Why do we sleep and dream? (featuring Dr. Gina Poe)

00:00:06
Speaker 1: Sleep.

00:00:08
Speaker 2: We spend around a third of our entire lives doing it, completely oblivious to the world around us. Some animals, like cheetahs, toads, and squirrels, spend at least half of their lives asleep.

00:00:21
Speaker 1: It's kind of baffling when you think about it.

00:00:23
Speaker 2: Time spent sleeping is time that can't be spent doing things like searching for food, and if you're a wild animal, time spent sleeping is time when you're less able to detect a predator in the area.

00:00:34
Speaker 1: So why do we sleep?

00:00:36
Speaker 2: It turns out this activity that swallows up so much of our short time on this planet is really hard to study, but scientists have made some headway on this question of why do we sleep? And today we're going to talk to doctor Gina Poe about why we sleep and chat with her about other fascinating questions like do mushrooms sleep, does an octopus dream? And does all all of our brains sleep at the same time or do some parts fall asleep before the others?

00:01:05
Speaker 1: Welcome to Daniel and Kelly's Sleepy Universe.

00:01:21
Speaker 2: Hi.

00:01:21
Speaker 3: I'm Daniel, I'm a particle physicist and I don't sleep particularly well.

00:01:26
Speaker 1: Hi I'm Kelly Wiersmith.

00:01:27
Speaker 2: I study parasites and space, and I'm not gonna blame it on the parasites. But I don't sleep very well either, But I love sleep, Like when eight to thirty comes around every night, it is like the only thing on my mind. Zach is like, it's only a thirty Are you going to pull an all niner and stay up past nine? And I'm like, I'm gonna do everything I can and be in bed by the time nine o'clock rolls around.

00:01:47
Speaker 3: Young people don't appreciate how nice it is to be home in the evening and have no plans, I.

00:01:52
Speaker 2: Know, and have a comfy bed. Ah the blessing that is a comfy bed. It's one of my favorite things.

00:01:58
Speaker 4: It is.

00:01:59
Speaker 3: Yes, when sleep well, it is definitely one of the best things in the world. But when it's fraught, man, I've had nights that lasted a thousand years.

00:02:05
Speaker 1: Oh my gosh. Yeah, no, me too.

00:02:07
Speaker 2: We went camping once and it was a little bit rainy and wait, so we weren't really camping. My daughter and I were sleeping on the trampoline and it started to rain and then it got really cold, and then my back hurt. But I didn't want to ruin the night for her, and so I tried to make it work. And then at like five am, I was like EIGHTA, we're moving inside.

00:02:26
Speaker 1: I needed a nap. This is miserable.

00:02:28
Speaker 3: Well, it's amazing to me that sleep is something we just cannot do with that that we have to accomplish every single day, and also that it's something you can't really try to do. It's like something you have to try to not do, you know though, Like the harder you work at sleeping, the more you get worked up about it, and the harder it is too sleep. It's incredible. It seems so fragile. It's incredible that it ever works. I don't know.

00:02:50
Speaker 2: Yes, I think you and I are making clear that we don't have a very good relationship with sleep at all.

00:02:54
Speaker 1: But I wake up a million times in the middle of the night, and it's a.

00:02:57
Speaker 3: Thing, and it makes me wonder, like why we evolved this, why it's such an important part of our life cycle? If it's yet so fraud and so fragile, right, it seems like kind of a bad idea.

00:03:07
Speaker 2: I mean, I think it's possible that you and I are just broken in a particular way. And that this problem with sleep is not present for everyone. I mean, my kids conk out and they are out and it's fine for them.

00:03:18
Speaker 3: But that's also an age depending thing, right. A lot of kids have no problem with sleep, sleep all night, sleep anywhere, all the time. But then as you get older sometimes it gets harder to make it work.

00:03:27
Speaker 1: I agree.

00:03:28
Speaker 2: But so today's episode, we're talking to a sleep experts and we forgot to ask her about tips for how to solve our sleeping problems. She didn't solve our sleep problems, yes, but a guest wanted to know about dreams, why we dream, interpretations of dreams, et cetera. So, what is the weirdest dream you've ever had?

00:03:45
Speaker 1: Daniel?

00:03:45
Speaker 2: And let's keep it short, because I think notoriously people don't want to hear about dreams that other people have had. So real, quick, weirdest dream you've had?

00:03:53
Speaker 3: Well, as you know, I think a lot about aliens, and so lott of my weird dreams have aliens in them, and they're pretty weird and sometimes they eat me or my children, and sometimes it's my fault. Oh no, And so yeah, those are pretty weird dreams.

00:04:07
Speaker 2: There are so many insights about you wrapped up in that story. For me, it was my mom and I teamed up with the Berenstein Bears. We were a crime fighting organization and a murderer was on the loose and the murderer killed me because my mom, you know, went off down a hallway and we split up, which classically you should never do, and the Berenstein Bears had gone another way and anyway, big mistake. Yeah, But all right, So I don't know that there's much you can extract about me out of that dream in particular, but we are going to talk to an expert on sleep and dreams, doctor Gina Poe, and she's going to answer all of our questions about sleep and dreams.

00:04:44
Speaker 3: And she's going to blow your mind about what it means to sleep across the animal world.

00:04:48
Speaker 2: And so let's start by listening to the question from our listener that got this whole interview started.

00:04:54
Speaker 4: Hi, Daniel and Kelly. This is Carrie from the Pacific Northwest, and I was wondering if you can do show on dreams, why we dream, what part of our brain is being used when we dream, and just everything about dreams.

00:05:09
Speaker 3: Thank you, thank you Kerre for that wonderful question, and all of you out there listening, if you haven't already fallen asleep to this podcast, you are welcome to send us your questions about the universe. We will try to answer them, and we will sometimes rope in a world class expert to give you answers.

00:05:25
Speaker 2: And let's bring that world class expert on now. On today's show, we have doctor Gina Poe. She's the Eleanor Leslie Professor of Innovative Brain Research at UCLA. In addition to research, she directs three university programs aimed at supporting undergraduates who are underrepresented in STEM fields. She's done so many incredible things. I'm just going to cherry pick a few. Gina and her colleagues sent four rats to space as part of NASA's Neurolab mission to study how brains map the three D world in weightlessness where you don't really know what side is up. And she's well known for her discovery that's is important not just for remembering things, but also for forgetting things. Her lab at UCLA focuses on sleep and memory, which are the topics we're going to be chatting about today. Welcome to the show, doctor Poe.

