The Dreaming Brain with Matt Walker

22:18Neil deGrasse Tyson:That is. Just to understand the question. Is it that the brain is processing your awake state? I was going to say your woke state, but that's got baggage today. Your awakened state, and does your brain know that that is an objective reality versus what it dreams about? Is that where he's trying to get at here? I think what he's saying is that all of reality is a perception of our brain. So when we go to sleep, does that kind of perceptive reality then just become neural noise or does it serve a purpose to reveal the machinery more clearly? That was good. That was good, Chuck. Great question. Wonderful synopsis.

23:06I would say what this question to me reveals is an uncomfortable truth about your dreams, which is that your brain can build an entire universe. So space, time, faces, emotions, memory, narrative, coherent, out of nothing. There's no light hitting your eyes. There's no sound. There's no world. You're cut off from reality. but in the dark of this thing that we call our skull it is manufacturing a fully convincing reality and it does it every single night and that has an implication because if the brain can do it when essentially the doors are closed what makes you so sure that what you experience when your eyes are open don't mess with us like that now stop messing with us i'm gonna have to go further because the reality is it actually isn't any different than that so what we call reality right now is also a construction it's a model that your brain is building behind your eyes and the only difference is that the waking perception is it's almost like a controlled hallucination one that's essentially tethered to time second by second by second and that information is streaming from your senses.

24:28That's the only difference between your waking consciousness and your dreaming consciousness. My name is Neo.

24:39Neil deGrasse Tyson:Yeah, you're coming in and out of the matrix there, just in case you didn't know. Programs, hacking programs. Yes. But no, so it's a wonderful demonstration that I think there's there are these hard boundaries that we think of that are actually much more porous than we imagined that there's this thing called the dreaming state and the waking state they're very similar in some ways except that dreaming has a feature to it that really gives it away which is that you have no logical rational reasoning or control and that's why you start to believe things which are not there. So you hallucinate, you are delusional, you get confused about time, place in person, you're suffering from disorientation.

25:25And then how wonderful you wake up in the morning and you forget most, if not all of that dream experience. So you're suffering from amnesia. If you were to experience any one of those five things, when you're awake, you'd be seeking some psychological treatment. But for reasons that we now understand based on the patterns of brain activity, when you go into dreaming, this seems to be a normal biological and psychological process. And the principal reason that dreams are the way that they are is because the thing that makes us most human, which is called the prefrontal cortex, that part of the brain, unlike the rest of the brain, the brain lights up when you go into REM sleep.

26:02In fact, some parts of your brain are 30 % more active than when you're awake, which is stunning except for the prefrontal cortex. That goes offline. So now you have these emotional centers, these memory centers, the visual centers, the motoric centers of the brain, they're all active. But the prison guards, they've left the building and the prisoners are running amok. And that's the beauty of dream sleep. There is no sort of CEO in control with top-down regulation. There's no logical, rational control. The inmates are running the asylum. Basically, that's exactly what it is and we believe that there's good utility to that that's where you get kind of the loosey-goosey everything starts to get connected together in these wacky strange ways no wonder you can solve problems in your sleep in a way that you can't with this very rigid way of thinking that is the waking state wow now you've scared me yeah that's however that's so your

27:04Neil deGrasse Tyson:dreams were the world's first psychologist first of all right they were exactly it is your therapist Yes, your therapist. Inner therapist. Inner therapist. Wow. What you just said there, Matt, actually answered Aaron Gannon's question as well. So, Aaron, thank you for your question. So, let's move on to Sam who says, Greetings, Dr. Tyson, Lord Nice, Gary, and Mr. Walker. My name is Sam, and I'm writing to you from the home of Casey Jones, Jackson, Tennessee. Is that right? Look at that. He says, I recently read a study by Laura Lewis from the Boston University about cerebral spinal fluid washing the brain during sleep.

27:48My question is, Dr. Walker, could the waves of cerebral spinal fluid that wash through the brain during sleep actually be generating the dream state rather than the other way around? And if so, what does that mean for what we think dreams are for? Thank you for your time and consideration. Live long and prosper. Well, thank you, Sam, you big nerd.

