Shush! The Creatures are Sleeping


Full Transcript

Announcer: Welcome to Stuff to Blow Your Mind from howstuffworks.com.

Robert Lamb: Hey, welcome to Stuff to Blow Your Mind. My name is Robert Lamb and I'm a senior writer here at howstuffworks.com. And with me today is Julie Douglas, who is a long time writer, editor, pyrotechnician here at howstuffworks.com. Welcome to the podcast, Julie.

Julie Douglas: Thanks, Robert. I'm excited to be here.

Robert Lamb: We're going to be taking the podcast off in an entirely different trajectory now. Previously, we were Stuff in the Science Lab. Now we're Stuff to Blow Your Mind. It's kind of like a joy division to new order Jefferson airplane to Jefferson starship kind of shift here. The old version was great, but the new version's going to be even more amazing.

Julie Douglas: That's right. We have everything from Are Cats Shape shifters to Why are We Existing Here in this Universe. We're just going to open the portal and we're going to start the new iteration. All right. Let's get this started.

Robert Lamb: Yeah, let's do it. As it happens, we are both cat owners. So we are very familiar with the sight of a cat in its various stages of sleep. It seems like they have many, just based on their bodily position.

Julie Douglas: It's true. They're elaborate sometimes. I really love watching my cat in slumber. And I look at him sometimes and think, "Oh, my god. Why can't I be you? You just seem like the master of the universe here in your 16 hours of various positions of sleep."

Robert Lamb: Yeah. We refer to our cats sleep levels based on what kind of bread product she resembles. So there's bread mode, where she looks like a loaf of bread. And then when she gets really relaxed, she goes into full on bagel mode, where she's very circular. She kind of looks like cinnamon bun. So they do sleep a lot. In fact, the total for cats is like 50.6 percent of the day, give or take, upwards of like 12.1 hours.

Julie Douglas: Yeah. And I would say my cat's more on the 16 hour. He seriously just doesn't do a whole lot. And I don't know if that's because he's a Maine coon and he's this 26-pound cat that's the master of the universe, and he can do whatever he wants. So if he wants to sleep for 16 hours, it's going to happen.

Robert Lamb: It's interesting. Obviously, most humans with jobs and responsibilities don't sleep 12 hours a day. So it's more like in the 6-8 range. And you see a wide variety of sleep patterns throughout the animal kingdom. So that's what we're going to be chatting about today. Do all animals sleep? And what does that consist of for different members of the animal kingdom?

Julie Douglas: Yeah, and why do our cats sleep so much? I think that is actually a universal question that has got to be answered. So we're going to try to do that by first approaching sleep.

Robert Lamb: Yeah, what is sleep?

Julie Douglas: Sleep obviously, is very important. It is profoundly important for our existence and how we operate physically, mentally, and emotionally. And I think we take it for granted and we think we just close our eyes and we wake up and we get going. In fact, there's so much more going on. And I think we need to revisit the basic quickly just to get an idea of how complex sleep is. So let's just do a quick recap. I'm sure we've all heard this in school at one point or another, but you know that there's stage one, which is the lightest sleep. And that's when we start to relax our muscles a little bit.

Robert Lamb: Is this the point where you're reading your book at night and you suddenly start reading words that aren't actually in the book?

Julie Douglas: Yeah, they all just sort of meld together. And this is also the point, too, where you feel like, "Oh, gosh. This feels so great." That little voice in your head thinks, "Oh, I've fallen asleep. That's awesome." And then all of a sudden, you feel like you're tripping or falling. And that's really your muscles working themselves out. So that's stage one. And stage two is when your breathing patterns and your heart rate start to slow down a little bit and your body temperature takes a little bit of a dip. And then stage three are when the delta waves start to roll in and lull you into a deeper sleep, although you're still fighting with that lighter sleep.

And then stage four is known as the delta sleep, which sounds like you should say the delta sleep - it's that really slow wave. And that's when you're getting 30 minutes of truly deep sleep. And that is also when you're capable of sleepwalking. So I don't know if you ever sleepwalked when you were little.

Robert Lamb: No, I don't think I did.

Julie Douglas: No? I did a lot. So my parents would see me cruising through the house at 3:00 a.m. and my hands would be up like Frankenstein because I literally thought I was Frankenstein. I was rolling around the house like that.

Robert Lamb: Wait, in the dreams or just as a child you were convinced you were Frankenstein?

