyes left and right in the dream. Look at the giraffe, look at the elephant, look at the giraffe, look at the elephant. Your real eyes of the person lying there will actually move left, right, left, right four times. So you can signal from inside the dream, I know that I'm dreaming.

Speaker 1:
[32:57] When you say four times, you mean that was the pre-agreed upon number to do.

Speaker 2:
[33:01] How crazy is that? So they are completely in a different world. They are asleep. We are on different planes of consciousness. But they're looking around in their dream, one, two, three, four. Their actual eyes are moving one, two, three, four. We register that on what's called their EOG. Looking at their eye movements.

Speaker 1:
[33:17] It looks like little lines.

Speaker 2:
[33:18] That's right, totally. And then you can go a little crazier. Okay, they know they're in a dream. I'm going to play a math problem on the loudspeaker. What's three minus one? In their dream, they'll be walking down the street and then they'll look at a house, and it'll be house number three minus one. And they'll say, oh, it's the math problem I knew I would get. And then they'll move their eyes, one, two, and they'll answer correctly. This is a paper, kind of Karen Conkley and a bunch of folks led this a few years ago, replicated across four different labs. They are asleep. They are in a different plane of consciousness. You are playing math problems over the loudspeaker. They're answering correctly with their eyes while they remain in REM. And this is like, it's cool science, but it's also the first time humans have ever communicated across these planes of consciousness. So as someone who's really interested in consciousness and phenomenology, like for you, this is pretty weird. It's like, we're talking across worlds? So I really love it, via the eyes.

Speaker 1:
[34:19] I love that. Okay, so that's lucid dreaming. But zooming back out now to this hypnagogic state, right when you're falling asleep. So you're about to tell us what Edison, Dali and all the others actually do to take advantage of this.

Speaker 2:
[34:32] It's true. I got a little excited about dream research. I took a left turn, gotten to lucid dreaming. So yeah, they would do something really simple, which they call the steel ball technique or sleeping with a key. But both involved, sitting up right, like you are, letting yourself take a nap during the day. Especially good is what's called the post-prandial period, which is a fancy way of saying after you eat lunch, because you really get sleepy. And you fall asleep sitting up, but you're holding something heavy. When you start falling asleep in hypnagogia, all these things are happening in your brain, but also you're losing muscle tone, so your grip will loosen. You'll drop that ball, it'll hit the ground and make a loud sound, and you'll catch hypnagogia. Edison called it his genius gap, because hypnagogia is super associative, super exploratory, super creative, super flexible cognition. And so Edison would pick a problem he was working on, think about it as he was falling asleep, and catch his hypnagogic thoughts around that topic to find his most creative thinking. And totally cool that Edison did it. Interesting, it's been documented, but we just got real scientific evidence for it. Led by Celia Lacau, a wonderful paper called Sleep Onset is a Creative Sweet Spot. And what she found is that, have people try to solve math problems, specific kind of math problem that needs a eureka moment, like solving puzzles. Have them do this exact technique, and they enter into N1, and they wake up. Or have them sleep a little deeper and let them go into N2, a different stage of sleep. The people who just dipped into N1 have a 3x greater likelihood of solving that creative problem than the people who dipped into N2 and went deeper in. There is something sweet happening in N1. There is something strange and specific and flexible and creative. And I know you've written about creativity. There is something associative happening in that state of mind, but you got to catch it if you want it. So that's what the steel ball was for. And that's actually what our work at MIT around Dormio, which was basically a wearable device, which would track the same thing, you losing muscle tone and then would talk to you. It's really similar to the steel ball technique, except instead of waking up entirely, it would help incubate that dream of your problem you wanted to work on right at that moment. It would wake you up automatically and record a verbal report, and then it would say, great, you can snooze again, because the ball is kind of hard to snooze again with a steel ball.

Speaker 1:
[37:12] Okay, great, so now let's talk about dream recall. So what happens with almost all of us is we wake up in the morning and we think, oh my gosh, I had this dream and this happened, that happened, and then it's like gossamer, and within 15 minutes, we can't remember it at all anymore. So first of all, why do we not recall our dreams? And then we'll get into how we might.