28:17Well, I mean, just generally, what is this cerebral spinal fluid and its relation to sleep? Because Sam has already read the study. We have not. So maybe if you start there, we'll be able to unfold an answer for him. Does it have any validity? Well, that's that, that, you know, whatever you know about it, does it have? An immense amount of, I think it's one of the most stunning new discoveries in the field of sleep. Wow. We used to think that the brain didn't have its own cleansing system. The body did, which is called the lymphatic system. And we've known that for several centuries in fact. But then a scientist at the University of Rochester, Makin Nedegaard made an incredible discovery working in mice.

28:59First, she found out the brain does have a cleansing system. It's called the Glymphatic system, named after the cells that make it up called glial cells. The second thing that she discovered is that this cleansing system, which uses cerebrospinal fluid, this sort of, it's almost like the WD-40 of the brain. It uses the cerebrospinal fluid to essentially flush out all of the metabolic detritus that builds up during the waking day. And that was her second discovery. This glymphatic washing cycle is not switched on in high flow volume. across the 24-hour period. It's only when you go into sleep and specifically deep sleep, and this will come back to Sam's question, it's only when you go into deep sleep that this cleansing system kicks into high gear.

29:44So it's good night, sleep clean. It's a power cleanse for the brain. The final thing that she discovered, which makes it really relevant for disease states, is that two of the pieces of metabolic detritus that the glymphatic system cleanses when you go into deep sleep are beta amyloid and tau protein. these are the two underlying culprits of alzheimer's disease and it explained why for now over 10 years and we've done some of these early studies we were seeing a very strong relationship between people who were getting less than six hours of sleep across the lifespan and a markedly higher risk for developing alzheimer's but it was an association in search of a mechanistic causal answer and she discovered it and we've now actually developed a silent fMRI science MRI scanning protocol and we're having people sleep inside the MRI scanner and we can now see this pulsing cleansing system in real time wow as people are sleeping in the scan it's absolutely beautiful but it actually comes back to Sam's question though which is it turns out that dreaming comes from principally a different stage of sleep it comes from rapid eye movement sleep, whereas this glymphatic system happens during deep non-REM sleep.

30:58So the two are disconnected. But while we're here, because we keep referencing stages of sleep, I think it'd be nice to have a baseline and you give us the actual stages of sleep. And how many cycles would that happen throughout the night, these stages themselves? So when everyone's head hits the pillow tonight, you're going to go on this incredible rollercoaster ride in and out of different stages of sleep. And as I mentioned, we have two main types of sleep, non-REM sleep and REM sleep. Now, non-REM sleep has been further subdivided into four separate stages, unimaginatively called stages one through four, increasing in their depth.

31:41So stages three and four, that's that really deep restorative sleep. So what happens is that when you fall asleep, you go into the light stages of sleep, and then you go down into the deeper stages of non-REM sleep. And after about 70 or 80 minutes, you'll start to rise back up and you'll pop up and you'll have a short REM sleep period. And then you go down again, down into non-REM sleep and then up into REM sleep. And you do that on average, about 90 minutes is each cycle's length. What changes, however, is the ratio of non-REM to REM within that 90 minute cycle as you move across the night. And what I mean by that is in the first half of the night, the majority of those 90 minute cycles are comprised of lots of deep non-REM sleep and very little REM sleep.

32:28But as you push through to the second half of the night, that teeter-totter balance, that shifts. And now more of that 90 minute cycle is comprised of REM sleep, dreaming sleep, and very little deep sleep. And that's the reason if you've been woken up from a phone call at sort of one o 'clock in the morning, you almost never remember a dream. but if it's late in the morning sort of five six seven in the morning and you get woken up typically that's when you'll remember a dream because you're moving into the REM sleep rich phase of your night of sleep does that make some sense absolutely so by the way i discovered these cycles

33:02Neil deGrasse Tyson:when i was in college when i was studying my sleep cycles right and so at 90 minutes is a bang-on unit of time for me if i if i don't have time to do five and a half hours i can 90 minutes i don't even need an alarm so you get an hour and a half come back out correct and i have several of these throughout the night which are hugely useful when you when you are apportioning the times of day where you got to get stuff done versus when you're going to go to sleep but i would say though to your point neil i i love the fact that you you can almost get that quartz like precision there is a bit of a myth though that i say on average it's 90 minutes it can be as little as 70 minutes and it can be as long as 120 minutes, depending on who you're studying.