Julie Douglas: In the dream.

Robert Lamb: Okay. Because kids are weird. That kind of thing happens.

Julie Douglas: That's kind of awesome. I wish I had been a kid who had thought that she was Frankenstein. I could really freak out the neighbors and just scream, "Fire!" That sounded like Robert De Niro's Frankenstein. Sorry about that. And then stage five is when REM occurs. So that's when you're dreaming and that's when you're really working things out, all that data that you've processed throughout the day. And that's also where you might be having a dream that a dog is mauling your face - god forbid.

Robert Lamb: And a dog might be having a dream where it's mauling a human's face.

Julie Douglas: Exactly.

Robert Lamb: Two totally different -

Julie Douglas: Parallel dreams at the same time. And the cool thing about this is you have a built-in paralysis mechanism to make sure that you don't freak out during that time period. So the dog doesn't leap out and try to bite in its dream and I don't try to take the dog off of me and smash it or something violent like that.

Robert Lamb: Interesting. So any of these episodes you hear about where somebody's having a dream and they start strangling their spouse, that's not in this stage.

Julie Douglas: No, no. I think there's something else going on there.

Robert Lamb: Yeah, I'm probably thinking of Ozzy Osbourne, so there could've been any number of things.

Julie Douglas: You have to wonder, too, if there are certain medications or substances that might be messing with the natural rhythms.

Robert Lamb: I don't know that Ozzy was ever on anything, but -

Julie Douglas: No, no. That's pretty farfetched for him. But you never know. There's certainly external forces that could be acting on that.

Robert Lamb: So we're in this stage. We're dreaming. The brain's being cleared up.

Julie Douglas: Yep. And we're going through these stages about every 90 minutes. So there's a ton of stuff that's going on. And we're also flailing around, moving around. I think I read a stat somewhere that we move around at least seven times per hour. So it's not just the slumber that we think of that's all peaceful and the cat's curled up by your head.

Robert Lamb: I need that stat the next time I'm kicked out of bed at 3:00 in the morning for moving too much.

Julie Douglas: Yeah. See, that would be helpful. Maybe.

Robert Lamb: Maybe. Probably can't actually present the stats at 3:00 in the morning. "Whoa, wait. Slow down. Check out this study in Scientific American. I'm totally supposed to move around. You should be concerned if I'm not kicking you in my sleep."

Julie Douglas: Yeah, on second thought that might exacerbate the whole situation. So it's good to have an understanding of what sleep is because that's the model that we use to study other creatures. We know about theta waves, delta waves - you know that when they go into these slow low wave states that they're brains are preoccupied and they're dreaming or sleeping. That's what we assume, at least. So taking that data, we can now look at our cats and measure whether or not they are actually dreaming - although, it's obvious to us. Especially when they're twitching around and chasing mice, or whatever they're doing in the dream. That still doesn't necessarily answer why they are sleeping so much.

So that's something that we can look at a little bit closer. But I think in the case of our cats, it may be that we've done everything for them. I'm going to go out on a limb here. Because they don't necessarily have to hide from predators. They have a food source. So they're all nice and cushy. So some people say that they just don't have the impetus there to be more of a predator themselves and spend more time awake.

Robert Lamb: Well, certainly for totally indoor cats that would be the case.

Julie Douglas: Yeah.

Robert Lamb: Ours goes outside and kills things and probably has to avoid things every now and then.

Julie Douglas: Oh, so that might be why your cat is sleeping 12 hours and my cat is lounging around for 16 hours.

Robert Lamb: Yeah, it's like, "Hey, there's nothing going on here. I'm going to go into the chipmunk dream."

Julie Douglas: Exactly. "It's kind of boring here." That, or sometimes I think of the movie Inception. Have you seen that? Sometimes I think that my cat's just practicing to put some sort of thoughts in my subconscious when I'm actually dreaming.

Robert Lamb: They probably are.

Julie Douglas: Is that crazy cat lady talk?

Robert Lamb: A little bit, but you spend enough time with a cat - those guys are weird.

Julie Douglas: Thank you for comforting me.

Robert Lamb: Another thing about cats and their predator nature, I've read some arguments that if society were to fall apart and humans were gone the next day - all the cats would obviously go feral - but domestic cats would have a better shot at surviving as a species because they continue these rehearsals for privation. Even if they're not hunting, they're attacking things in your living room. They're continuing the exercises. It's like a constant terrorist training camp in your living room. While many breeds of dogs, we've either perverted their natural hunting instincts into something ridiculous where we end up with a Collie that wants to bark at trees.