Speaker 2:
[37:34] Totally, so there's a few things that we do every morning that make it pretty likely we're not gonna recall our dreams, which is we wake up to a really loud alarm, which doesn't let us leave sleep gradually. It makes us leave sleep suddenly. We start thinking immediately about what's on the phone, the email, the New York Times, oh my God, what is he doing now? All of that is gonna invade our thoughts and overwrite these really gentle bits of dream recall. But there's another reason we don't recall our dreams, which is we don't care about our dreams. So in the same way-

Speaker 1:
[38:06] Evolutionarily.

Speaker 2:
[38:07] Yeah. So in the same way, if I decide, you know, birding is really important because knowing what birds are around my city will help me understand climate change. I will walk out of this recording studio today and suddenly I'll see birds all around me and I'll remember those birds. I decided they were important, so I noticed them, so I remember them. You have to make things important. If you want to encode them, consolidate them and keep them. We don't care about dreams culturally, but I can tell you if somebody is in a dream study and we say, hey, we're investigating this thing, it turns out dreams, this is true, it turns out dreams and specific kind of dreams are prodromal. So before a syndrome, they can predict for instance a manic episode or a depressive episode. So we really want to keep track of your dreams. Suddenly dream recall, boom, it spikes because he made it important. And so if tonight you go to sleep and you say the first thing I'm going to do in the morning is I'm going to record my dream and then I'm going to share my dream with my wife and she expects me at the breakfast table to have this conversation with her because Mark Blackgrove's research shows that sharing dreams creates more marital intimacy than sharing waking thoughts. That's true. Because of that, I'm going to keep it or because there's research which shows how useful sharing dreams with a therapist is in terms of introspection. Pick your reason, your dream recall will spike. So these two things, how we wake up in the morning, too stressful, too invasive, you move too much, how we go to bed at night, I don't care about dreams, why would I remember them? You can set salience, you can set meaningfulness of dreams before sleep and you will completely change your dream recall.

Speaker 1:
[39:52] Let me just return to this question about why under normal circumstances we don't remember our dreams because one idea of course is that it's a bunch, you're sticking your head in the night blender and you've got all these activities happening, but you don't want that to actually interfere with your memories of how the world works. You don't want that to actually build your internal model of the world. How do you think about why generally we don't remember unless we put a lot of effort into it?

Speaker 2:
[40:17] I think it's really hard and I know you like to think of things both culturally, socially and evolutionarily. I think it's very, very hard to tease these two things apart. The reason being, I've been super, super lucky to spend some time in indigenous context, for instance, where dreams are deeply important to people. Dream recall there? Everyone's remembering dreams every day. I think there's a cultural question as much as there's an evolutionary question. I think the big reason we don't remember dreams isn't because of, oh, necessarily there's some way that our brain works. I think it's because we don't care. I'll give you another example. Canonically, there's no smell in dream reports. I expect this is the case with you. Oh, I've really primarily visual dreams. I have a lot of motor. I run around, things happen, people attack me. But I'm not smelling stuff in my dreams. That's not why I wake up reporting. But again, if you go to a space where smell is incredibly important, specifically a tribe called the Anges in the Andaman Islands, where smell is a way of interacting with your world and spirits and ancestors, the Anges, majority of them, their dreams are smell. I think it's a dream is related to the thing you think is important about your world. And we live in a very visual world. Because of that, we have very visual dreams. Because of that, we have visual activity in dreams. Because of that, we can even read dreams out in the visual cortex, and we can predict what someone is dreaming about really well. But I think it's a cultural question. There is, you're totally right. Lots of people in the memory field think, oh, dreams are so bizarre and weird. They do their work and we don't need to remember them for them to do their associative work. But I don't think that totally explains it. Because there are these other groups of people who are recalling their dreams every day, and they don't have different brains than us. They have a different culture.

Speaker 1:
[42:09] I take that point about dream recall. I'm slightly more skeptical about the smell part only because when we look at what are called PGO waves, which are from pontine to geniculate to occipital cortex, that's why it has this heavy name. But the point is, it's the set of waves driven by a very evolutionarily ancient part in your midbrain that blasts activity into the visual cortex and only the primary visual cortex. So that's why dreams are visual. Here's the thing, it splashes out from the visual cortex and maybe if you're a culture that emphasizes smell a lot, then certain things are associated. So it follows some pathway and triggers a smell.