33:47Neil deGrasse Tyson:Got it, I'm not 120. If I wake up after 120, I'm groggy. But if I wake up after 90, I'm not. Perfect, because you've gone down into the deep stages of sleep again. I discovered this empirically is my point. Yeah. You know how I did it? Did I say this the last time? I don't know. Are we going back to my meth joke? No, no, no, no. Please don't. So what I did was I drank like, you know, half a gallon of water. Oh, that's the Native American alarm clock. And then I went to sleep. And then throughout the night I woke up to go pee. But my body woke itself up to go pee. And those were bang on to the cycles.

34:28Neil deGrasse Tyson:When I'm in deep REM, it doesn't wake me up. So I made note of those timings. And then that's how I used to explore. So that's just me. I don't know. I'm the one who was hit by lightning, apparently. Well, I've done the same thing, except it's just my failing prostate. Oh, it's happened to me. Did you need to share? What I love about it is, you spoke a little bit about if I go past that 90-minute mark and I then wake maybe an hour and... It doesn't work. 45 minutes, it doesn't work. It doesn't work. Because, as you said, we've gone down to that other cycle. And when you come out of deep non-realm sleep, That's very unusual.

35:07Your brain never naturally does that. And what happens is that when you go into deep sleep, a large amount of cerebral space, particularly your frontal cortex and other areas, they all go power down. And it's almost as though when you come out of deep non-REM sleep, you try to go from the basement to the penthouse and you get stuck on the 13th floor and you get this grogginess. It's almost like a sleep hangover effect. Yeah. And it's what we call sleep inertia. And when you come out of deep sleep, it takes much longer for the brain, like a classic car engine, for example. It just needs time to gradually warm up before you get to operating temperature.

35:43Which uses, I was just about to go, I love it, you know?

35:48Neil deGrasse Tyson:Sympatico. You and me, Neil. The value of this to me is, often I take very early airplane flights, so I gotta leave home at four to catch a six o 'clock plane. If I'm up till midnight or something, or if I'm working, I can combine two, one and a half hours, that's three hours, I'm not gonna go to sleep at midnight and wake up at four, because that's out of sync. So I will stay up another hour so that I will wake up. So that you'll come out of it. Correct. And you'll come out of the cycle at the right time. At the right time. And so sometimes it's staying up another 15 minutes or 20 minutes or a half hour.

36:26Neil deGrasse Tyson:And so this works with precision. Thank you, what's the term? It's quartz, quartz precision, I love that. Quartz like precision. But I would say that people sort of have this, you've got to be a bit careful for these kind of gadgets that say, I'll wake you up at the perfect moment because they all assume the average 90 minute cycle. But the problem is no one is the average. Well, I'm the average, but yeah. Well, except, except the sublimely extraordinary, but yet average. Can you all digress now? Okay. Feel better now? Next question. All right, we've got Kenny McFarlane. Mofarlane, really precious about pronunciation.

37:06Kenny's from Washington, D.C. And thank you, Kenny, for sharing your own personal story here. We're going to get the thoughts of Matt. As a kid, I experienced a number of parasomnias, sleepwalking, sleep terrors, nightmare disorders, sleep paralysis. Still some occur. Why do we grow out of these conditions? Why do some seem to go away and others continue to be consistent? does our brain chemistry change and that allows for them to cease or better what does experiencing parasomnias tell us about our brain chemistry uh thanks for taking the question you're welcome and he cites himself as an all too lucid dreamer oh wow yeah so much going on in the question okay i'll try and be efficient but what can he's describing are the parasomnias so these are parasomnias these are things that happen sort of in and around sleep but aren't quite sleep itself so sleepwalking sleep talking night terrors people often think that if someone is sleepwalking or they go over to the refrigerator they open the door they kind of have some that they must be dreaming and they're just acting out their dreams that's actually not the case when you have a sleep walking or sleep talking event sleep eating event what's happening is that your brain is in the deepest stages of non-run sleep and we can record it and we can see people walking around enacting these what seem like complex behaviors, but the brainwaves look like deep, slow brainwave sleep.

38:33And what they're doing is simply acting out fairly routinized, just simple kind of more sort of basic motor behaviors. And if you wake people up, and typically you shouldn't, you should just sort of make sure that they're safe, but just let them go through it. But if you wake them up and you say, what was going through your mind just before I woke you up? And they'll say, nothing. My mind was blank. And the reason is because they were in deep dreamless sleep. They weren't having a dream.