And they don't really have a skill set anymore. They'd be as useless as writers in the apocalypse.

Julie Douglas: Wow. I don't know. Writers - you're right. They would languish with the dogs. They would begin barking at the trees.

Robert Lamb: Probably so.

Julie Douglas: Well, we have animals that are clocking in a lot of sleep, a little sleep, and -

Robert Lamb: Yeah, they're all over the board. Like we mentioned, the cat is coming in at half the day, roughly. And we should mention that you'll find varying figures on all of this out there on the net. Sometimes a captive animal's sleep patterns versus a wild animal's sleep patterns - and it's hard to get a lot of sleep when somebody's trying to eat you.

Julie Douglas: That's true. And it makes sense, too, because the ones that are captive, it's hard to measure some animals. So some of them would have to be captive in order to get some data off of them.

Robert Lamb: At the low end of the spectrum, it's hard to beat the giraffe, which is almost two hours a day - about 7.9 percent of the day. And you see that the horse is really low at 2.9 hours; the donkey at 3.1 hours. It's interesting, because I guess some of these animals you're thinking, "These guys are always on the run." They have to always be ready to just take off at any moment to avoid a predator. So they apparently evolved into this state whe re they don't need much sleep.

Julie Douglas: Which I thought was odd. The giraffe, I understood. I thought, "Okay, if I'm a giraffe and I'm out in the wild, I'm going to be scared that something's about to put its teeth into my neck." But the cow, not necessarily.

Robert Lamb: I guess the cow's one that's like the dogs. We've perverted the species over time where they don't really have anything to worry about. But maybe some original version of the cow was more survival.

Julie Douglas: Yeah, that would make sense. Absolutely. And then I thought it was cool about the giraffes, that they sleep sometime five minutes at a time.

Robert Lamb: Oh, really?

Julie Douglas: Yeah. And they're very efficient sleepers. So they're not piddling around with the stage one. And they're not having dreams about tripping or falling. They go straight into deep sleep, which I really admire. I want to try to cultivate that for myself.

Robert Lamb: Yeah, they've really streamlined the process to get right to the goods, the bare minimum, to remain functional and sane, I guess.

Julie Douglas: Yeah. They're the Martha Stewart of the animal kingdom. They're being very efficient about how they spend their time sleeping.

Robert Lamb: Well, the elephant is pretty high up there. And what's trying to eat an elephant?

Julie Douglas: Yeah. There's also the brown bat.

Robert Lamb: Oh, the brown bat's on the other end of the spectrum at 82.9 percent of the day - 19.9 hours of sleep.

Julie Douglas: Yeah. Those suckers are layabouts.

Robert Lamb: The thing I was reading about the brown bat was that they're flyers. And to fly with wings in this world requires a huge amount of energy. That's one of the reasons you don't have airplanes with flapping wings, because it might look cool in the Sci-Fi movies or cartoons but it would require a tremendous amount of energy that just doesn't make sense when you have propellers. Bats don't have propellers, so they've got to flap. And by flapping to get things rolling in the air, they're expending a lot of energy. And they're eating mosquitoes and stuff. So sometimes the best course of action is to just turn it off for 19 hours.

Julie Douglas: Yeah, and it would make sense, too, that they might hide themselves away from predators. Or if the mosquitoes were only going to be out for a couple of hours -

Robert Lamb: That's right. Most of your bats are seeking shelter in high trees or in caves, and they'll be in a situation where they really don't have to worry about predators so much, either due to their location or their numbers.

Julie Douglas: Yeah. Another creature on this list is the tree sloth, which is one of my favorite animals. I don't even know how to describe what it looks like other than just a hairy looking alien.

Robert Lamb: Yeah, like a mossy hairy alien.

Julie Douglas: Like Muppet, even, too. It's like the Muppet that just didn't make the cut.

Robert Lamb: Yeah, they're somber-faced. The baby sloths are cute. But the adults are kind of like Muppets.

Julie Douglas: Yeah, and it's cute but menacing at the same time, which is I think why it wouldn't have made the Muppet cut. But they're named sloths obviously because they are very slow moving creatures. In captivity, they actually sleep for 14 hours, but in the wild they sleep for 10 hours. So that really mirrors more of our own activity. So just so I can clear up their name a little bit because they're already saddled with the moniker sloth. I just want to get that out there for the sloth world. A little shout out.

