Did our brains evolve as they have due to how we slept? The answer is likely yes, at least in part. In this episode of humanOS Radio, I speak with Evolutionary Biologist Professor David Samson about his research on primate sleeping platforms (beds) and their potential roles in why some primates have developed more sophisticated mental faculties than others. The primates that create more comfortable beds for themselves appear to get substantial amounts of deep and rapid eye movement sleep over the night. This is turn may have led to advances in cognitive abilities over time.

Professor Samson works in the Nunn Lab at Duke University, which investigates reasons why humans develop disease from evolutionary and ecological perspectives. The lab is currently conducting projects on the evolution of sleep, the spread of infectious diseases in wildlife, and the factors that make humans different from other primates in places such as Ethiopia, Kenya, and Madagascar.

 

Differences in sleeping platforms and sleep between primates

In the interview, we talk about a direct comparison between sleeping styles of baboons (shallow sleepers) and orangutans (deep sleepers). In contrast to the orangutans, when the baboons are given comfortable sleeping materials they completely ignore them. They’re huddled together, and when a high-ranking baboon breaks the huddle, everyone scatters. It’s like a domino effect. The baboons sleep in a heightened state of readiness and therefore shallower sleep.

 

Check out this interview with @Primalprimate on how sleeping platforms (beds) have affected the evolution of primate brains! Click To Tweet

 

Unfamiliar sleeping platforms and sleep quality

Interestingly, the same week I recorded this interview, a paper came out entitled Night Watch in One Brain Hemisphere during Sleep Associated with the First-Night Effect in Humans. The paper describes how it’s common for people to experience trouble sleeping in a new environment. This is called the first-night effect. The study imaged the brains of humans during sleep and found that this temporary sleep disturbance is the result of different activity patterns between our brain hemispheres, described as “regional inter-hemispheric asymmetry of sleep depth”. The hemisphere with reduced sleep depth had enhanced excitation when the researchers introduced disruptive sounds and noises in the environment. Essentially, if you were sleeping at home in a familiar bed, you might sleep right through this. But since you’re in a new environment – one that you’re unfamiliar with – your brain is more attuned to environmental signals. This is undoubtedly an evolved protective mechanism, but it reminded me of baboon sleep – shallow and hyper-responsive to noises.

Finally, in case you missed it, I previously interviewed Jerry Siegel on how humans living in preindustrial societies sleep.

 