39:00Neil deGrasse Tyson:So going to the refrigerator is different from asking to start a game of chess, right? Well, you said they tend to do routine. You open the window. Exactly. Something that is very repeatable. Yes. Yep. These are, this is not sort of, well, some people have enacted things such as they get in their car and they actually drive and but most of this happens much lower down the sort of the food chain of of basic behaviors however sleep paralysis is something a little bit different and i will get to the kenny's question as to why does it change as we get older why do we have less of these events but sleep paralysis is a beautiful demonstration of how normally two things go lockstep hand in hand which is that as we're waking up well let me go back when you go into dream sleep, your brain paralyzes your body so your mind can dream safely.

39:57So every time you go into dreaming, there's a signal sent down your spinal cord and it paralyzes all of the voluntary muscles, not the involuntary ones that keep you breathing, but the voluntary muscles that you use to kind of reach over and grab a glass. All of those are paralyzed. But normally when we're waking up out of a dream, your consciousness as it's starting to return to you, as that's starting to come up, the paralysis is gradually released in perfect lockstep so that you wake up and you can move and you can talk and you don't even think twice about it. Sleep paralysis happens where your consciousness gets a little bit ahead of its skis and you're starting to wake up but you've not being released from the paralysis.

40:42So you can't move, you can't talk, but you're aware of your surroundings. And typically this happens with a sense of something else or someone else being in the room. And it turns out that if you look at all of the characteristics of sleep paralysis, they often explain quite a large majority of so-called alien abductions. Correct. Because when was the last time anyone here had this new story? You know, they were saying today in downtown Dallas, Jimmy was just whooshed away by aliens. You know, we were sitting around the board table and all of a sudden, whoosh, Jimmy was gone. It never happens like that.

41:19It's usually at night when we're in bed, people describe that the aliens injected them with a paralyzing agent. They couldn't move. They couldn't talk. They couldn't fight them off. This is classic sleep paralysis. And so this is one of the other features. It's not sleepwalking or sleeptalking. It's a distinctly different sort of component of this broad collection of things that we call the parasomnias. Why do these things, however, change as we get older? Well, it turns out that the boundaries between sort of waking consciousness and these sleep events is quite porous when we're young. And in part, it's because of the prefrontal cortex developing.

41:58the more that your prefrontal cortex develops, the more capable your brain is of creating hard boundaries between being awake and being asleep. But when we're younger, because of that prefrontal cortex not yet being fully matured, the states of being very much kind of awake and conscious versus being very much asleep and non-conscious, they're a little bit more sort of free flowing. And that's why you can have intrusions of essentially wakefulness into sleeping states. And that's what we call parasomnias. Now, as we get older, we can still maintain some of these things. And I think Kenny is describing that he still has some of these things too.

42:38That's fine. It doesn't mean that there's anything necessarily wrong with you as long as it's not causing safe issues. It just means that your prefrontal cortex never developed, Kenny. Not saying that at all. You have no executive function, Kenny. I'm sorry to tell you, Kenny. You're not medically trained enough to die. Matt just told you. Kenny, you're fine. Kenny, you are absolutely golden. As long as there's no safety concerns, you are A-OK. However, wouldn't it depend on how old Kenny is? Because from what I understand, the prefrontal cortex and executive function is the very last thing to harden in the development of the brain.

43:14It is. And that's why essentially these things can even be extended into late teenage years. and I would say to Kenny's question too I think he mentioned sort of is it something about the chemistry of the brain it's not really the chemistry of the brain it's the structural architecture of the brain that's changing and that's why those episodes will start to dissipate the further into adulthood we go because of the structural development rather than the chemistry itself by the way stress and sleep deprivation both of those markedly increase the probability of those parasomnia clustering events happening, just as an FYI.

43:51Interesting.

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45:42All right, here we go. This is Ana Ivinko. And Ana says, hi, Dr. Tyson, Dr. Walker, Lord Nice, and Gary. Greetings from Croatia. My name is Ivinko, and I have a question about the importance of sleep scheduling. I work as a doctor in the emergency medicine department, and my shifts are as follows. 12 hours, day shift, 7A to 7P. Night shift the next day, 7P to 7A, and then one day of rest. Often I work two day shifts, and then a night shift for two nights, and then a day shift. How do I preserve my circadian rhythm, and therefore my physical and mental health on this job? I really like my job, but I also want to live long, long time fan and recent Patreon patron.