00:06:11
Speaker 5: Thank you so much. It's great to be here.

00:06:13
Speaker 1: We're super excited, Gina.

00:06:15
Speaker 3: I have a first question, which is sort of goofy, which is what do you call a rat you send into space? Is it a ratronaut?

00:06:21
Speaker 5: Yes? Actually great?

00:06:24
Speaker 3: And do they have to undergo like a rigorous selection process you know where they like run on treadmills for hours?

00:06:30
Speaker 5: Actually yes, yes, we started with forty rats and ended up before so and.

00:06:35
Speaker 3: Those were the four that had the rat stuff.

00:06:37
Speaker 5: Yeah, the rat stuff nice, amazing great.

00:06:43
Speaker 2: Okay, so let's start big with why do we think we sleep? And how well do we understand the answer to this question.

00:06:50
Speaker 5: There are lots of answers to that question. I think that there probably is one essential reason why we sleep, but we don't know the answer to that question. But we do know a lot of essential things that happen during sleep with which we can't do without. For example, energy metabolism goes way up when we're asleep. What I mean by that is not actually metabolism, I mean restoring energy stores to our entire body. Our mitochondria wake up when we go to sleep, and they are doing their job much much faster and restoring atp to all of our cells. So that's just one essential function of probably twenty that we know of.

00:07:35
Speaker 3: Why do we have to be asleep for mitochondria to do that? Why can't they just do it while we're doing our thing?

00:07:41
Speaker 5: I don't know. That's a good question. That's actually a fairly new discovery.

00:07:47
Speaker 1: And is that happening in all of our cells or just our brain cells.

00:07:51
Speaker 5: It's been discovered in fruit flies brain cells. Okay, so that's a good question. I imagine it's going on everywhere. But we know that the longer we're awake, the more free adentiicine builds up in our brain, and that free adenticine is a signal for sleepiness. And as soon as we go to sleep within thirty minutes, that freodentisine has been repackaged by mitochondria into ATP. So the freodentisine levels go way down when we're asleep in the first twenty minutes, which is probably why power naps are called power naps.

00:08:28
Speaker 2: I do love me a power nap, me too. And now I feel way more justified in that you said.

00:08:33
Speaker 3: There are like twenty different things that happened when we sleep. One of them is we're restoring energy stores. What are some of the other ones.

00:08:39
Speaker 5: Okay, so well, we know that we consolidate memories when we're asleep, that's my field of research, and that without sleep, we don't put them away long term and our memory stories. Of course, memory is really important for adaptation to our environment, finding where our home is, et cetera. And so that would you can imagine that would be important for life itself. It doesn't seem like all animals should have to learn things, but in fact, every time we've tried to teach any animal something, they've been able to learn it. Even mushrooms can learn it. And there's some interesting study by vlad Vyazovsky that shows that even mushrooms need sleep.

00:09:20
Speaker 1: Well, what does sleep look like in a mushroom?

00:09:22
Speaker 5: Like, what are they missing exactly? I don't know, you'll have to ask Glad, but it came up with a very convincing argument that mushrooms do sleep.

00:09:30
Speaker 2: Oh wow, okay, so then that I'm going to jump ahead then to another question that I had before, we go back to purposes of sleep. Okay, so I would not have guessed you were going to tell us that mushroom sleep. That's an amazing surprise. I'm going to try sneaking up on some of the mushrooms in my yard.

00:09:45
Speaker 3: Now, Kelly, they're busy consolidating their memories of the day. You're going to ruin it for them.

00:09:50
Speaker 1: I'm sorry.

00:09:51
Speaker 2: I know all the tricks they were trying to learn. So, so, what organisms sleep or like? Maybe it sounds like the better question is what organists don't sleep, given that even mushrooms sleep, Like, do bacteria sleep?

00:10:04
Speaker 5: That is a good question. They definitely have a circadian rhythm, so they have a time when they're not actively pulsing or whatever and times when they are. So yeah, it's a good question. I don't know the answer to that one, and it would be difficult probably to tell in bacteria except for that sort of change in activity. I guess it would be the only way you could tell. Certainly, our gut bacteria are doing different things at night versus the day, and their rhythm gets messed up when we have jet lag, for example.

00:10:37
Speaker 3: And in all these creatures that sleep, is it all linked to the same day night cycle.

00:10:42
Speaker 5: Yes, except that, for example, there are rats and mice who sleep during the day. So there are some things that are flipped. The switch is flipped. But even for rats and mice, Melatonin, which is the hormone of darkness, is higher during the night when they're awake and active.

00:11:00
Speaker 3: So I have a question based on a tiny amount of anecdotal data. When I go to sleep, my dog is in one place, and if I ever wake up in the middle of the night, he's sleeping in another place, And in the morning he's in a third place because he has like nineteen different places he likes to sleep in our house. Okay, so my question to you is what is my dog doing all night? Does he just take naps and then move around? Is he, like, you know, up learning how to make souflets in the middle of the night. Like, why don't dogs sleep all the way through the night? What's going on in my house? Gina?

00:11:29
Speaker 5: Tell me dogs and cats predators actually sleep a lot more than prey species do. They sleep about sixteen hours a day in a nice home environment. So, yes, your dog is waking up more than you do, probably at night and maybe going to get some water or just checking out the house and finding a cooler place to sleep. But if you were to put a camera on your dog, your dog isn't roaming around and hunting like a cat. A cat is more crepuscular, so they have a lot of activity in the morning and in the evening, but they sleep a lot during the day, and they sleep a lot during the night as well. But dogs are a lot more diurnal like we are. So, yeah, your dog is pretty much rest assured, sleeping all night, just getting up once in a while when they're uncomfortable or they're done with the sleep cycle.

00:12:22
Speaker 3: I was kind of hoping he was writing like the great American novel in the middle.