Robert Lamb: Now human infants are pretty high, too - 66.7 percent of the day, 16 hours.

Julie Douglas: They're crazy high, which makes sense because we've talked about the data that you're processing during sleep. And just think of all the stimuli. You've been shut in the womb for almost ten months.

Robert Lamb: Yeah, everything is new. Light is different.

Julie Douglas: Yeah, some sound is familiar, but some sound isn't. So it's building that database that they have to do. So are there any creatures that require zero sleep or different types of sleep? How does that work?

Robert Lamb: Well, that's the question. There are certainly animals who, for starters, can disrupt their normal sleeping patterns for certain special events. Like migratory birds, they've got to suddenly go into overdrive, travel long distances - so they can alter how much sleep they need. Now fish and amphibians are some creatures that we're still not completely sure on whether they're sleeping or whether they're just exhibiting resting signs. And again, the typical signs of sleep - generally you're looking for a reduction in physical activity, decreased response to outside stimuli, and generally a sleeping creature will assume a certain position. Back to the cats - same thing.

So we don't necessarily observe these things going on with fish and amphibians, so the jury's still out.

Julie Douglas: So a jellyfish could be at the way deep bottom and they might have successfully attached a tracking device to it or something and there's a period of inactivity. And you have to assume that maybe they're in a resting state. Is that -

Robert Lamb: Yeah, that's kind of how it goes. But again, it's like you were saying earlier. We base a lot of it on the human mind. And we use that as the model to try and understand everything. And in some cases, like the jellyfish, we're so distantly related that maybe it doesn't hold up.

Julie Douglas: Right. We're anthropomorphizing ourselves again.

Robert Lamb: Everything. Now one of the really cool areas of sleep is unihemispheric sleep, as in the hemispheres of the brain.

Julie Douglas: The two hemispheres.

Robert Lamb: Imagine you have a company with 90 employees and you're open 9:00-6:00. And then you decide, "All right. We need to actually be open all the time."

Julie Douglas: Wow, that's like Wal-Mart.

Robert Lamb: So you're like, "All right. Well, we can't have all 90 employees work all the time because they'll quit and leave or riot. So let's have 30 work here, 30 work here" - and you end up mixing it up. That's pretty much what animals such as dolphins and other aquatic mammals do. They're conscious breathers. So if they were to go to sleep, they wouldn't breathe and they would die. So they've got to be awake in some fashion all the time. So they just turn one hemisphere of the brain off.

Julie Douglas: Is it a function of their biology? Or is because they're worried about predators - or both?

Robert Lamb: Well, there's that, too. The ocean is an intensely dangerous place. Even if you're a dolphin hanging out with other dolphins - they're pretty rough and tumble characters. But still, there's constantly something trying to eat you for the most part. I understand that horses - and even joggers - will stand on one leg and rest the other, and then switch to the other leg and rest that one. It's the same thing, except with the brain. So turn one side off and let it rest while the other one powers everything. And then do the opposite. So you're never turning off both sides of the brain and letting both sides sleep at once. But one side is sleeping while the other remains awake.

Julie Douglas: So that allows you to react quickly and just be a more efficient dolphin.

Robert Lamb: Yeah, it's never a situation where, "Oh, I've got to wake" - this actually goes back to when you're asleep and you have a dream where you're falling and you fly awake. There's some interesting studies, mostly from psychologist Frederick Coolidge - he's talked about this on radio lab before, I believe. He argues that the idea of having a falling dream come from early history where we were sleeping in trees.

Julie Douglas: Oh, wow.

Robert Lamb: So you're sleeping in a tree, so if you fall out of that tree there's probably all sorts of things waiting for ape creatures to plummet from the branches so they can gobble them up. So if you feel like you're falling, instant awake, because you've got to protect yourself. You've got to grab back onto the tree and stay put. So they think that's an evolutionary remnant of those times.

Julie Douglas: That's so cool. For some reason, that just reminded me of my college roommate who was constantly falling from her bunk bed.

Robert Lamb: But she fell completely off of it?

Julie Douglas: Yeah. Again, external forces acting on her, I think.

Robert Lamb: She would've totally been eaten by wolves in the old days.

Julie Douglas: I know. Her and Ozzy Osbourne.