46:29And yeah, so why don't you go ahead, Matt, and tell Vinko that she is screwed. No, no, would you stop?

46:36Neil deGrasse Tyson:She needs a union, that's what she needs. A union. You need a union, girl? You need a union? Anna, Anna, Anna, oh my goodness, okay. For a start off, what is a circadian rhythm? Circadian rhythm is simply a rhythm that lasts approximately one day. So circa diaz, sort of essentially the circling of one day of time. So that's your circadian rhythm. We all have one. And it's almost like this sinusoidal sort of wave where we are more awake throughout the day because we are a diurnal species. And then our biology ramps down as we go throughout the night. And then we step and repeat it. And you have a circadian rhythm.

47:12It's driven by a 24-hour clock in your brain. And it just beats out that beautiful 24-hour rhythmic pattern.

47:18Neil deGrasse Tyson:Okay, briefly, I heard that they took people underground and took away all their watches and had them just live their own understanding of day and night. And when they did this, they lived 25-hour days. They didn't live a 24-hour day, none of them. So that we might be fighting our own rhythms by staying with the sun. Are you familiar with that study? Was it replicated? What was that about? It is. It's been one of the most replicated findings. and rather than think of it that we're fighting our biology, it's simply that our biology has a little bit of sort of error margin in it, and it simply needs the sun, which has been the most consistent signal since the dawn of time, for a rhythmic circadian rhythm.

48:05And it latches on to the sun, and the sun acts like a set of fingers on a wristwatch, and it simply just kind of tweaks your 24-hour rhythm back to precisely 24 hours, each and every day.

48:17Neil deGrasse Tyson:Okay, so we're not fighting a 24-hour day. The sun tunes us to it, and without the sun, our circadian rhythm gets sloppy. It's a little rayward. It does. It runs, on average, for most people, it runs about 24 hours and about 11 minutes. So it's different for different people, but on average, that's... So you drift forward in time by a little bit each and every day. So we need a leap rhythm. A leap rhythm. We need to insert a leap rhythm. Yeah. From what I understand, blind people have a problem with this as well. They can develop a problem with this as well. Yes, they do. Depending on the nature of the blindness, if it's at the level of the retina, there are cells inside of your eye whose principal job is not to construct vision.

49:06They have no interest in vision. All they simply are doing, they are light meters. And they are there to tell your brain, do you have light or do you have dark? Right. And if you lose those cells, your brain is never able to receive that signal of light. And you can start to have difficulties in your circadian rhythm. But to come back to Anna's question with night shift work. Firstly, I love the fact that Anna loves her work and that she wants a longer life. That's exactly the right instinct, of course. But I should probably be honest and trying to be practical at the same time. The hard truth is that rotating night shifts are tough on your circadian biology.

49:49And there are health consequences that have been associated with it. In fact, the World Health Organization some years ago, and they repeated this mandate just recently, they classified any form of nighttime shift work as a probable carcinogen because of the relationship between a disruption of your sleep, wake rhythms, and the relationship with cancer. And that's not meant to frighten you. It's meant just for us to earn the respect for the risk that you take by giving us the opportunity that if I have an appendicitis at 3 a.m. in the morning, there's someone there to save my life, which is unbelievably incredible.

50:28So firstly, thank you for that. But because your body runs on that natural 24-hour sort of cycle, when you fight your biology, you typically lose. and the way you know you've lost is disease and sickness yeah and so what to do what what can we sort of help here there's probably a few things the first i would say is that direction matters that if you are a shift worker and you have to do these rotating shifts try to shift clockwise with the clock so so do sort of a morning shift then an evening shift then a night shift then a morning shift if you get the it now some people don't have this flexibility but if you are someone who is creating these shifts or you have the optionality, try to shift forward in time and your biology is much harder to go in reverse.

51:19The second thing I would say to Anna is be careful of your drive home. That is the most dangerous part of your shift. And so if you can try and get a lift home, try and take public service, whatever it is, just try to be careful because a tired driver is based on the evidence, not dissimilar to a drunk driver. If you look at some of the data, the next thing I would say is try to defend your daytime with as much nighttime-ness signaling as possible. What do I mean? When you get home, make sure that your home is blackout curtains. You are ensconced in darkness, get the room cold because your body is expecting a temperature drop at night, eye mask, earplugs, and then try to take a little bit of melatonin about two to three hours before you expect to try to sleep during the day.