00:12:26
Speaker 2: Yes, so my brain is a little bit stuck on the mushroom thing, and it's making me wonder how do we define sleep? Because you know, I thought maybe we would define it by like brain waves or things that you wouldn't be measuring in a mushroom. So let's let's step back even farther than how do we define sleep?

00:12:45
Speaker 5: Yeah, so there are animals we can't define sleep via brain waves because their brain isn't organized the same way ours is. In order to be able to see those brain waves, we have to have an alignment of neurons, because each neuron has you know, a t any little electrical signal, and when they're all aligned in the same orientation, you can see that electrical signal sums, and we can see it from a place as distant as the surface of your scalp. There are three layers of skin, four layers of skin actually between your actual brain cells and the electrode, plus bone and water. So you can imagine that that signal would be reduced the further distance you are away from your brain.

00:13:29
Speaker 3: So that's what brain waves are. Sorry to interrupt, I just I've always wondered brainwaves are measurement of the electrical field caused by firing neurons.

00:13:37
Speaker 5: Yes, exactly. They actually don't even have to fire. The membrane potential just has to depolarize or hyperpolarize so become more positive or negative.

00:13:48
Speaker 3: It's amazing there's any signal in there at all. Yeah, why are the neurons oriented physically in the same way so that they can constructively build a signal? That's incredible.

00:13:58
Speaker 5: Yet why is a great question. I don't know the answer to that, but they are the biggest neurons in our brain. Are these things in our cortex called pyramidal cells, which are shaped like pyramids, which is why they're called parametal cells, And they are just oriented on the folds of our brain facing outward, and there are tufts of antenna at every pole of the pyramid, and the ones at the base are called baseler dendrites, and the ones at the top are called aprical dendrites. And the apical dendrites are the ones that reach all the way to the very surface of our brain, and they are the ones that get communication from other areas of our cortex. So when we're thinking thoughts, that's all come again our apical dendrites. When we're feeling feelings that are coming from the outside, like our sensations, they come in at the baselin drites, and the ones that are closest to the apical dendrites, not the distant ones, So they're just all aligned like that in our stray of our cortex, or as you've probably seen them, they're folded. So it's only at the top of those striations that you can get the electrodes and see what's going on. So we can with our electrical EEG electrodes, you can only see a small percentage of what's going on in our brains, and only what's at the surface because as the distance increases, the signal decreases. Exponentially.

00:15:27
Speaker 2: Yeah, and so we use that information to define sleep in organisms where that works. Yes, is that otherwise what kinds of things would we be looking for in organisms that have a more like distributed nervous system where it's harder to do that kind of stuff.

00:15:41
Speaker 5: Yeah, So organisms like the octopus, it has more ganglia, like, it doesn't have a cortex like we have. And so the neurons are there, of course they're there. They are all over their legs and central brain area, but they're organized in very kind of more random fashion. So even though they're just as electrically active as ours our, the electricity you know, is going in different directions and so it doesn't summate, so we can't really see them with electrodes. So instead we need behavioral measures. And so animals usually have a typical sleeping position or positions. Even the sea elegans worm has this typical sleeping position and they sleep like it's called a shepherd's hook. It looks kind of like a question mark. That's their sleeping position. It's kind of cute. Yeah, it's really cute. And then they're all these animals are less sensitive to what's coming in from the outside, so I wouldn't suggest this, but you can tap on your fish tank at night and the fish won't respond the same way that they respond during the day. During the day they'll respond right away and swim around, but at night they'll just sit there and maybe a few seconds later they'll sort of arouse and respond. So they're less responsive to the outside world. But it is a reversible state. To determine and distinguish it from coma, it's homeostatically regulated, which means that all animals that you deprive of sleep will try and get more sleep the next opportunity they have. So there is a great study of jellyfish, which don't have a central nervous system either at cal Tech that showed that these cassiopeia, which are these upside down jellyfish sleep at night like we would expect, and what they do is they find the bottom of the tank or whatever they find something to rest on to sleep, and then they just start pulsing more slowly. And then if you wake them up a bunch of times at night by giving them a jet of water or something to deserve them from their sleeping position, they will wake up, pulse faster, try and find the bottom again and go right back to sleep. And if you do that all night long, the next day they'll map a lot more. WHOA, I know.

00:18:01
Speaker 3: Do you need some sort of ethics review to torture these jellyfish this way all night long?

00:18:05
Speaker 5: You know?

00:18:06
Speaker 3: Is that a yes or no?

00:18:08
Speaker 5: I wasn't sure, no, but thankfully not.

00:18:10
Speaker 2: How many people are doing this so if they had vertebrae, you would have to yeah, right, exactly exactly.

00:18:17
Speaker 3: Oh, I see, So rats have ethical protection, but jellyfish you can torture as much as you like all their larve right right.

00:18:23
Speaker 2: Wow, we would not call it torture, Daniel, the physicists.

00:18:28
Speaker 3: I'm trying to speak here on behalf of the jellyfish. This sounds like torture to me. You come in my room and wake me up ten times a midd of the night, I'm not going to be very pleasant the next day. I'm going to do more than just nap, I'll tell you that much.

00:18:39
Speaker 5: Yeah, you can't get their consent with people. You know, you get people volunteering for these kinds of studies all the time, and yeah it's not great, but they you know, they like contributing to our knowledge of what sleep is about and seeing what their own sleeper is like. We can't give the same feedback to jellyfish, but we do allow them to sleep the next day nop as much as you want. You can also give them caffeine. It works the same way. It keeps them up and makes them more active. Interestingly, in that study of jellyfish sleep, they found that they pulse more slowly at night. If you wake them up, they pulse faster. But in a I think it was figure two of that paper they don't even describe. There are periods of time when they're not pulsing at all, which is, you know, like not breathing essentially for twenty or thirty seconds at a time, and that could mirror the second stage of sleep, which I'm sure we're going to get into later, which is our dream stage at sleep, and in order to not act out our active dreams, we actively inhibit all of our muscles, not our breathing muscles, thankfully, not our heart muscles, thankfully, but all of our anti gravity muscles, so that we are acting out our dreams. And it seems like jellyfish have the same kind of called atonia no muscle tone, that we have, and they do it periodically throughout the night. The authors of that paper didn't describe a second state of sleep for jellyfish because I guess they just wanted to avoid controversy, or maybe they had it in the original draft and reviewers just said you need more evidence. But also spiders and octopus they all have this second stage of sleep. And when spiders have atonia, what do you imagine that they look like?