Robert Lamb: Both of them. And I don't think I ever get the falling dreams, but I'm always getting these dreams where I'm drifting off to sleep a little bit and then I'll dream that I'm slipping on something, like on a linoleum floor. And I'll be like, "Whoa."

Julie Douglas: Mine is a sidewalk. I don't know. I'm going to see if I can lucid dream next time and put a banana peel there or something, just to make it a little bit more interesting. I'm going to try that out.

Robert Lamb: But back to the unihemispheric sleep. Again, this is us using our mind as the model. It's difficult for us to imagine what this would be like, but scientists think it might be some sort of semi-conscious state, like we experience when we begin to fall asleep. So it would not be the same as being awake. You would be operating everything at half power, but still awake enough to immediately respond to something. There's no, "Oh, I think I'm falling. I'm going to wake up." It would be like, "There's a predator. I'm going to cut."

Julie Douglas: So for my cat Owen, I have to say that I think I've actually observed this in him before.

Robert Lamb: Oh, really?

Julie Douglas: He's looking at me - I think this is why cats get such a bad rap sometimes and are called creepy. But he'll sometimes look at me with one eye open and it'll be slightly rolled back. So I know that he's in some sort of sleep state. So I have to wonder if it also extends to other animals.

Robert Lamb: Well, this is interesting, just in trying to figure out what unihemispheric sleep might be like. There's a book called Consider Phlebas by Iain Banks. I don't know if you've read anything by him.

Julie Douglas: No.

Robert Lamb: He's written a lot of just straight up fiction like The Wasp Factory, and he's a Scottish guy. He's also written a number of Sci-Fi novels, and Consider Phlebas was the first book in the Culture series. It's like a space opera thing, but he throws in a lot of cool science and philosophy. It's nice brain fodder, as far as Sci-Fi goes. But in this book, there's a character named Kraiklyn who has "enhanced hemispheric task division" in his brain. And the way it works is that he's doing exactly what the dolphins do, but because he's a dangerous mercenary and has to be on alert at all times. So one-third of the time one-half sleeps, so he's a little bit dreamy and vague.

And another third of the time, he's all logic and numbers and he can't communicate all that well with other people. And then for the other third of the time, he's completely awake. So I found that interesting because obviously Banks was trying to imagine who unihemispheric sleep would translate to the human experience.

Julie Douglas: To the left and right brain. So you're right. So one part of us would be analytical and the other part would be composing arias.

R obert Lamb

Yeah, it would be weird life. It seems like you'd have to want to line up and coordinate with your coworkers, your spouse, or significant other. You'd have to organize your life along which part of your brain was functioning.

Julie Douglas: Well, I think you'd have to color code yourself. Everybody would, because it wouldn't be just you. It would be everyone.

Robert Lamb: Yeah, that would be interesting, a world where everyone has unihemispheric sleep. You'd have to be like, "Oh, I can't ask Julie about this right now because obviously she's all numbers and no speech."

Julie Douglas: She's all green shirt today. Forget it. See, I'm already trying to organize this. I'm intrigued by it. Well, we've got unihemispheric sleep. We also have something called torpor, which is a reduced version of hibernation. And I think we should probably just mention that.

Robert Lamb: Yeah, because people might be thinking, "Hey, how about bears? Aren't they sleeping for months?" Not really.

Julie Douglas: Right. They're taking their bodies down to the studs so to speak. They're just shutting everything down. So there's not much brain activity there. But torpor is a not so extreme version of hibernation. And that's found in hummingbirds.

Robert Lamb: Yeah, we were talking about this earlier. They mentioned this in Attenborough's The Life of Birds at one point. We were talking about how much energy it takes to fly. And hummingbirds are the extreme of this. They consume a colossal amount of energy.

Julie Douglas: Yeah, their heart rate is 1200 beats per minute.

Robert Lamb: Yeah, they're completely inefficient.

Julie Douglas: Yeah, so when they go to sleep, they seriously knock themselves out pretty much. They hang upside down like a bat and they sleep overnight. And this is actually called torpor because it's not necessarily what we think of as sleep. It's a lighter version, again, of hibernation. But they need that time period because they're not very efficient at conserving their energy. So you can go up to a hummingbird and just tap it and you might think its dead. It actually won't even react. But that's how it's getting it's Z's and it's another interesting way to think about sleep. I know at some point this is sort of semantics. We think about sleep, hibernation, torpor - but it's all about just shutting it down.