Speaker 2:
[42:51] 100%. You're totally right. And I'm stoked that you know about PGO waves. So on the PGO wave thing, totally. But the thing you need to answer that question is a brain imaging study of the Anges and the Andaman Islands to see actually what their sleeping brain looks like and if it's the same or if it's different. So totally, maybe, oh, cool, we have PGO waves and we have visual cortex, then we have olfactory bulb activation, and we can see the kind of generation of their dreams. Totally. Maybe they sleep really differently. I don't know. Could be pretty interesting. I see you don't buy it.

Speaker 1:
[43:20] I don't buy it only because we radiated out of Africa and moved to different places like yesterday, but the human brain hasn't changed in that time. So, and in fact, these PGO waves are conserved all through the animal kingdom. Everybody's dreaming this way.

Speaker 2:
[43:40] Totally.

Speaker 1:
[43:41] But I do think, I do take your point that if smell is really important to your culture, then you'll have more paved pathways between visual cortex and olfactory. And so maybe that'll get triggered more.

Speaker 2:
[43:53] And you can do fun things with that. You can say, oh, you know, I really want to make a new musical album. And I know that the Beatles had their best songs come in dreams. And I want to use my dreams creatively. And so I'm going to fall asleep listening to music from this album that I'm starting to create, so that it's more likely that I have a dream which is sound based, so that it's more likely that I have a creative breakthrough in my dreams. So you can do some kind of picking around this. You can pick, for instance, oh, I want smell as a signal that influences my dreams. So I'll give you a really crazy study. I mean, I'll give you two smell studies. I'll see if you like them. They're very, very different. One of them, you can pick smells. I smell them, I smell them, I spray them, I associate them with-

Speaker 1:
[44:43] Like lavender or something.

Speaker 2:
[44:44] Lavender, rose. I associate them with a place. And then I spray that smell on my pillow. I'm much more likely to dream of that place. You want to dream of Paris? Spend the next week. I'm going to watch a little Paris video while a scent is in the room. I'm going to spray that same scent on my pillow. I feel very confident you will have a dream in Paris.

Speaker 1:
[45:02] I thought these studies were done a long time ago.

Speaker 2:
[45:04] So long ago.

Speaker 1:
[45:05] And okay, but maybe I misremembered. I thought they hadn't yielded positive results.

Speaker 2:
[45:10] Yeah, so the study that I'm referencing is 200 years old. It's a guy named Saint Denis, who would go with the piece and he would spray scents and then he would spray the one on his pillow and he would go to the place. And then people have had some trouble. How does it work, this association, where we're getting better and we're getting better and we're getting better at it? And I'll give you a really, really specific example of this protocol, which is basically, I'm going to associate a signal, it doesn't really matter if it's smell or sound, with something. Then I'm going to reintroduce that thing in sleep, then I'm going to hope that somebody dreams of that thing, and then I'm going to see how it changes their next day. So there's a paper from this year, again from Karen Conkley, whose work I love. You have people look at a set of puzzles while they're awake. You then, while they're looking at this puzzle versus that puzzle, play sound A versus sound B. You then wait until they're in REM sleep. You then play sound A versus sound B. What you can see is that playing sound A, about 75% of people will have a dream of the puzzle related to that sound. Not only will they have a dream related to it, but they'll then do better at solving that puzzle than folks who didn't have that reactivation related to it. So we're getting really good at not only making a claim, oh, we can associate a sound with something in waking life and then make you dream about that thing, but making you dream about that thing will then make you better at tasks related to it. We did the same thing with creativity. Make someone dream about X, test them on X. Someone else dreams about Y, test them on X. The first person will do about 43% better on a set of creativity tasks. And it is hard to do causal work in consciousness. You have done this for a lot longer than me. But we're getting close. Dan Dennett wouldn't be satisfied, but we're getting close.

Speaker 1:
[46:59] Yeah. Why wouldn't he be satisfied?

Speaker 2:
[47:02] Because I think that some people think you can't solve the epiphenomenon problem. You can never make a claim about consciousness. Even if you say the experience seems to change waking behavior, somebody would say it's not the experience, it's the neural mechanisms that create the experience. I think there's basically no difference. And that's an argument for philosophers. What we're supposed to do is make useful stuff.

Speaker 1:
[47:26] Great. Okay. So that was back to dream incubation. But the other end of it that I want to drill in with you is about dream recall. Okay. So you've developed an app called Dust. Tell us about that.