00:20:26
Speaker 1: Do they look like the dead dried up?

00:20:28
Speaker 5: Yes? Really they do.

00:20:30
Speaker 2: Wait, so like if I find a black widow in my garage and it's all dried up, it might just be sleeping and not dad.

00:20:35
Speaker 5: It might just be sleeping.

00:20:36
Speaker 2: Oh interesting, that's a little scary.

00:20:40
Speaker 5: Okay, it might be in that RAM sleep. Now. We call it ram sleep in humans because we have rapid eye movements and that corresponds with our dreaming. Actually, spiders also have rapid eye movements during that state.

00:20:53
Speaker 1: And do all of their eyes move?

00:20:54
Speaker 5: Yeah, their eyes move. You can only see it in very young spiders where they don't have the dark yet coloring, so you can see through their carapace and see their eyes moving and also coolly. When we're in rams sleep, our eyes don't always move conjointly like if they do when we're awake, so we could have one eye moving this way and it's just not for some reason. Maybe our brainstem areas that are helping our eyes track the world are not coordinated when we're in reun sleep. And that's true at spiders as well. So during wakefulness their eyes move together in a ram sleep state, which we can call rams sleep, and spiders, because their eyes are also rapidly moving, their eyes don't move conjointly. In cockroaches they have rapid intennel movement sleep, so they're antenna well you know, hu jiggle.

00:21:44
Speaker 3: That almost sounds cute wow.

00:21:46
Speaker 5: And bees as well. Bees will have rapid intennel movements sleep.

00:21:49
Speaker 2: And do we have evidence for these animals that they're also consolidating memories while they're sleeping or do we think they're doing something different.

00:21:57
Speaker 5: I don't think they're doing something different, for example, in the act, so they don't. Actually I don't know if anybody's looked at the eye movements of octopuses. I think probably they have, and they probably do move as I recall, But any case, what they do, one of the ways you can tell they're in rem sleep is that they flash their colors, so their camouflage gets flashy, like, for example, a dog twitching its pause.

00:22:23
Speaker 3: That sounds like science fiction. That's crazy, Yeah, I.

00:22:26
Speaker 5: Know it is crazy. So they have a sleeping position too. They don't like to sleep except if they're safe, like crawled into a hole in a rock or something like that, because they also are prey for other sea animals, so they try and get to a safe place and a place where when they're flashing they can't be seen.

00:22:45
Speaker 2: Yeah, i'd want to hide that color party, yeah, for sure from predators.

00:22:48
Speaker 5: Yeah, exactly.

00:22:49
Speaker 3: So this has been a fascinating tour of sleep across the animal kingdom and the fungal kingdom and all sorts of crazy stuff. But it sounds to me like the fundamental answer is that we don't really know what sleep is. Is we have this thing in humans we call sleep, and we can find correlated activities and other creatures that are not the same because they have different brains and different bodies, but we still call them sleep. What is the thing we can say unifies sleep across all of these folks. How do we know we're not just projecting our human experience onto mushrooms and black widows?

00:23:21
Speaker 5: Right? Well, I think the less responsive to the environment. You're not reproducing, you're not ingesting food. Actually in ungulates, let's go back to ungulates for a second. I think that was studied in I think it was camels ruminants, not ungulates ruminants. So they were thought to sleep a lot less because they're actively chewing a lot. But in fact they can chew while they're asleep. So it is a really good question.

00:23:50
Speaker 2: WHOA, I'm lucky I can't chew while I'm asleep. I know i'd get myself in trouble. I do love food.

00:23:57
Speaker 5: Yeah, well it's kind of like tea grinding, I guess in humans, but you know they have something to chew on their cud. So that's a really good question. And I think that it's still controversial, Daniel, because if you define it behaviorally, you would say someone who's sleepwalking isn't sleeping because they're walking. But in fact we know because we can measure eeg that they are asleep while they're sleepwalking. So it is tricky. But we do also know that the brain at least is doing something wildly different, wildly different than when we're awake. We are not processing the outside world in the slow wave state of sleep, which is one of the two states. Our brain activity electrically is periodically active and inactive, and the frequency is about one hurts. So we have this blip of activity and then a lot of silence, and this silence is something you never see during wakefulness, and then a little blip of activity and then a lot of silence, And so consciousness is probably completely severed during those periods of time when the brain is completely inactive, and those little blips of activity one hundred milliseconds long or so are probably too short to be called consciousness and certainly too short to write memories into any long term stores. So that's probably why we consider ourselves unconscious. During rem sleep, it's an entirely different state. The brain is super active, but that activity is all internally focused, so not focused on what the outside world is, but this inside reality. And that's probably the case of octopuses when they're flashing their camouflage.

00:25:43
Speaker 3: All right, So that's been a fascinating discussion of meditative mushrooms and napping black widows. When we get back, let's talk more about what's happening while we sleep and what it means to dream.

00:26:13
Speaker 2: All right, So I remember hearing that something like dolphins and birds sleep with half of their brain at a time, which sounds great because then you can be awake. But anyway, so my question is is that actually happening, and what does that look like and what are the like bonuses or drawbacks of that technique.

00:26:32
Speaker 5: Right, Well, if you're a dolphin, the bonuses that you can continue to breathe all night long while you're sleeping solid, so the half of your brain that's awake keeps the dolphins swimming at the surface and able to breathe all night long. They switch sides, so one half of the brain is sleeping for a while and then the other half of the brain sleeps for the rest of the time and just switch back and forth. Interestingly that the one neurochemical that seems to be changing when the consciousness side changes is a seat of coline, which is a neurotransmitter that goes all over the brain from one area of the brain stem and it's considered to be the searchlight of consciousness. So when you're thinking about walking upstairs, a seedal coline goes to the motor areas that are responsible for your feet walking upstairs, and when you're thinking about doing math, A set of coline goes to the math areas of your brain and away from the walking upstairs. If you're doing walking upstairs and doing math at the same time, of course, the seat of colon is in both places.