And there's a reason why we do that, because we've got to get the benefits of sleep.

Robert Lamb: Yeah, what's the payoff? What's Owen, or in my case Biscuit, doing all this time when they're -

Julie Douglas: Well, I think with Biscuit and Owen - again, because they're not out in the wild - they're not recharging as much as a human would. But they're definitely working through the data and they're processing. And who knows? We don't know what they're dreaming about, but like you said their skills are still intact. You've got to wonder if they're still putting themselves through the paces, like a cat terrorist training camp. So they may just be putting themselves through their exercises and jumping through hoops and whatever they do in dreams. So one of the things we know about sleep is it helps us to repair all the muscles and the tissues. It also helps us review the data we've taken in.

And it makes us more adaptive to the environment around us. Because every day there's something new that you're taking in. It could be that you're driving to work and you see the sunlight dappling a leaf. But you're not necessarily going to dwell on that. So your brain just files it away. And that might be something that it recalls later, just as part of a vast amount of data it has to sort through. So I was thinking about this and I thought, "What is the most extreme version of the benefits that we know of, that we could study?" And that would certainly be human infants.

As e have mentioned, they sleep up to 16 hours a day, and about 50 percent of that time, they're dreaming. So that's an organism that is working hard at developing neuropathways and doing all sorts of crazy things to try to get its body bigger faster, its mind bigger and faster. The human mind actually develops in the first two years 70 percent of its mass. So they're doing a lot of work there. So that's a cool thing to look at. Because if you compare it, human adults are actually spending about 25 percent of their time dreaming. So think about the human infant. It's building up its own new fresh database. And you take that model and you start to apply it to other forms.

There's a study that MIT did with rats, saying they were performing these repetitive tasks. And then they were sleeping and they were performing them again. And they were doing exceedingly well. So we know this in humans, too. You learn something, you sleep, and all of a sudden you're like Keanu Reeves in the Matrix. Well, you're not that good, but -

Robert Lamb: But still, when people say, "Oh, I need to sleep on this."

Julie Douglas: Yeah, exactly. And was it Roosevelt who wouldn't make any major decision without taking a nap? I thought that was pretty great.

Robert Lamb: Yeah, he always carried a cot with him. He would be in the middle of an International conference and someone would ask him a question. He'd be like, "I don't know." They'd pull out the cot and eight hours later he'd have an answer.

Julie Douglas: See, I want to do this at work. I don't know how well it would go down, but I think it's worth a shot. I'll try to introduce that. And then you think about Paul McCartney, who claims that Yesterday was written in a dream. And he woke up and ran to the piano and got it down as quickly as he could. So if you think about the benefits of sleep, particularly for humans, it's a great place to repair your body and to also work through all the anxieties, fears, and hopes that you have in this sort of safe place. So it's like a black ward of the mind.

So if you apply that, if you look at the rats, you can see that the same thing is happening in other species - that rats too are taking data and running through it. And cats are, and they're coming out much better on the other end.

Robert Lamb: So it's like, just as our computers are running their defrag programs at 3:00 in the morning or scanning for viruses, it's like our dream cycle and our sleep is achieving the same thing.

Julie Douglas: Yeah, absolutely. Actually, when I was looking at a lot of this data, I was thinking about how much of this is so similar to a computer, which makes sense because humans created computers and it's based on the way that we -

Robert Lamb: You say that like maybe we didn't create computers.

Julie Douglas: Well, you've got some other theories blowing around there. I don't know if this is the space for them, but I'm not going to mention aliens. I'm not. I think it's important to also mention that not all creatures dream. We don't think reptiles dream.

Robert Lamb: I mean, look at them.

Julie Douglas: Yeah. I mean, come on. They've got primordial goo in their - I don't know. Actually, they're not exhibiting any sort of waves that we recognize as dreaming, so it may just be that we're limited in what we can sense in them. But I just think it's important to throw that out there. So we can really only theorize about the benefits of animals. Obviously, we can't go up to them and say, "Hey, giraffe. How does this benefit you?" But I think the difference between humans and animals is that for animals it's more about external forces. They're reacting to their external forces. They're behaving in different ways because of that. We sleep during the night because we work during the day.

They don't have those sort of pressures or concerns, so they may be sleeping when there's a predator around. So we know they're benefiting from it because they're not going to get eaten. So they're going to squirrel themselves away so to speak. So that's a benefit to them and it's something we can theorize about, but we don't have any definitive answers on how it's affecting them.