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TRANSCRIPT 

David Samson intro except	It may be that something very critical happened from the transition from the subsistence pattern that we’ve adopted for 99 percent of our species’ evolutionary history, the foraging, hunter-gathering subsistence pattern. There has to be some sort of consequence when we change to small-scale agriculture. There had to be some sort of effect on sleep and our sleep-wake pattern.
Speaker 3:	Human OS. Learn, master, achieve.
Dan Pardi:	Hello everyone. Today, I have evolutionary biologist David Samson on the show, who earned his PhD at Indiana University. He is now a post-doctorate associate, working in the Nunn Lab at Duke University as an evolutionary biologist, interested in human evolution. He is currently working or investigating the link between sleep and cognition in primates. This is an area of interest of mine.
[00:01:00]	David has lived in the Toro-Semliki Wildlife Reserve in Uganda, habituating wild chimpanzees and climbing African ironwood trees, which happen to be a favorite sleeping spot for Somliki chimps. He does this in order to understand the ape sleep sites better. At the Indianapolis Zoo, he studied the sleep patterns of orangutans, and was part of a team that tested the effects of sleep on touchscreen cognitive tasks. Very interesting. How well do these chimpanzees sleep, and how well did they then perform on iPad-like cognitive tasks? Probably some relationship to how we perform.
	Currently, he is leading similar research projects at Duke Lemur Center, working with the world’s largest and most diverse collection of lemurs outside of Madagascar. As a National Geographic grantee, he will be extending his work to one of the last hunter-gatherer groups of Africa, the Hadza. You might remember I spoke about the Hadza in my interview with Dr. Jerry Siegel from UCLA, as well as other small-scale societies. In his spare time, he practices a medieval martial art, and is also part of the Society for Creative Anachronism.
	Dr. David Samson, welcome to Human OS Radio. Tell us how you got into your field of research.
[00:02:00] David Samson:	Interestingly enough, it actually began in my dissertation days at Indiana University. My doctoral supervisor, Dr. Kevin Hunt, he ran a wild chimpanzee field site out of Uganda since the mid-90s. I was really interested in chimpanzee material culture, originally. One of the really unique things I discovered when I was looking through the literature in graduate school is that apes have this really bizarre, cool, universal behavior. They all build sleeping platforms. No other monkey does this, not even the lesser apes, who are phylogenetically very closely related to us. Not even the lesser apes, the gibbons, they sleep prostrate on branches.
[00:03:00]	I was interested in this behavior, so I went out to Somliki in Uganda and climbed these Cynometra Alexandria trees, which is an overwhelming preference for these chimps. I climbed these trees, and try and figure out why they were selecting Cynometra, which is a particular tree species, in an overwhelming majority compared to the other possible species that they had access to. It turns out that the Cynometra ape nests were biomechanically stronger than the other species, and even perhaps repelled insects. That was my gateway into being interested in sleep. It was originally just looking at sleeping platforms as a behavior.
Dan Pardi:	I have to say, you sound like the next generation of researcher and author Robert Sapolsky from Stanford University.
David Samson:	Wow.
Dan Pardi:	That is a pretty big compliment.
David Samson:	Yeah, I’ll take it as a compliment.
Dan Pardi:	If you’re not familiar with Robert Sapolsky, listener, he’s a biologist from Stanford. Not only is he a brilliant scientist, but he’s one of the best writers. He’s like a mixture of comedy and great science. Even if you aren’t interested in a subject, reading his work is just so entertaining.
David Samson:	Oh yeah. Totally agree. I’ve been a fan for a while. I saw him speak at IU actually, several years ago. He’s great.
Dan Pardi:   [00:04:00]	Yeah, yeah. What makes Sapolsky so great is his ability to not only immerse himself into the environment of his subjects. Not just studying baboons in a lab or in a zoo, but actually going to Africa, living amongst them for eight months at a time and collecting data on them, but then also being able to come home and translate that into an absolutely captivating story. If you haven’t read one of his books, A Primate’s Memoir, which is the story about his travels to Africa and doing his research, you must. It’s so entertaining, but it’s also so revealing about him as a character, but then also about our physiology. Go out and grab that book right away.
	Like Sapolsky, you did the hard work too. You put yourself into the environment of these primates to study them in their natural habitat. Why are the great apes sleeping in beds while lower primates aren’t?