00:27:36
Speaker 2: And you're probably gonna fall fall anyway.

00:27:40
Speaker 5: So for dolphins fur seals that are out hunting for long periods of time and not accessing land for several weeks, they can also sleep un a hemispherically. Whales sleep, you know, hemispherically. And it's true, the side that's a sleep that doesn't have these heatal cooline has the big slow waves of unconsciousness, and the side that's awake looks like, you know, awake, and the eye is open on that side and all of that. So actually, so we control our brains. This is a little confusing. Our left side of our brain controls the right side of our bodies. So if the left side of the brain is awake, the right eye is open and watching the world around them, and vice versa. But so rim sleep rapid I'm of sleep. The one that I talked about where you have atonia seems to occur only very briefly in these animals that are uni hemispherically sleeping, So there's something different about rimsleep that really requires atonia, and maybe that's why it's only fifteen seconds long in the dolphin. And we haven't recorded the EEG the electrodecephalogram from dolphins or whales. It's a little more difficult. There's a lot of fat between, you know, to help them float between their skin and their brain, and no one has attempted it. But we do have another state of sleep in whales at least, and I don't know if it's been observed in dolphins. It would be interesting to see, but where they're not just floating at the surface and breathing and sleeping one hemisphere at a time, but they're actually below the surface instead of a horizontal position, in a vertical position either head down or head up. And usually what they do is they start with head down and then as the waves and tides move their atonic bodies, they eventually sort of go to the head up position. It's just they have a lot of fat in the head. That's the one that's the more neutral position, and they will do that for twenty minutes at a time, and that's where their body is completely also atonic, and then they swim to the surface and breathe and wake up and breathe again.

00:29:47
Speaker 3: But I'm not sure I follow the basic idea of why some animals do this and some don't. You said, you know, dolphins need to keep swimming and breathing, but we also need to keep breathing while we're asleep. Why don't we do this as well.

00:30:00
Speaker 5: Right, because well, we can breathe while we're asleep without having to swim, you know, we just you know. So, Also, dolphins in Wales breathe voluntarily, so it actually requires a voluntary sort of waking brain to breathe, whereas we breathe involuntarily when we go unconscious. If we were holding our breath before we went unconscious, we will start breathing again.

00:30:27
Speaker 3: And whales and dolphins have ancestors that were land animals, right, which probably slept more like us. How do you think that evolution happened? How do you evolve this kind of thing?

00:30:36
Speaker 5: Right? I don't know. It's incredible, you know the differences between species. It's really a beautiful and amazing thing.

00:30:45
Speaker 2: So you mentioned that seals when they go off on long foraging trips can do uni hemispheric sleep? Do they alternate between un a hemispheric sleep and then everything? Yeah, like the whole brain going, oh wow, they can do both.

00:30:57
Speaker 5: Yeah, when they're on what land they do by you know, whole brain sleep.

00:31:01
Speaker 1: Wow.

00:31:01
Speaker 5: Yeah. And there's an elephant seal that isn't found to do in a hemispheric sleep, either on land or at sea, And so that was used to argue that maybe sleep isn't necessary because they would be out there foraging for a couple of weeks and they're not sleeping for those couple of weeks, and then they go back to land and they don't have homeostatic rebound like they had been sleep deprived for a couple of weeks. So it was thought that maybe these are animals that don't need to sleep, and maybe sleep isn't necessary or at least not always homeistatically regulated. But a few years ago someone at EC Santa Cruz outfitted these elephant seals with head caps so they could record from their brains while they're out there swimming, and they found that in fact, these head caps also had GPS. They found that they actually do sleep while they're out there foraging, and what they do is they take a deep breath, you know, lots of deep breath. They swim down, down, down to a depth beneath where sharks and killer whales would predate them and where if they fall asleep, and when they fall asleep, they start sinking instead of floating back up. And so what they do is they go into slow wave sleep, and they have these beautiful slow waves and they're just kind of coasting down as they go into slow wave sleep. And then when they go into rem sleep with the atonia, whatever body position they're in, if it's less than perfectly straight, which always is going to be less than perfectly straight, they'll start spiraling. You know. The fin that's down will make them spiral. So they will spiral down and down and down until they hit the ocean floor, or until about seven or eight minutes have passed and they start the oxygen need starts giving, making them decide that they need to wake up. And so they wake up and start swimming up to the surface. And they even while they're swim into the surface, they can hold their breath for all long time. So even when they're swimming to the surface, they could have little naps and then swim some more and yeah, it's super cool. So really, sleep has been found in every animal, and in every animal we look closely enough, seems to have these two stages of sleep, so both stages, and both stages are independently regulated, so both stages seem to be important.

00:33:25
Speaker 2: So wait, when one hemisphere is asleep, I assume that they're less good at doing like, they can't have social interactions or anything like that. They're just watching out for predators and trying to breathe.

00:33:34
Speaker 1: Is that right?

00:33:34
Speaker 5: Yes? Okay, I think so, Oh yeah, we don't see social behaviors which would take the whole body. I suppose they could flat one fin waving hey guys, taking a nap.

00:33:46
Speaker 3: Okay, And it makes sense to me that predators might sleep like they eat very calorie rich food, they don't need to move around their conserving energy. But pray. It seems to be like a huge disadvantage to ever go to sleep.

00:33:57
Speaker 5: That's right.

00:33:59
Speaker 3: Does that mean that it must be fundamentally important that you can't escape at this no evolutionary path away from it.

00:34:05
Speaker 5: I think that's what it means. Yes, So I would love to see sleep in the pond organism that can survive in space and radiation tartar grade tartar grades. I would love somebody to do with sleep in tartar grade study because because they survive so well despite all of these different assaults on them, they can they have amazing abilities to rebuild broken double stranded breaks in their DNA, which seems to be also one of the functions for sleep is to rebuild a double standard breaks in our DNA. So another animal that seems to be really good at repairing their DNA is the naked mole rat, which are really ugly or cute whatever you think.

00:34:58
Speaker 3: It's a personality test. Actually what the you like the naked mole rat?