Speaker 2:
[47:40] Totally. Can I say one thing before? And thank you for asking about it. So on dream recall, the best sci-fi scenario is, actually, we don't have to wake people up and ask them about their dreams because self-report is unreliable. The sci-fi scenario is what if we could just look at their brain activity and tell what they were dreaming about? Great. In the same way that sci-fi predicts science in so many fields, Horikawa, wonderful researcher, has this paper encoding visual imagery during sleep. And he shows that what you can do is you can show people a bunch of pictures, flash them really, really, really quickly while they're awake, and look at their visual cortex. This is an fMRI paper. It's a functional magnetic resonance imaging paper, so a kind of brain imaging where you look at brain blood flow and oxygenation in parts of the brain. But the very simple idea is flash a bunch of pictures of people while they're awake, let them go to sleep, look at their brain activity in the visual cortex, and look at similarity. When they looked at a giraffe while they were awake, this part lit up. Looks like that part is lighting up when they're asleep. And you can guess with really solid accuracy what they are dreaming about.

Speaker 1:
[48:48] And it's because you're looking across the whole visual cortex and you're seeing patterns. And so, right, giraffe is represented by a particular pattern across all these voxels, which are three-dimensional pixels in the brain. You know, some are very active, some are a lot in between. And anyway, you can look at this and that's how you figure out these things, right?

Speaker 2:
[49:12] And you can now do this. There's a paper from this year, actually, from Monica Schoenhauer, which is doing this just with EEG. So fMRI is this big magnetic million-dollar machine, scary, intense, expensive. EEG, pop it on your head with a bunch of electrodes, electroencephalogram. This is the classic brainwaves. It looks like a heart rate base, like doom, doom, doom. You can put people to bed, have them listen to one of four bedtime stories. You can then look at their brain activity while they're listening. When they go to sleep, look at their brain activity and you can guess which story they listened to. So it's getting reactivated just on EEG. And the stronger the similarity to the story, the more likely that they are dreaming of that thing with condition blind raters saying, oh, this person just looking at their dream, can you guess what story they listened to? Just looking at their brain activity, can you guess which bedtime story they listened to? And so we're building up to the stage where we can think, huh, not only can we control what someone dreams about with bedtime stories, we can then see them dreaming about it with brain imaging. We can then tie that reinstantiation of the experience to waking performance, encoding, consolidation, creativity. We're building the IO, that input-output system for dreams. And it's totally, it's totally, it's crazy. It's like a crazy moment in the field.

Speaker 1:
[50:36] Yeah. Okay. So now let's return to dream recall. Okay. So you wanted to help people get better at recalling their dreams because otherwise, unless you live on some island somewhere where that's important, it's very easy to not recall them. So what did you do? What is the Dust app? Yeah.

Speaker 2:
[50:53] Thanks for asking. Yeah. So the Dust app says at night, we're going to have classes on dreams and tell you why they're important in particular, that then turn into practices so you can try incubating a particular dream. So we have classes for flying dreams. You want to have a flying dream? Give me 15 minutes before your bedtime for the rest of the week, we'll give you a flying dream. We have classes on imagery rehearsal therapy if you're struggling with nightmares. We have insomnia classes, lucid dreaming classes, yoga nidra classes. But the whole point of the classes is basically to make you think that your dreams are important, so overnight you're more likely to encode them. But then in the morning, use our alarm instead of your native Apple iOS alarm. It'll wake you up really gently. And it'll say, tell me what you're dreaming about. You don't have to move. You speak out loud. You stay still. It'll record your dream report, store it in a journal, and then ask, hey, do you want to snooze or do you want to wake up? And you can snooze. After that snooze, you can choose a dream incubation. Hey, remember to dream of flying so that when you're half awake, half conscious, not quite there, it'll guide your dreams towards a particular theme. So it takes both the targeted dream incubation protocol we talked about, takes the targeted memory reactivation protocol we talked about, and it squeezes it into an app so you can use it at home. Use it for your nightmares. Use it for your creativity. We're seeing big jumps in dream recall, which is really, really fun. Because, like you said, if you don't remember these things, you can't work with them.

Speaker 1:
[52:29] And when you record your dream content, what happens with it then?