52:15You can also take a hot bath or a shower about an hour before bed. Why would you do that? Your brain and your body need to drop their core temperature by about one degree Celsius, two to three degrees Fahrenheit to fall asleep and stay asleep. It's the reason that you'll always find it easier to fall asleep in a room that's too cold than too hot because too cold it's the right temperature direction so why the hot bath or shower you think well i get out the bath and i'm all kind of toasty and that's why i sleep well it's the opposite that when you get into the hot bath or shower it draws all of the blood from that's trapped at the core of your body out to the surface it's almost like a snake charmer that you're drawing the hot blood out and when you get out of the bath all of the heat that's trapped in the body is radiated out because it's been lifted to the surface and your core body temperature actually plummets and that can help you because your body temperature you're tricking your body into thinking that you're you're it's nighttime it's nighttime yeah exactly that's very so i would say those are the things that you could try to do again just be careful of the drive home and then make your home when you get home like a cave cold dark quiet so matt real quick i just want to say because I think this is important from my own personal experience and maybe you can speak to it.

53:29I had a job where I had to get up at three o 'clock in the morning and I was still doing comedy at night. So I wasn't getting any sleep, okay? And I've been very open about the mental illness issues that I have. And all I can say is what you just talked about, anyone who suffers from mental illness of any kind, whether it's depression, bipolarism or anything along those lines. The sleep is so very important. And I went into a very dark period because I just wasn't getting sleep. And so the sleep health that you just described is really important for those of you who suffer from mental health issues.

54:16I want to salute that flag every single time you hoist it because sleep is, it's not part of the equation. It is the foundation on which your mental health sits. And there's almost, you can't clean eat your way out of insufficient sleep. You can't exercise your way out of insufficient sleep and trying to protect your sleep when you know you are vulnerable from a mental health context, or if you know someone who is suffering from mental health conditions, try to see if you can help stabilize someone's sleep. That means the circadian rhythm, giving them bright, lovely, some exposure to daylight in the first 60 minutes when they wake up.

55:02That actually sets like an hourglass turned over, a timer to instigate the release of a healthy dose of melatonin at night that can stabilize your sleep rhythms. And then when it's nighttime, digital detox, try to turn down almost all of the lights in the home, try to disengage the mind but i cannot just emphasize more than what you just said it is such an essential ingredient and when it goes away goodness can we become vulnerable and we become vulnerable very quickly based on the studies that we've done digital detox means

55:34Neil deGrasse Tyson:put away the phone and the tablet that's right i'd rather die

55:42I'm sorry, I was channeling my children. Time for a couple more. Gary, what do you have? John Geffen from Wynwood PA. I have been fascinated by the recent discussions of consciousness in StarTalk. So what does our understanding of non-REM sleep tell us about consciousness? Can consciousness really turn off during sleep, or might it continue throughout and just be blocked from our memory when we wake oh what a good question so in other words if you're asleep and you're not an rem what is your state of consciousness from everything that we can tell you are absent consciousness meaning that if i wake you up from deep non-rem sleep and i say what was going through your mind nothing nothing will nothing come to mind wake you up out of light non-rem sleep often you can have these sort of little mini dreams of lite dreaming as it were but when you go into REM sleep that's full-blown dreaming but there was a there was a beautiful kind of twist in that story which is well is it just simply that my memory is blocked now that actually is the case for most of us with REM sleep dreaming because as I mentioned earlier you have all of these florid experiences and you typically forget a lot of your dreams but I don't know if that's true or not yes and we think we understand why it is that dreams dissolve so quickly when you wake up it comes back to the prefrontal cortex because it's your prefrontal cortex that is capturing all of the information and then sending it to another part of your brain called the hippocampus which sits on the either left and right side of your brain and the hippocampus packages that those experiences as memories, but it needs the prefrontal cortex as a spotlight to direct those memories into the packets.

57:32And if you don't have a prefrontal cortex that's active, which you don't when you're dreaming, it's very difficult, we believe, to package and send those memories into storage. I've got a wacky theory that we don't forget our dreams. In fact, I would argue we may remember every single one of our dreams. And it's the difference between what I call accessibility versus availability. How many times have you had that experience where you woke up and you think, I was dreaming, I know I was dreaming. And the harder you try, the further you push it away and you just give up. And then two days later, you get into your car and you see maybe a pack of chewing gum.