00:35:02
Speaker 5: It is. So there are some studies done in San Diego and then some more studies done in Russia that of sleep in the naked mole rat, and they seem to sleep so much more than the rest of us. And the naked mole rat. And like other rats which live about two years, the naked mole rat can live thirty five years and when they die it's usually from accidents or injuries or something like that. So why do they live so much longer? Well, they have this superior ability to repair their double stranded breaks in DNA and their rim sleep is about fifty percent of their sleep, which as for us, it's about twenty five percent on a good day. For rats and mice it's more like twelve fifteen percent, but with naked mole rats it's fifty percent. And that's as much RAM sleep as we get as babies. So when we are, you know, learning so much from our environment. And actually I want to give you another factoid, which is learning requires double stranded breaks in our DNA, So every time we learn, we're breaking our DNA in order to do that. So, yes, I know why, I've never heard that before. Yeah, I don't know why. I don't know why. But sleep helps repair repair that and so so what are naked mole rats doing there? Babies are learning, of course a ton, right and there they have about fifty percent when they're born. So why are naked mole rats having so much rem all through their lives? Are they learning a lot? And there's also seem to be any evidence that they're so much smarter than anybody else.

00:36:46
Speaker 3: They're writing the great American novel.

00:36:47
Speaker 5: Of course, baby writing the American novel, but the only they can read.

00:36:53
Speaker 3: So you have a lot of questions about sleep and all these creatures any humans. Tell us a little bit about how we've learned these things, like experiments have you done? How do we know these things? Yeah, other than torturing jellyfish?

00:37:05
Speaker 5: Right, watching, right, watching? Just anybody can be a scientist, as you know, you just need to. You need to observe the world around you, ask questions and try and answer them by perturbing that that universe and seeing what happens. So we knowie, sleep is homiostatically regulated, even in ourselves because when we get less of it one night, we are sleepier the next day our drive to sleep is higher. But yes, there have been some key experiments throughout history. For example, the discovery of rapid I movement sleep was probably not the discovery of rapid I sleep at Rapit the first report of rappidive I haven't sleep that other people could read, and that was an observation made by at the University of Chicago by a research scientist who is actually the trainee of another research who was studying sleep. Yes, had EEG electrodes on people's brains, and this trainee said, hey, there seems to be this second state where eyes are moving and there's a bit of twitching and respiration changes, and the principal investigator the PI didn't believe it, you know, like, yeah, it's just a little bit of wakefulness or something else. Sleep is just one thing, and it's a we thought at that time it was a disconnect from the world and it was saving energy, which doesn't appear to be very true. Actually. So this trainee hooked up the sun of the PI and all night long. And this was a young kid, I think ten years old or younger, who has more rem sleep and is very thoroughly asleep. Kids for it's hard to disturb them. It's hard to wake them up out of sleep. Yeah, And so showed the record to the PA, this is your son. Look at these states, and the p I said, wait a minute, and Edison's sleep another night and watched them and you know, tried to poke them awake during their rem sleep. When he thought that one must have been a wakefulness, the sun was quite quite heavily asleep, and realized that, okay, there may be you know, maybe there's something to this, maybe there's a second state of sleep. So it's kind of you know, observations like this, someone saying, hey, this is weird. This doesn't follow my hypothesis is what I thought would happen, you know, and then pursuing that thing that's weird to its end to see what the answers are for humans.

00:39:40
Speaker 3: You're obviously limited in the experiments you can do. I want to ask you a weird question. Imagine that we're not limited.

00:39:47
Speaker 1: I think that's the only kind of question you asked me.

00:39:49
Speaker 3: I know this one's going to feel a little extra weird. Imagine you weren't limited by any ethical concerns and you only had scientific questions. What experiments would you do to learn more about sleep? You know, slicing brains open, torturing people, sticking things inside them. I don't know. What would you do just from a scientific point of view to learn about sleep? What experiments do you wish you could do?

00:40:11
Speaker 5: Yeah, I mean, if it weren't for the dangers involved, I would put electrodes in my own brain, a ton of them. I would put a thousand of them in my own brain. Because one of the things that we have discovered from people with electrodes in their brain, and they put electrodes in their brain because they want to find out where epilepsy is starting. So that they can go in and just take out that little section of brain which is generating epilepsy all over the brain. So when we have looked at twelve of those people who had electrodes already implanted in their brain, and we find that, in fact, sleep isn't a whole brain phenomenon one third of the time. For example, your hippocampus, which is involved in recording memories in the first place and then consolidating those memories to other parts of the brain. Here hip campus can be an entirely different sleep state than the cortex is, and it's about a third of the night that it's in an entirely different state. So, for example, you hip the campus can go into rapid eye movement sleep faster and better and longer than the cortext does. It can go to sleep actually the first place, sooner than the rest of the cortext does. So you could be in bed reading a book and about two minutes on average before you're actually fall asleep and the book hits your face or whatever it is, your hippa campus is already asleep. It's not going to remember those that last page that you read. You can also tell when you're falling asleep, you have to reread the same patches again and again. What was that? I don't know, you know, ugh, what was that? And that's called sleep onset amnesia. And we found in people that your hipp a campus can be asleep for twenty whole minutes before the rest of your rain is asleep. So don't have a critical conversation with your bed partner while they're trying to fall asleep, because it's possible they will not remember the conversation the next day at all.

00:42:05
Speaker 3: Oh my gosh, you have just inserted yourself in my marriage. I have a no important conversation after ten pm rule. There you go, which is controversial in my marriage.

00:42:18
Speaker 1: It seems reasonable.

00:42:19
Speaker 2: I'm almost always asleep by ten pm, so ZECH would not make much progress anyway.

00:42:24
Speaker 3: But now I have a scientific foundation for winning.

00:42:28
Speaker 5: You do you do?

00:42:29
Speaker 3: Thank you, Gina?

00:42:29
Speaker 4: Yes?

00:42:30
Speaker 1: And well science.

00:42:31
Speaker 5: Yes.

00:42:32
Speaker 2: All right, Let's hope we help some other marriages as well. And when we come back, we will talk about dreams. Okay, we're back and we are finally going to answer are our listeners questions about dreams?

00:43:02
Speaker 1: So Gin know, when do we dream? And why do we dream? Tell us about dreams?