Speaker 2:
[52:33] Totally. So it lives in a dream journal, and then you have choices. You can analyze your dream. You can look at what Gestalter, Freudian or Buddhist approach to it, or you can look at what a more contemporary cognitive neuroscience approach to understanding that dream would be.

Speaker 1:
[52:51] And that's done by AI.

Speaker 2:
[52:52] That's done by AI. You can also track over time. Hey, who am I dreaming of most? What places am I dreaming of most? What stress dreams am I having? You can also look at your dream readiness score. So in the same way you can be like, man, you didn't get much sleep last night. You're probably gonna be really sleepy tonight. You should be really careful about your bedtime. You can also look at, oh, you had pretty disrupted REM the night before. We think you're gonna have a super vivid dream tonight. I think that you should make sure not to drink a glass of wine and stay away from the blue light so you can have a big beautiful experience tonight. So you can look at your dreams over time. You can look at your dream readiness. And the dreams over time matters because across all these different symptoms, pick your motor symptoms in Parkinson's or your bipolar disorder or your depressive episodes, a sudden change in dreams is a clinical signal that's super meaningful. And so if you see this sudden change in dreams or you see this sudden change, for instance, in acting out your dreams, it's really something you should know. But you're not really going to know that if you haven't been tracking your dreams over time and suddenly they're all really violent, for instance, or suddenly they're all dreams of death, for instance. And so useful for a psychiatrist, for instance, if they're working with someone who might be struggling with suicidality. Oh, there's this sudden change, dreams related to death. We're going to be really careful in the coming months, etc., etc. So it's a way to understand your dreams over time, to understand yourself.

Speaker 1:
[54:19] Might it have something to do with biology? I don't know the answer to this, but if you get a viral infection, might your dreams change?

Speaker 2:
[54:26] Yeah, it's an awesome question. So there's so much different work on this, but maybe the closest work to that kind of question is the work around lupus. So before you have a flare, before you have your first flare, often people will have this sudden change in dreams. The kind of pain they're going to experience a few months later, they'll have it in their dreams before they have it in waking life. These are called prodromes. This is not that surprising. It sounds a little weird, but basically the idea is that you're having changes already in your body, but they're very subtle and they're overshadowed basically by all the things you're processing in wake. But at night, you're much more in touch with your body because you're not overshadowed by input. And so that little, little bit of pain or little, little bit of change is going to manifest as a dream. So if you're having a lot of dreams of your teeth falling out, which is a classic, it predicts you having some dental problems six months later. This is not that surprising. If you want to have some really messed up dreams tonight, just wait until 11 PM and eat really spicy food, your stomach is going to mess your dreams up. Like we live in a brain that is connected to a body. It's just like those two things aren't disconnected. That's sort of surprising to people because dreams are like ethereal and untouchable. They're not, they're coming from your stomach. So, in the prodrome space, that means, my girlfriend has lupus, so I've thought a lot about this. That means that, huh, you have this sudden change, your doctor should know about it. I have some folks I'm related to who struggle with Parkinson's. That means that if you have a sudden change in your dreams, they're suddenly more violent. You're in your 50s, all of a sudden, you're having these dreams where you're getting attacked, and you're kicking, and you're fighting. It's likely that those dreams, so those dreams predict onset of REM behavior disorder, which predicts onset of Parkinson's. If you know that Parkinson's is coming, this is a decade, this is 15 years out. Take that to your clinician, that is so valuable. So yes, you asked me, oh, maybe if you have a viral infection or a fever, could those little changes in your body manifest as dream content? Definitely, all the way from tooth changes to a dopamine disorder.

Speaker 1:
[56:35] Amazing. So let me return to two things. One is the curiosity question. I often hear people say to me, oh, I have the exact same dream every night. And I've wondered, how would you actually know if that's true? Because often when I have a dream, some bizarre thing, I think, oh, I've been here before, but it's presumably not true that I've had that same dream. So if you're looking at a dream journal, you could actually answer the question, what do people find?

Speaker 2:
[56:58] I love this question because dreams mess with your feeling of familiarity.

Speaker 1:
[57:03] Yeah.