David Samson:         [00:05:00]	That’s the operative question. That was the second part of my dissertation, was coming back home and realizing how interesting this behavior was and trying to get at the ultimate causation behind it. This is what led me to team up with Dr. Robert Shumaker. He’s at the Indianapolis Zoo. He’s the vice president of life sciences there. He’s worked with a group of orangutans for decades. What we did was, we experimentally distributed sleeping materials. I’m talking pillows, memory foam mattresses, blankets, sheets, all these different materials.
	We distributed it into the enclosure that the orangs were living in, and we didn’t have to teach them a thing. They just automatically built these really complex sleeping platforms. Then we had nights where they only had access to straw, and we tested their next-day cognition. What we actually discovered was that on nights where they had access to these really plush sleeping platforms, they scored higher on these cognitive tasks with greater accuracy.
Dan Pardi:	David, what type of tests were used to test their cognitive performance?
David Samson:         [00:06:00]	This was a collaboration at Indiana with Tom Schoenemann. He was interested in a question, can orangutans learn artificial grammar? They were given these touchscreen tasks where you had, say for example, ten faces. The orangs learned the sequence, the quote-unquote “grammar.” Then whenever there was a moment where that pattern was disrupted, say a face was out of place, they would pause. They would then take longer to be able to finish the task.
	Basically, this was a cool task, because not only was it discovering whether or not they can understand artificial grammar and learn artificial grammar, but it was a learning task. One of the functions of sleep, the proposed function of sleep, is memory consolidation. This gets at learning itself. Bringing it back to sleep, when they had those more comfortable sleeping platforms, they performed with higher accuracy.
Dan Pardi:	Well, there you have it. Primates sleep better when they get a good night’s sleep on a comfortable mattress. You know, it’s funny, over the last couple of years I learned a lot about mattresses. I didn’t know that much before, and you’d think maybe I would, just because I get a lot of questions on that subject. There was a study by Shawn O’Hagan, who looked at different mattress types. He had people feel the mattress, select which one they felt would be best for them, and then he had the people actually sleep on the mattress, look at their sleep, and then look at their cognitive performance the next day.
[00:07:00]	What he found is that people oftentimes choose the mattress that isn’t best for them. We’re pretty disadvantaged when we’re shopping for a mattress. We don’t have the chance to sleep on every one for a couple weeks at a time, and then take home the one that’s best. Also, your own perception about what’s best for you might actually not line up with … You might have a bias. I really love a soft mattress, but it might turn out that a firmer mattress, you might sleep a lot better on it.
David Samson:	Mm-hmm (affirmative). Sure.
Dan Pardi:	The Tempurpedics can be problematic because they feel good to the hand, but then you end up having higher peak pressure points. Because you sink into the mattress, there’s less distribution of body weight, and that can lead to higher heat in certain parts of the body, which can cause you to wake up. Your core body temperature, at least with some kind of small pilot studies, showed that it’s actually higher across the night. It’s kind of ironic. I wonder if the non-human primates made some of the similar choices that are slightly disadvantaged for choosing the most optimal platform for cognition.
David Samson:	Yeah, yeah. No, and I think that’s what the interesting results are, is that it’s very clear that they do have a preference. The whole critical thing was, what are these preferences?
[00:08:00] Dan Pardi:	Okay. Primates have preferences for sleeping materials, or materials to sleep on. How long do you think this has been going on for?
David Samson:	Absolutely, I think that’s a critical question. I think you can safely say that it began with the advent of the first proto-ape. You can probably take it back to the Miocene, maybe between 14 and 18 million years ago. I think the critical driver, and this is something I talk about in a recent publication with my colleague here at Duke, Charlie Nunn. One of the big drivers to transition from sort of the limb-nest transition was mass. You have an ever increase in mass throughout the Miocene for the past 20, 30 million years in primates as a general rule.
[00:09:00]	The issue here was that, as mass increases, you have a disproportionate increase in volume. They had this huge challenge. They didn’t want to sleep on the ground yet, because they’re not quite human yet, and they don’t have the kinds of defenses on the ground that modern humans have, even in forager and hunter-gatherer groups on the ground. They still wanted to stick in the trees, because they didn’t want to get eaten at night. They had to figure out a way to adapt around this ever-increasing mass, and I think the sleeping platform was this innovation.