00:43:08
Speaker 5: It's a great question, and we can only study dreams in people because we can only ask people about their dreams. It's a hard one because you can only ask people about their dreams when they're awake, so it's kind of a retrospective study rather than a live study. However, we do dream most when we're in rapid I'm at sleep, when our bodies are actively inhibited from acting out those dreams. So that's a good thing.

00:43:36
Speaker 3: But how do you know that if you can only ask people about their dreams later.

00:43:39
Speaker 5: Yeah, you just wake them up out of different stages of sleep, and when you wake them up out of round sleep, they're most likely to report having had a dream, and the dream is most likely to be the most bizarre and lengthy. So if you wake them up out of stage two sleep, which is not the deep slow wave unconscious state, but rather the first state you go into when you're sleep, and then the state that you go into right before rem sleep, so it's called a transition to rem there are more dreams, but they are usually very very brief, also bizarre, but they're not long stories. Usually they're just short, little snippets. So when we wake people up out of deep slowly sleep, which is hard to do because there's a lot of sleep inertia. And you ask someone what they were dreaming, they'll say, I have no idea, I wasn't dreaming anything. Let me go back to sleep, you know, grunt and turnover. Right. It doesn't mean that definitively people aren't dreaming as slowly sleep. It might just be that they are not remembering it when we wake them up.

00:44:41
Speaker 3: But do you have any way to know that their reactions, or their stories, or their retelling of their dreams correlated at all to their real dreams.

00:44:48
Speaker 5: Yeah, so there is some evidence, but it's controversial, or it has been controversial, because there was this idea of activation synthesis, so that in fact, you just have little blips of randomness when you're an in ram sleep and then when you're awake. Because we don't like little blips of randomness, we sew them into a story. And that dream isn't actually a story, but we've sewn them into a story. And there's some a little bit of evidence for that. For example, if you have an alarm waking you up, you will have a dream that can incorporate that alarm. Not everybody does, but you can have a dream that incorporates that alarm that starts before the alarm started ringing. Like, for example, in your dream, your alarm is a ticking bomb and you have to diffuse it. But in your dream, you're coming up up on the bomb and then you start hearing the ticking And so is it that you've retroactively dreamt about the silence before the alarm starts ringing in order to make this a story or is it that you know We don't know the answer to that. But interestingly, because we can put electrodes in the brains of rats, actually I want to tell you that it doesn't hurt to have an electrode in your brain. With these people with electrodes in their brain for epilepsy will not report any having any pain. Lead actually, strangely, don't have sensory structures in our brain to sense what's there. So rats with electrodes in the brain will not know that they've got electrodes in their brain, and they will sleep wonderfully. They will sleep beautifully, and you can see because you can control what happens to a rat during the days. You know, rats exploring a maze during the day and they're finding food in your maize. They will re dream about that maze. They will reactivate the same neurons that are active in a particular order during the day will reactivate in that order during their dream state of rapid eye movements sleep. And you'd say, why would they dream about the same thing that they were doing during the day. Well, they have a pretty boring life except for that exciting running time, and so they're much more likely to activate that particular dream. But there are a lot of times in rem sleep where they're not activating that daze. And so what are they dreaming about? We don't know. We would have to record every minute of their lives in order to see what they're reactivating and what they're dreaming about. But we do know that they do reactivate the maze, and interestingly, they can reactivate the maze in the same order in which they ran at during the day. But they can also do bizarre things that they can't do during the day, like leap from one side to the maze to the next, like we can in our dreams. We can change scenes, right, we can. You know, suddenly we're in a boat, you know, versus before we were in a house. So and rats can do the same thing. So we can't ask them about their dreams, but we can see their brain activity reactivating this reality that they were in the day before. Also, we have this tiny little brainstem area that inhibits our muscles when we're dreaming so that we don't act them out. When that tiny area of the brain stem degenerates, we act out our dreams. That's called RAM behavior disorder, and people with that have to actually tie themselves down while they sleep so they don't you know, hurt themselves because you're completely insensitive to the world around you. You are totally in your dream world and you could you know, fall downstairs, or walk through a plate growth glass window, or beat your bed partner because you're dreaming about, you know, an alligator over the side of your canoe. So you can also lesion that tiny little area of the brain stem in a rat and see the rat act out their dreams as well. So they will be you know, cowering as though they're dreaming they're being predated upon there's somebody spraying on them. They can fight, they can walk around, they can you know, phantom eat if it's a I've seen the cats do it. They can you know, swat at imaginary butterflies and also pounce on the imaginary prey. So yeah, this is some evidence that all animals seem to dream, including cephalopods which have this flashing of their camouflage while they're in that state.

00:49:13
Speaker 2: So we think that's a dream where their body is physically responding as opposed to that's just okay, huh.

00:49:22
Speaker 5: Yeah. So what is the origin of dreams? We don't know. But there is another part of the brain stem that only is active during rem sleep, so during this dream state, and it's filled with big excitatory neurons that project all over the brain, and it starts firing when we are in that end to stage of sleep, which is the state when if you wake someone up, they'll report little short dreams but not long ones, and then it fires like crazy when we're in ramsleep, and it might be the origin of the internal origin of dreams. It's right beneath an area of the brain brainstem called the locus th realist, which gets all sensory information from the outside world, and that is actively inhibited when we are in remsleep. But just beneath that is this area that comes on and comes alive when we're in dream state. So it might be the way we feel things and hear things and start speaking and all of that. Because this suberlist area it's called subserulists projects all over our cortex and we don't know because we haven't been able to control which areas are active and which are not active in the subscuos. To try and control and formulate a dream, like an inception of a dream, we can't do that yet, but maybe someday we will be able to do that.

00:50:48
Speaker 1: Wow.

00:50:49
Speaker 2: So there are a lot of people who are interested in interpreting dreams and trying to decide like what they mean, is there any hidden meanings in dreams or is it what's the science there?