58:13And it's a cue that all of a sudden unlocks that full dream memory from several days ago. What that tells me is that your brain is storing the memory, but what you've lost at the moment of waking up is the ip address for that memory so the memory has been stored and is available it's just that you've lost the connection for its accessibility so availability accessibility which means that if that's true that we can have these spontaneous cued recollections of dreams days later what if we store all of our dreams and we know for a fact that there's a lot of information that sits below the radar of consciousness that is changing our human behavior and our decisions and our actions.

59:00What that leads to is a bit of a mind-bending possibility that all of our dreams are stored throughout our life and those dreams are constantly shaping and changing the decisions and the beliefs and the thoughts that we have in our waking life. And we're completely unaware of it. Wow. Yes. That, first of all, that's just nuts. I don't mean like nuts as in like you're a quack. I mean, it's nuts as in to think about - How many people have said that, but - But no, I'm saying it's nuts to think about the implications of what you just said, you know. But it definitely works for creativity. I can speak to that personally because I have had dreams that I wake up and I'm like, I can't remember.

59:49and I know that they're like, I wrote a joke or something happened, but then I'll be sitting down doing something completely unrelated at a different time and that dream will pop in my head and I'm like, oh man, there it is. And I'm like, oh, that's the joke. And then I'll tell the joke and people will be like, you suck. No, I'm joking. I'm joking. No, yeah, but it's useful. It's useful is what I'm saying. Yeah, and isn't that, I mean, And there's a couple of experiments that I think I could design to try to prove that that's the case. And then we could get into the whole world of, okay, if you can understand where memories are stored during dreaming, could you start to manipulate those memories during the dream state itself?

1:00:34Can you alter memories or can you selectively decide which memories that your sleeping brain brings up and remembers and which it wants to selectively forget. We're starting to get to the stage now where we've developed experimental tools where almost like a playlist, I can select what it is from your waking day that you decide to remember and what you lose. The even deeper implication of what you just said is if that's the case, then maybe all memories are stored that way. And if that is so, and you're able to manipulate it, Alzheimer's patients, you would be able to find a way to raise their memories like the way we dust for fingerprints or something.

1:01:20You'd be able to raise those memories and they wouldn't suffer. They might still have Alzheimer's, but they'll still be able to access the memories. And the question is, is Alzheimer's a condition of availability, but impaired accessibility? And the sad part is that because of the neural degeneration that happens, particularly in the memory centers, we think that in fact, those memories are no longer available at all. Oh. So it's like a damaged, it's like a corrupted file. It's like a corrupted file at that point. The file's there, but it's inaccessible. The file's there, but you can't get to it.

1:01:54Oh, that's a shame. Good idea though. Yeah, tragic. I tried.

1:01:58Neil deGrasse Tyson:I tried to help you people. Can we take one more question, but we gotta do it like in 30 seconds. Rapid fire. Yup, come on Walker. Okay, Brian Edair. I was wondering how the astronauts on Artemis 2 sleep on the shuttle. Do they have any special procedures? And would we expect them to have different types of dreams or nightmares based on being in zero gravity in space? Thank you so much. Okay, they weren't on the shuttle, just to clarify that. Sophie Adair is aged 11. She's given a pass. Okay, okay. I got you. By the way, great question, Sophie. It's a great question. I think it's one of the best questions of the night.

1:02:39How do astronauts sleep up there? I would say, honestly, with some difficulty and a lot of Velcro, because when you're on the space station, astronauts will actually climb into a sleeping bag that is strapped on the wall. And the reason is because so they don't drift around and start bumping into things. And there is no up or down. And as a result, you actually, because of that zero gravity, you don't need a pillow pressed against your head. so astronauts will actually describe sleeping almost like this sort of gentle floating experience and some of them love it some of them never get used to it but the real troublemaker is actually not the gravity or lack thereof it's the sun because circling the earth the crew will actually see a sunrise and a sunset roughly every 90 minutes so they will see 16 sunrises and sunsets every single day.

1:03:35Now, as we spoke about with your circadian rhythm, your brain carries this internal clock and it's carried it for three and a half million years. And it's been set to only one sunrise and one sunset every 24 hours. So it scrambles the brain is what you're saying. Your clock gets shouted at 16 times a day in a completely unexpected manner. So astronauts will typically black out the windows, they'll wear eye masks, and they will keep a very strict schedule that is sort of determined to make sure that they get timed light in accordance with when their biology is wanting it, and they will get timed darkness, together with a little dose of melatonin, to try to help convince their brains that it's nighttime when mission control says it is something different.