Dan Pardi:	David, describe these platforms for us. What are they like?
David Samson:	I couldn’t possibly do a better description than Jane Goodall’s description going back to the 50s. It’s sort of an artifact of chimpanzee behavior. They weren’t even habituated yet at Gombe. She described them as, essentially the platforms had these frame-supporting branches. You find a crotch in the tree. On average, with chimps in east Africa, it’s around 12 meters, is the average in height. They’ll find crotches in the tree, and they’ll bend three to four branches back. Then they’ll create a weave, and so you have this basic frame, which is sort of like the box spring. Then, depending on what species, so for example orangs are particularly fastidious when it comes to this, even in the wild. They’ll go as far as 50 meters to find really plush foliage to make a pillow.
Dan Pardi:	Wow.
David Samson: [00:10:00]	Just to bring back to the nest they already made. Sometimes orangs, even more impressive, they’ll do double nests, where you have a platform on top of the platform that they’re sleeping on, just so they can stay out of the rain. Literally, this is primitive shelter.
Dan Pardi:	Interesting. Are there any differences in sleep for the primates that are sleeping on these platforms versus the primates that are not?
David Samson:	Yes. Yeah, great question. I did a direct comparison at the Indianapolis Zoo. Did a direct comparison between baboons and the orangs. The baboons at the zoo, we’d even introduce sleeping materials, the same sleeping materials that we did the orangs. The baboons completely ignored them. They didn’t once use them. Instead, they chose to sleep on their ischial callosities, which is essentially their butt pads. They huddled together. I was staring at 2000 hours of this infrared video for my dissertation, between both these species. It’s incredible. It’s like when you’re on an international flight, it’s the difference between first-class sleep and economy class.
[00:11:00]	The orangs are getting … They’re in these relaxed, souciant positions. They very rarely sleep together. In fact, only once throughout the entire study with the orangs were they within one meter proximity. They weren’t sleeping on the same platform. They built their own independent platforms. As to where with the baboons, they huddled together, and they’re not sleeping. Every once in a while, they’ll sleep on their sides, but mostly they’re sleeping on their butts, sleeping in an upright position. They’re huddled together, and when a high-ranking baboon breaks the huddle, everyone scatters. It’s like a domino effect. It’s the difference between sort of economy sleep, where you’re always upright, and this relaxed, first-class sleep that apes are privileged to have.
Dan Pardi:	Compared to the orangutans, the baboons sound like they sleep in a heightened state of readiness and therefore have more shallow sleep.
David Samson:         [00:12:00]	Absolutely. You’re hitting at an important point, is that to be in this state where your arousal threshold is lower you need to be in the first stages of non-REM sleep, so stage one and stage two. These are the lowest arousal thresholds. The really interesting, and the most important parts of sleep, from our perspective, the slow-wave sleep, that deep non-REM, and the REM sleep, that are attributed essentially to memory consolidation, attention, working memory, decision making, visual motor performance, cognitive control, emotion- all these things are attributed to slow-wave sleep and REM. This is the stuff you can’t get when you’re constantly in this light, non-REM stage sleep.
Dan Pardi:	Tell me if I’m wrong here. Their central nervous systems are adapted to maybe have adequate vigilance during the day with the shallow sleep. They’re not also doing the higher order cognitive processing that allows for more sophisticated cognitive thinking.
David Samson:	Precisely.
Dan Pardi:	Yeah, okay. There’s a clue for the evolutionary advantage for sleeping on these platforms and having the ability of deeper sleep.
David Samson:	Mm-hmm (affirmative). Yes.
Dan Pardi:	Nice. That makes a lot of sense. I’ll try another statement at this. These great apes that were able to create these platforms get deeper sleep. Potentially, this could have been part of the reasons why brains developed more past other types of primates.
David Samson: [00:13:00]	Yeah. This leads into that recent paper that Charlie and I published in Evolutionary Anthropology. We were shocked, actually. It was really surprising when we discovered that, if you do an analysis of every primate, of all the primate total sleep times, sleep quotas, non-REM, REM, that have yet to be published. When you do that analysis and you control for phylogeny, which is the evolutionary relatedness between species. When you control for phylogeny, humans actually have the least amount of total sleep time, yet we have the greatest proportion of REM jammed into that total sleep time. That was a really exciting discovery. I think it plays into this whole narrative that we’re developing right here, in terms of the advantages of human-type sleep relative to other primates.