Speaker 2:
[57:04] Beyond creating some strange visual world. I mean, as brain scientists, we have to think of how weird it is that my mother can be a chair in a dream and I'm like, yeah, she's a chair. She's always been a chair. Something about familiarity is all messed up in a dream. And so the idea that you could step into a dream and be like, oh, this is familiar. I've been here before. I don't really believe you. Totally like you said. So if you dream journal over the course of months, you might find, for instance, you're having a dream of your boss yelling at you a lot. That's probably something that you want to work through during the day. You're really returning to this place a lot. Let me give you a more concrete example. One of the Dust users is in her 70s, and she's a beta tester, and she's using the app, and she has not been recalling her dreams before. She starts using the app, she starts remembering her dreams, and she sends this report into the team. She says, I've been waking up in the night with my heart pounding for so long, and I don't know why. I'm remembering my dreams suddenly, and I'm having this dream almost every night. It's about my parents, and my parents are yelling at my brother, and I'm a kid, and it's 60 years ago, and they're being cruel to him. Basically, she goes back to a difficult moment in her childhood. Every night she wakes up from it, heart pounding. But she didn't remember the dreams until now. Suddenly, she recalls the dreams, and she writes in in her report, this is some anger that I think is actually with me during the day that I was pushing down, that I'm going to take to my therapist, and I'm going to work on, and I'm going to process. But I didn't remember the nightmare before, and so I didn't know that's why I was waking up at night. And so dreams, you know, whether you're a psychoanalyst, or you're Salvador Dali, or you're Proust, or you're at the temple of Asclepion in ancient Greece, people are saying the same kind of thing, which is dreams are a place where more subtle signals can surface than our introspection during the day. We are more in touch with ourselves and more in touch with the world, and we're more aware of quiet and small signals and so we can really see what it is we're processing, really see what it is that's important to us. And so tracking your dreams over time, whether it's a nightmare like this user, whether it's a stress dream of your boss, or whether it's, you know, man, I'm really having a lot of dream of Instagram ads. I should probably stop scrolling at bed and falling asleep. So this is crazy. 50, this is a survey study across 1000 people. 54% of young Americans, 18 to 35, regularly dream of advertisements. Well, it's pretty crazy and dark, but the reason is they're falling asleep, scrolling on their phones, and they're getting hit with these things. And the CEO of Netflix says, my main competitor is sleep. They are trying to push further and further into the sleep onset period. So they're basically doing targeted dream incubation, but with the most sticky million dollar content you can think of. So people are dreaming of ads. If you dream journal and you're having like a bunch of Hayley Baber dreams, you should probably be like, I probably shouldn't do this at night. I probably should be doing more of my own work than letting them get me.

Speaker 1:
[60:14] Okay. So in closing this part, tell us why dream recall matters.

Speaker 2:
[60:18] Totally. It's sort of like asking why thinking matters. Thinking is where I figure out who I am. Thinking is where I figure out what's important to me. Thinking is how I make my choices about what to do tomorrow. Dreaming is your thinking at night. It is your most private and personal space. It is a world made entirely by you. So it's an important place to introspect. It's an important place to reflect and find yourself. But just a simpler reason is that you're dreaming in all stages of sleep. You're sleeping for 26 years of your life. If you decide, dreams don't matter. I'm just going to let them go. You're giving up years of lived experience where you could be flying. You could be sitting with a lost loved one. You could be sitting with your grandma across the table. You could be returning to childhood memories. You could be choosing joy. And instead, you're like, I'm just going to lose that huge part of myself. And so one of our users wrote this really beautiful thing. He said, I feel like I've been sleepwalking through sleep for my whole life until now. Suddenly getting dream recall means you find a new part of your mind.

Speaker 1:
[61:24] Is the unpredictability of dreams something that's useful? And if we were to engineer our dreams 100%, would we be losing something?

Speaker 2:
[61:32] Totally. I think it's an awesome question. It's an ethically important question. I think there's no chance of engineering your dreams 100%. In the same way that like, you know, what is education if not trying to engineer people's thoughts 100%? It is really, really hard to put a thought in there the way you want. You know, you're planting a seed, but in the soil of their mind. I mean, you're raising two kids. It's like you're planting a seed, but that kid's a garden. You're going to grow into something else, man. And so I think dreams are like that. I feel totally comfortable. You come to lab, I can make you dream of a tree. But is it the tree from your childhood, or is it the tree that you think of when you look at your calendar and, oh gosh, I got to water the trees? I have no idea. Plant a seed is all I can do.

Speaker 1:
[62:15] What did you think of the movie Inception?