00:51:01
Speaker 5: Again, that's really difficult because again you can only study in waking people. But there is a reactivation of memories. If you deprive someone a person of rem sleep, you will get a much more pedantic mindset. You can't deprive the people of remsleep for very long. That's again independently regulated and if given any nap opportunity. Normally, rem sleep comes after about ninety minutes or eighty minutes of sleep. It's it follows slow wave sleep because your brain needs to be in the perfect state temperature wise, et cetera, in order to go into this dream state of sleep. But if you deprive someone of particularly that dream state of sleep, they will go into rem sleep earlier and earlier because and get more, They'll get more and more of it, and then in fact, just at sleep on set they can go into rem sleep. There does seem to be a lot of anecdotal evidence that that dreams do relate to things that we're experiencing, and for some people more than others. A lot of people don't remember their dreams at all, so they're not the ones to study for this, but those who can remember their dreams sometimes it. In fact, dreams do seem to relate to the things that you've learned during the day or the week before, the month before, and the bizarreness of dreams seems to allow us to put things together. So we wake up with an aha moment, not always, but sometimes with an Aha moment where we've put things together that we couldn't you know, our conscious brain just couldn't let us put together. So the study of dreams and creativity does show that people, for example, doing a task that requires a creative insight in order to do it quickly. About a third of the people doing this task get the creative insight while they're awake and doing the task in the first place. Two thirds of people don't see the hidden rule that allows them to take the shortcut, and of those, half of them through sleep wake up and then can do the creative leap, and then a one third seem to never get it so unfortunately, and those that make that creative leap seem to have a lot more activity in this area of the brain that causes sleep spindles, which is related to these subsrulist area which causes these this activation, this random activation during dreams.

00:53:28
Speaker 3: Are you saying that people have this idea solve a problem while they're asleep, and then they wake up and they have the solution, or that the sleep is somehow prepared their brain to be able to solve this problem.

00:53:38
Speaker 5: It seems like they wake up with the solution so that the first time that they're doing it, you know they they've got it.

00:53:45
Speaker 3: So it is possible to dream up the great American novel.

00:53:48
Speaker 5: Yes, I think so, all right. There's one famous songwriter who said that when he wakes up. If he doesn't write down the song that he was dreaming about, God will give it to Bob Dylan.

00:54:04
Speaker 1: That's excellent.

00:54:06
Speaker 3: So what do we know about the cultural dependence of sleep and dreams? Do people sleep the same way around the world, Do they dream the same way? Do we have the same relationship with dreams around the world.

00:54:16
Speaker 5: There are cultures that have strong beliefs that these insights that come through dreams come from ancestors. That are you go to visit your ancestors and your dreams and they give you wisdom. Again, there's no scientific evidence, but there are, you know, cultural norms surrounding dreams that are different in different cultures. There's also cultural norms surrounding sleep in general that differ between different cultures. Some cultures don't value sleep at all. It's for the lazy, they believe, and there's nothing good happening except just turning off your brain and resting, and if you're tough, you can do without it. Other cultures have a much more an open or receptive view of sleep, and sleep is something they welcome each night and you with open arms, because that's a time when you know, lots of things happened, like consulting with your ancestors or whatever it is. There's a really cool study in South America by a researcher who's actually at University of Washington in Seattle. He put sleep trackers on people in a village without any electricity in South America in the Amazon, and another set of sleep trackers on people with bare minimum electricity like a single light bulb and a ceiling, and then on people living in the city. And he found that all of these cultures, no matter where they were living, sleep less during the full moon or the new moon. So he was tracking them for a full month and there's a statistical significant difference where people sleep less either the full moon or the new moon. And so you think it's not light because the new moon there's no you know, there's no moon and the only light you see the stars when you're out in the Amazon, if that at all, So it can't be light disturbance. And in fact the people in the city also these are college students, they typically spend very little time looking at the moon or thinking about the moon, so's it seems to be the only explanation that they could come up with in his paper is that the gravitational pull is stronger on the Earth during both a new moon and a full moon, and so maybe there's something have to do with gravity and sleepiness.

00:56:46
Speaker 3: Maybe that explains why we sleep worse at high altitudes. I always thought that was the oxygen.

00:56:51
Speaker 5: Yeah, No, the oxygen definitely does disturb a sleep. Yeah, yeah, I don't know what.

00:56:56
Speaker 3: About people who have different sensations of the world. Dreams play a different role in folks who have always been blind, Yeah, always been deaf. Can people see in their dreams if they're blind.

00:57:07
Speaker 5: No, they do if they're not blind from birth, but if they're blind from birth, so no, it's different sensations that are that are activated in dreams.

00:57:17
Speaker 1: Daniel, do you want to ask your alien question?

00:57:19
Speaker 5: Oh?

00:57:19
Speaker 3: No, right, So we've asked you about whether sleep is something that's common across Earth creatures. How common do you think it is across the universe? When aliens come and visit, are they going to need to take naps in between our conversations or do you think this is something that happens only on Earth?

00:57:35
Speaker 5: Well, it does happen on Earth. But whether or aliens sleep is a good question depends on what Whether aliens need to repair dumble stranded DNA. Do they have double stranded DNA. It depends on whether their energy stores works the same way. That's a great question because there are people who would like to do away with sleep altogether. They think the foo ones who think it's a waste of time, or who would like sleepiness to not affect people's performance, for example. But we have not found anything on Earth at least that can replace sleep itself, and in fact, without sleep, eventually we die, and that eventually is about as long as we take to die without any food, So it's as essential as food for us. So yeah, it's quite possible. There are aliens who don't need sleep work differently.

00:58:30
Speaker 3: Well, when the aliens do arrive, I think I hope that they're invertebrates so that you can do all sorts of terrible experiments on them. Yeah, I understand.

00:58:37
Speaker 5: No, no, no, no, no.

00:58:39
Speaker 2: I think they're coming up with new rules for working on like octopus as well, because oh yeah, they're particularly intelligent.

00:58:46
Speaker 1: And yeah, it's more complicated.

00:58:48
Speaker 5: There are already rules for activists. Yeah, absolutely, yeah.

00:58:52
Speaker 2: All right, Well, thank you so much for chatting with us about sleep and dreams. This has been fascinating and let's go ahead and hear if our listener had questions answered.

00:59:01
Speaker 4: Thanks for doing your podcast on this. It was really interesting, Doctor Poe was really interesting. I've never knew that people believe they talk to their ancestors in their dreams. I found that fascinating. Thanks for everything you do and I'll look forward to hearing all your future podcasts. Byebye.

00:59:25
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