1:04:21Neil deGrasse Tyson:And of course, they only orbited Earth a few times before they did a translunar injection and headed to the moon. So then they're no longer orbiting Earth because now Earth is not blocking their view of the sun, putting them into nighttime. And so they still have to think about a rhythm because now they're just floating in space towards the moon. They don't get any sunrise or sunset. They'll get no sunrise or sunset. Yeah, well, I've got to say, though, that's probably better than 16. Like, I'd rather have no sun. Like, can you imagine somebody saying to you, like, let's take a romantic stroll on the beach and watch the sunset.

1:04:54Again? F that sunset. You know how many sunsets I've seen?

1:04:59Neil deGrasse Tyson:I don't give a damn about no sunset. So newsflash, Christina Koch, one of the Artemis two astronauts, came back and said she had some of the best sleep she ever had in her life. Oh. I'm just saying. Well, that's kind of sad because you're not going back to space to sleep. Like, you're never going to find that here on Earth. Well, here's a funny one. So Tempur-Pedic, when they first came on the scene, they marketed themselves as being the material under the seat of astronauts. Right. Okay, that go into space. And you say, wow, I want to sleep on what the astronauts sleep on. Except when they're in zero G, there is no pressure on the phone.

1:05:40Neil deGrasse Tyson:On the phone. There's no memory for the memory phone to remember. Exactly. It was a little spurious there as I saw. Well, I hate to tell you, I have a Tempur-Pedic mattress at home. You do? I do. Yeah, so in space, there's no bed sores. There's no, half the reason why you turn at night is to change the pressure on your body. Pressure on your body. That's correct. If you're in zero G. Yeah, there is no pressure anywhere. You're just floating. Yeah. I think there was a mention of, you know, what about dreams and how would that change? We don't have actually good data on this, but my scientific hunch is that your dreams are probably not altered by anything to do with gravity.

1:06:22It's the emotion of being, you know, a tiny crew in a tin can, thousands and thousands and thousands of miles from everyone that you love looking back at the whole earth through a window. I'd wager that probably shows up somewhere in their dreams. And I would love to see the emotional kind of arc of acceptance of the the monumental nature of what I'm experiencing in this moment, what this means to me. And then the integration of all of that. Could you imagine what an absolute mind twisting. I like to imagine that they all wake up and go, I had a dream. I was falling. Really? I had that same dream.

1:07:02They all had the dream that they were falling.

1:07:04Neil deGrasse Tyson:Like, yeah, guess why? All right. Matt, we got to call it quits there. It's been a delight to have you back on. Absolute pleasure. Thank you. Clearly our fan base, our Patreon fan base agrees with me that you've taken us to places we don't typically go. And Special Edition is all about the human condition. Yeah. And so thanks for helping us gain some insight there. It was lovely to chat, gents. As always, I suspect I will have some very interesting dreams tonight as a consequence of this. And we're going to find you on your podcast, eponymously named, do I say that right? That's correct. Matt Walker Podcast.

1:07:46Neil deGrasse Tyson:I presume you talk about sleep topics. I do indeed. And is there a website or a Twitter handle we can find you on? You can just go to sleepdiplomat.com. And if you want to find me on X, I am also there, sleepdiplomat. and on Instagram, I am Dr. Matt Walker, D-R-M-A-T-T-W-A-L-K-E-R. All right, we'll find you there. All right, dude. And any books you're writing? My previous book, Why We Sleep, has been out for now some time, and I will simply say that there is a second one that apparently should be being written at this time. Uh-oh. Oh dear. Uh-oh. Deadline. That one's gonna be called Why We Procrastinate.

1:08:34The tagline will be, torpor hibernation and what happens when you dream about going to Mars. Anyway, that, yeah, there is a second book soon to be arriving on shelves.

1:08:45Neil deGrasse Tyson:No great piece of writing is ever finished. It only comes due. Woo! Look at that. Give me that T-shirt, please. All right, Chuck. Always a pleasure. Always. Yeah, Ray. Hey, Neil. In the house. Neil deGrasse Tyson in another edition of StarTalk Special Edition. This one on sleep. Thanks for joining us. Until next time, keep looking up.

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