Speaker 2:
[62:18] Love Inception. I think Inception totally rocks. And the biggest thing it did was make the world think about their dreams more and make them think dream incubation was possible. So when people come into lab, I just say, oh, it's kind of like that Inception thing. And they say, oh, great, cool, I've seen the movie. I know exactly what's about to happen.

Speaker 1:
[62:33] Last question, what does dream engineering look like in 10 years?

Speaker 2:
[62:37] So dream engineering is what we've named this whole field. So, you know, Dr. Harrison Chow, who's working on the anesthesia dreams is calling himself a dream engineer. But also Michelle Carr, who's working on better versions of imagery rehearsal therapy, she's calling herself a dream engineer. It encompasses a lot of folks who are doing everything from chemistry to behavioral techniques. So my hope is that in the same way you can go to a sleep clinic, you go to a dream clinic. For a really large portion of insomniacs who come into a sleep clinic, those people do not have a sleep problem. They have a dream problem. They are sleeping the right amount of hours, but the whole time they're in N2, which is about 50% of the night, they're having anxiety dreams. The dreams are, I wish I could fall asleep, I wish I could fall asleep, I hope that I fall asleep, but they're literally asleep that whole time for hours. As they wake up and it's called sleep state misperception. All the people coming into an insomniac clinic saying, hey, please fix me and the doctor says, you're actually sleeping seven hours. That's a dream problem. I want dream clinics for those people. All the people with PTSD who are coming, repetitive nightmare, what percentage of them actually go to a clinician? Less than 10%. Great. I want these tools, these dream-engineering tools on every phone, in every bedroom of a person who's struggling. There's these other areas we didn't even talk about. In substance use disorder, for people who dream of a substance, that predicts relapse onto that substance. All those people on their phone, they should have imagery rehearsal therapy to help them with those dreams. Across insomnia, across addiction, across depression, across PTSD, across prodromes for Alzheimer's and prodromes for Parkinson's. I hope that dream-engineering is a way to make the world care. And then to give them an easy tool, as easy as the tools we have for meditation. Hey, give me 10 minutes of your time to do a few techniques before bed, and we'll change that internal world you have, make it a little more joyous, make it a little more vivid, make you live a little more of those 26 years.

Speaker 1:
[64:40] I have a conversation with Adam Haar Horowitz. In neuroscience, we often think about the work that dreams are doing in the background, like consolidating memories and exploring possibilities and stitching together the threads of our lives. But at the same time, there's the question of the experience that we're having. Because even when we take a mechanistic view, like the defense of activation theory, where dreaming keeps the visual cortex active, that still leaves open the question of what the experiences mean for us. In other words, what they feel like and what they do to us. And that's where Adam's work with lots of his colleagues in dream engineering, that's where that work comes in. Because it's pointing to the fact that dreams are part of our mental life and a part that largely gets ignored. We can live our entire lives treating dreams as disposable, things that evaporate in the morning. But what happens if we shift that stance? What happens if we decide that this internal world matters? Once we engage with it, other possibilities open up. We can begin to notice patterns that might not be obvious during the day, like recurring themes. And we can begin to reshape experiences like nightmares by introducing small changes. We can begin to use dreams as a space for exploration, for creativity, for problem-solving, for reflection, and maybe we can start to see dreams as continuous with waking thought, part of the same process of the brain modeling itself, and its past, and its possible futures. And the larger horizon is that as dream engineering continues to develop, we're going to increasingly find ourselves in a world where people actively shape their inner experiences during sleep. We'll have dream clinics, and dream interventions, and dream-based diagnostics. I think there will be a lot of questions here as we move forward, like if you could guide your dreams, how much should you? Maybe unpredictability is part of what makes dreaming useful for allowing unexpected associations. So there will be questions about what is gained and what is lost. But the big picture is this. You spend a huge chunk of your life in this state, years and years of experience, worlds built and dissolved every night, conversations, fears, flights, reunions, all of it unfolding in the dark. So given that that much of your life is happening in a place that you rarely remember, what might you discover when you start paying attention? Go to eagleman.com/podcast for more information and to find further reading. Join the weekly discussions on my sub stack and check out and subscribe to Inner Cosmos on YouTube for videos of each episode and to leave comments. Until next time, I'm David Eagleman and this is Inner Cosmos.