Dan Pardi:         [00:14:00]	Okay, so we’re talking about the differences in depth of sleep amongst different primates and how that can possibly have been a contributing factor to the different cognitive capacities between us primates, but it makes me think of the executives and the students that are carving into their sleep time to get more hours in the day to do work, and how there’s probably some pretty serious consequences to that, given the importance of the sleep stages, slow-wave sleep and REM sleep in cognitive performance.
David Samson:	Absolutely.
Dan Pardi:	That’s a little bit of a softball question there.
David Samson:	Yeah.
Dan Pardi:	From that work, what are the next questions that you’re looking to evaluate further?
David Samson:	I think it’s an incredibly exciting time to be a sleep researcher. There’s been new advances in technology, in particular actigraphy, which allows us to be able to analyze sleep in dynamic field environments. Pre-industrial populations and in developing countries, places that simply were not represented in our sample of what is human sleep, before the advent of this technology. One of the things that we’re doing now is we’re working in a population in Madagascar in a remote village of Mandana in the Sava region of Madagascar. It’s a non-electric population. They’re small-scale agricultural population. It’s not fully developed, and it’s non-electric. We wanted to see what sleep looked like in this population.
[00:15:00]	I think this is a particularly important question because right now there’s a lot of attention drawn to this concept of first sleep and second sleep. I think in past podcasts, you’ve talked to different researchers that are interested in this question. Ekirch is a historian, and he saw this evidence in European literature of a first sleep and a second sleep, and even some evidence in equatorial populations of exhibiting this first sleep and second sleep. We wanted to tackle this question in this population, and look to see what their prevalence of napping was, what their prevalence of nighttime significant, biologically relevant nighttime wake bouts, or arousals, were at night. We wanted to be able to build that data set for comparisons to Western populations.
Dan Pardi:	David, I can’t wait to see what you find.
David Samson:       [00:16:00]	We’re pretty much ready to submit this work. I just gave a talk at the AAPA’s, it’s an anthropology conference in Atlanta. What we found is that they’re relying on segmented sleep a lot. It looks like they can be characterized as a population that has segmented sleep. For example, if you look at the averages across the entire city population of people that were engaging in the agricultural process. They’re going out into the fields every day, planting rice, and working in that small-scale agricultural capacity. Nine out of ten days, they nap, which is pretty crazy when in the West, in a recent publication, they did a large survey of Westerners, and they said that 46 percent of people reported in the survey reported two or more times that they nap per month. Our perception of what a lot of napping is is, I think, a little bit skewed compared to what other cultures across the world and across the globe consider is normal napping, even.
Dan Pardi:         [00:17:00]	I was a little surprised by Jerry Siegel’s findings from his 2015 paper in Current Biology. This is the paper that I interviewed him about in one of the first episodes of humanOS. You can go back, listener, and listen to that episode to hear more. Just as a reminder, he evaluated the sleep patterns of three different natural living communities; the Hadza, living in northern Tanzania, two degrees south of the Equator; the San people of Kalahari Desert, living 20 degrees south of the Equator; and then the Tsimane, that live close to the Maniqui River in Bolivia, which is about 15 degrees south of the Equator. One of the questions that he and his research team explored is whether these pre-industrial societies take naps.
David Samson:	Yes.
Dan Pardi:	I should say that the way that naps were recorded was by these people wearing actigraphs, which are watches that look at motion and light over a 24-hour period. These types of devices are really optimized to record nighttime sleep, not really daytime naps. They were still able to look at episodes during the day that they felt constituted the possibility of a nap. That means that typically there was just very little movement for at least 15 minutes. Then they would mark that as being a nap.
[00:18:00]	His team calculated that naps probably were occurring in around seven to ten percent of afternoons during the winter, and 22 percent of afternoons in the summer. He recognized that this method was probably overcapturing naps. In their estimate, he felt that naps were actually occurring with less frequency than what these figures suggest, possibly as low as three percent during the winter. If a nap did occur, the average nap length was about 32 minutes. That’s different from your findings and to me, what that suggests is that if both are right, then it shows that there’s a variety of ways in which Homo sapiens can sleep well.