Robert Lamb: Now, we can definitely deprive them of their sleep and see what happens. And there have been a number of interesting/scary studies - creepy studies - about that. For instance, there was a Princeton University study in which they deprived a number of animals of sleep. And they found that like 72 hours without sleep results in elevated stress hormone levels and the animals end up producing significantly fewer brain cells. That again flows right back into what we're talking about with processing of all the stimuli, the recharging of the fleshy computer.

Julie Douglas: I like that - fleshy computer.

Robert Lamb: And they also found that, specifically we were talking about rats earlier - two weeks without sleep will kill a rat dead. And the same thing with other rodents, and even flies. We're not sure about all insects, but apparently they tried to deprive flies of sleep and found that flies died.

Julie Douglas: Which makes sense. I'm sure you've pulled an all nighter before, we all have.

Robert Lamb: Yeah, you feel horrible.

Julie Douglas: You feel awful. And if for some reason you did that two days in a row, then you're cognitive functions are going to break down a lot. You're going to have to wear your green shirt, "Half my brain is out."

Robert Lamb: I've also read that there's a specific gene that some people have. The re are some people who are like, "If I don't get my six to eight hours of sleep, I just can't function." And then other people seem to be able to pull the all nighters with a little more finesse. And there's a genetic marker for that they've identified.

Julie Douglas: Really?

Robert Lamb: Yeah. I don't have the name of it offhand, but I think we mentioned it in a previous podcast.

Julie Douglas: So it's not necessarily that they're lacking melatonin that regulates that. It's not necessarily that they have a little or a lot of melatonin, it's just that they've adapted somehow that way?

Robert Lamb: Yeah, it's just a different evolutionary adaptation. So it's one of the things where if some sort of space predator came down and started eating everybody that couldn't pull all nighters, then we'd only have that one variation of humans left.

Julie Douglas: I think it's good to know that. And I say that because I think I read somewhere that Oprah only sleeps six hours a night. And I was like, "Wow. Another way in which Oprah's making me feel like I'm not doing all that I should be." I love you, Oprah. So the fruit fly thing cracks me up. How exactly did they deprive them of sleep?

Robert Lamb: Yeah, I picture them poking them in the shoulder with a little stick.

Julie Douglas: Okay. I was thinking about these tiny little cigarettes they might've fashioned and some tiny little cups of coffee - keep the caffeinated and up.

Robert Lamb: Yeah, well when they talk about these animals being super stressed from not sleeping, it's like I would be stressed, too, if someone was preventing me from sleep. "What's this guy doing in my room poking me with a stick all night?"

Julie Douglas: Right. Enough with the tiny cigarettes. That reminds me, I've heard that when you're really stressed out during the day it does mess up your cortisol levels, which tend to peak during the nighttime hours. Usually, you're circadian rhythms would be stomping on that and making sure that wouldn't be happening. So I'm fascinated with that because I'm wondering if the same thing happens in animals, if their cortisol levels also go up, or if that's just a particularly human thing.

Robert Lamb: I don't know. If humans don't get enough sleep, they say at least degradation of memory. You can't hold as many facts. You're alertness level, coordination, judgment - everything tumbles downhill. So supposedly Keith Richards stayed awake for a week once.

Julie Douglas: See, I would never put him in the same column with Navy SEALS. But now I am.

Robert Lamb: Oh, I can't imagine a whole team of them.

Julie Douglas: A whole team of -

Robert Lamb: Of Keith Richards as a Navy SEAL stumbling into a secret hideout and mumbling about stuff.

Julie Douglas: [mumbling]

Robert Lamb: Well, there you have it, right? That's pretty much animal sleep. So do all animals sleep? A large number of them do. There's some we're not sure about, but sleep is different things depending on what your species happens to be.

Julie Douglas: Yeah. And we still don't know what our cats dream about. We want to know. We want to hear from you. Are your cats dreaming about something? Are they trying to plant thoughts in your subconscious?

Robert Lamb: Yes, let us know pretty much any thoughts you have about your cat's brain activity. We would be happy to hear it. So if you want to learn more about sleep and dreams, be sure to check out howstuffworks.com. We have articles like Do All Creatures Sleep by Jessica Toothman. We've got a couple of articles from Charles Bryant, Is Sleep Important, Why do we Sleep, and we even have How Sleep Works by Marshall Brain himself. Thanks for listening.

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