[00:19:00]	One of those is to get a daily nap, and the other one is to have consolidated sleep at night. I don’t know if one is right and the other one is wrong. I’ve kind of come to the temporary conclusion that both seem to be possibilities for healthy sleep in humans. I’d like to just say that there was a lot of interesting things about his study. A couple that stand out is that hunter-gatherers don’t sleep more, compared to Westerners, but actually are on the lower end of the spectrum for sleep time. They didn’t go to bed when the sun goes down and wake up, as some have estimated. Rather, they would go to bed three to four hours after the sun went down, and they would wake up about an hour before sunrise. This sleep initiation and morning awakening were not correlated with light, but in fact changes in core body temperature.
	Speaking of temperature, but this time environmental temperature, I thought this was really interesting. If you think about how many modern humans sleep, they sleep in a temperature-controlled environment. It’s the same temperature across the night, and it’s possibly a temperature that is too high to allow the body to get into the depth of sleep needed for maximal sleep efficiency.
David Samson:	Absolutely. We’re just at the beginning of exploration in terms of these questions. I should say, the second, all that, I think it’s relating from the Madagascar data. We also found that their circadian amplitude, so the strength of their circadian rhythm, is actually much stronger than compared to Western population, which is a critical component. We’re disconnected from our environment, given the institutionalized shielding we have from it every day. This is a critical question.
Dan Pardi:   [00:20:00]	I suggest that people run a sleep experiment themselves, the purpose of which is to get in touch with what really good sleep feels like. You can get a lot of sleep in one night, and feel not so great the next day. I want people to run it for a couple weeks, really control light, environment, getting adequate daylight during the day, keeping lights very dim in the night. I recommend people get complete sleep, so what that means is not setting an alarm in the morning, but getting enough time in bed where you can wake up naturally, versus by an alarm. Running that for a few weeks, and seeing how you feel. If you can connect with a different feeling, then maybe that’ll motivate you to maintain good practices around your sleep habits.
	What I’ve noticed myself, to come back to what you were saying, is that when I am getting really good sleep, I notice much more robust alertness during the day. Then when I get sleep, I go from being alert, to when I’m sleepy, it’s like lights out. Then I think I get more deeper sleep, and I sleep more heavily. Recognizing that is good to connect with that feeling.
	I’m curious to know, for all the work you’ve done on sleep, how have you modified your own sleep habits?
David Samson: [00:21:00]	It’s interesting. When I first went to the University of Nevada in Las Vegas, this was my first academic position. I was a visiting assistant professor there. They had me teaching a four-four. A four-four is essentially four lectures, four different independent classes that you’re teaching per semester. This is double the national average. It was a lot of teaching. I was working 70-hour weeks. I was still getting publications out. I’d just been reading the literature on first sleep and second sleep, so I don’t know how conscious this was, but I ended up adopting a bi-phasic pattern, where I would do my double lecture in the morning and then take a good 45 minute to an hour power nap afterwards because I was so exhausted. I’m a pretty energetic lecturer, so I throw a lot into it, and then I usually end up being really tired afterwards.
	I would take an hour-long nap, and then I would drink coffee at 3 PM, and I would work until really late. I would usually sleep three hours, wake up a little bit more, read, work a little, and then go to sleep some more, and then repeat the process again. I felt like I naturally sort of took on a bi-phasic pattern during those days.
[00:22:00] Dan Pardi:	The author/blogger Tim Ferriss popularized something called polyphasic sleep several years back.
David Samson:	Yeah, yeah.
Dan Pardi:	Let me just describe what polyphasic sleep is. It is the idea of getting short bursts of naps to replace a longer consolidated sleep period. It was used in the military to help soldiers who didn’t have adequate time to get complete sleep do better on cognitive performance tasks, like flying planes, et cetera. This was interpreted to say, “Well, if you need eight hours per night, maybe we could reduce that to, let’s say four hours or less over the 24-hour period, by doing these short little naps.” A lot of people adopted it, but it’s problematic. Yes, you can do better if you’re only getting two or three hours of sleep by taking shorter naps here and there, but that doesn’t mean that you can reduce total sleep need by sleeping in this pattern. Side note: Here are two I wrote on polyphasic sleep (Article #1, PArticle #2) for Robbwolf.com.
David Samson:     [00:23:00]	I think this brings us back to what we were talking about with Gandhi Yetish and Jerome Siegel’s discovery of the traditional pre-industrial populations where they found they had more consolidated sleep. They didn’t see this sort of segmented pattern. From the data that we’ve got on Madagascar, we’re seeing this evidence for significant wake bouts. In fact, one out of every two nights there’s a significant wake bout in this population. It’s getting me thinking, and this is something I’m going to articulate in the publication, that perhaps it was once we began this quote-unquote “enforced work day.” Maybe that’s when putting demands, that sort of a top-down demand on human sleep-wake pattern, maybe this is somehow involved as well in the story and the narrative of segmented sleep.
	Hunter-gatherers, as a rule, don’t work that much. I think there was a study published that they work about 20 hours a week, if you look at their actual work hours. When they do it is on their own time. It may be that something very critical happened from the transition from the subsistence pattern that we’ve adopted for 99 percent of our species’ evolutionary history, the foraging, hunter-gathering subsistence pattern. There has to be some sort of consequence when we change to small-scale agriculture. There had to be some sort of eff ect on sleep and our sleep-wake pattern.
[00:24:00]	I think this is really an exciting time to be a sleep researcher, and to help probe these really interesting questions and have some critical predictions from these hypotheses that are getting out there now.
Dan Pardi:	A big part of what I do is trying to figure out how to optimize lifestyle to optimize productivity and performance. Some people recoil at the idea of trying to optimize productivity, because it feels like something that’s being forced upon them by an employer. The way I look at it is, the ability to actually enter into flow state more easily, to get done a task that you’re trying to do with efficiency. That means stepping away from your work when you’re feeling tired, being able to nap versus just trying to chug down another cup of coffee to modify- Not sitting in a chair all day, but actually standing, and thinking about how to augment blood flow to the brain and cognition, just through physical activity. We’re going to see a really big change in the way that we work over the next 20 to 15 years when the data supports better performance when you ease off a little bit of making somebody sit in a chair for 12 hours a day.
David Samson: [00:25:00]	Absolutely. In fact, I think that change, you’re saying 15, 20 years. I agree that it’ll really, in terms of our cultural norms, it’s going to change. Already, corporations are figuring this out. Google has these sleep pods now, where they basically are acknowledging that not everyone has the same chronobiology. Some of us are larks, some of us are owls. This trait is actually highly heritable. It’s up to 80 percent heritable. I think once corporations figure out that their employees are going to work better if you let them work when they feel like they’re going to need to work, or they can have the greatest optimization in their work, then they’re going to start making better bottom lines. Everyone’s happier.
Dan Pardi:               [00:26:00]	It’s funny, some of the companies that are really leading the way in terms of pushing technology, like Google and others, they’re the ones that are at the forefront of adopting these technologies for their employees, where I was thinking more kind of the mainstream adoption. Cultural adoption, where it’s actually normal for people to be able to say, “Okay, when do I work best? How do I schedule my day so that I can handle all the things in my life, get all my work done, as efficiently, effectively, and as best as possible?” That, I think, is going to take a little bit more time, but I’m excited to see that the conversation has started, that the research is looking at it specifically, that people are kind of evangelizing that it’s a topic that we should focus on. Hopefully, more and more people will have access to that flexibility to do it.
David Samson:	Yeah, I totally agree.
Dan Pardi:	Well, we are at 30 minutes here. Thank you so much for joining and sharing your work. Fascinating stuff. Definitely learned some really interesting things to augment my understanding of the evolutionary aspects of sleeping platforms and how that might have led to brain development. I’m really excited to read the next aspect of your work. Maybe we could bring you back on to talk about that when it’s published and you’re free to talk about it.
David Samson:	Absolutely. That would be great.
Dan Pardi:	Okay everybody. Thank you for listening to Human OS Radio. We’ll see you next time.
Speaker 3:	Thanks for listening, and come visit us soon at HumanOS.me.