Science Friday - Space Junk, Chronobiology, Mistletoe. Dec 20, 2019, Part 2

Episode Date: December 20, 2019

As more commercial companies are getting into the satellite launching game, space is becoming a crowded place and all of these objects are creating space debris. Right now, there are approximately 2,000 satellites floating in low-Earth orbit. Space agencies have estimated that are over 100 million small particles floating in low-Earth orbit, but there are no large scale projects to clean up these pieces of space trash.  Aerospace engineer Moriba Jah and space archeologist Alice Gorman talk about framing the idea of space as another ecosystem of Earth and what environmental, cultural and political issues come along with cleaning up our space junkyard.  Saturday’s Winter Solstice, which marks not just the arbitrary beginning of a season, but also the slow return of daylight to the Northern hemisphere. Or the coming decade, as many reflect back on everything that’s happened since 2010, and prepare to mark the beginning of 2020—a completely human invention. But there’s also an invisible timekeeper inside our cells, telling us when to sleep and when to wake. These are the clock genes, such as the period gene, which generates a protein known as PER that accumulates at night, and slowly disappears over the day, approximating a 24-hour cycle that drives other cellular machinery. This insight won its discoverers the 2017 Nobel Prize in Medicine and Physiology.  These clock genes don’t just say when you snooze: from the variability of our heart rates to the ebbs and flows of the immune system, we are ruled by circadian rhythms. Erik Herzog, who studies the growing field of chronobiology at Washington University in St. Louis, explains how circadian rhythms are increasingly linked to more than our holiday jet lag or winter blues, but also asthma, prenatal health, and beyond. And he explains why the growing movement to end Daylight Savings Time isn’t just about convenience, but also saving lives. This time of year, it’s not uncommon to see a little sprig of greenery hanging in someone’s doorway. It’s probably mistletoe, the holiday decoration that inspires paramours standing beneath it to kiss. But as it turns out, we may have miscast mistletoe as the most romantic plant of the Christmas season. In reality, the plant that prompts your lover’s kiss is actually a parasite. Ira talks with evolutionary biologist Josh Der about the myth and tradition behind the parasitic plant, and what it may be up to the other 11 months of the year.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. Later in the hour, we'll talk about circadian rhythms and the biology of time. But first, last month, SpaceX launched 60 satellites into low Earth orbit as part of its Starlink project, with Elon Musk's ambitious goal to provide satellite-based broadband. He'll need to launch 42,000 total satellites to complete the project. But each of those satellites is programmed to de-orbit and burn up in the atmosphere, and unless there is a problem then, the satellites will burn up in Earth's atmosphere

within one to five years. And you add to that the roughly 2,000 satellites already in low Earth orbit and, well, space is getting pretty crowded with our stuff, and all our stuff is creating a lot of junk. Estimates for the big pieces of trash, about 10 centimeters, that's about the size of your palm, about 20,000 of those objects.

The real tiny stuff, over a hundred million particles floating around above our heads. How can we clean up the planet's atmospheric attic and what questions should we be thinking about as more and more satellites and companies are getting into the game? My next guests are here to talk about that. Moribajai is an associate professor of aerospace engineering and engineering mechanics at the University of Texas at Austin.

Welcome to Science Friday. Hey, how's going, brother? Good to be here. Nice to have you. Alice Gorman is a space archaeologist, associate professor in the humanities arts and social sciences at Flinders University in Adelaide, South Australia. Her new book is called Dr. Space Junk v. the universe, archaeology, and the future. Welcome to Science Friday. Good to be here. Alex, I want to read from your book about just what is up there in space. You say orbiting Earth right now, satellites that work, satellites that work,

that don't work, the rocket stages that delivered them, bolts, canisters, faring, exploded fragments, flex of paint, shrapnel tools, fuel, and possibly a remnant or organic waste from human spaceflight missions. Yes, I mean space poo. Is there any way to keep track of all of this, Alice? Well, we have a whole range of different instruments on Earth who are actively tracking many of these space objects, but they tend to be the larger ones, the ones that are over 10 centimeters and they have to keep watching them

all the time because if they lose sight of them for a minute as it were, orbits are very non-linear and unpredictable, so things can get lost quite easily. So there's a whole bunch of stuff that we know where it is and there's a whole bunch of stuff that

we don't know where it is and another, millions and millions of all those tiny little things that are just too small to be. So we don't know where they are, and we need to predict and model all of this stuff to work out what the risks of collusion are, and we've just got massive gaps in the data that we have

about what's up there. More about most low-earth satellites and decommissioned space stations are programmed to fall back to Earth and burn up, right? What is creating, then, all of this debris if those satellites are supposed to burn up? Yeah, so, you know, interestingly enough, I think a good way to think about this stuff is that, you know, we don't put stuff in random orbits around the planet.

You know, we try to take advantage of mother nature of gravity as much as possible to spend the least amount of fuel. And as such, you can envision these kind of orbital highways in space. And they're very specific, depending on the kind of mission you have and what you want your satellites to do. So a lot of these satellites in low Earth orbit, even though you could just leave them by themselves, they would eventually reenter, but it takes a long time depending on the altitude. And I can tell you that things that are, I don't know, about 1,000 kilometers or so above the Earth surface won't be returning for several generations and even more. And so that is definitely a problem. So this idea of, well, things are programmed to come back. Things go wrong, you know, Murphy's law, so to speak, and you definitely need intent and purpose and hopefully, you know, everything working right to make that happen.

But even if you try to do that, then you have to figure out how do you avoid stuff on the way down? And that's another complicated issue. Yeah, let's talk about that a little later, but let's first talk about the mentality we have about Earth orbit. I mean, it seems like we just throw things up there and thinking about them coming down is like an afterthought, is it not? Well, so one of the interesting things is that I would say that is by and large seems to be the behavior that people have taken. At the United Nations level, there's this thing called the Office of Outer Space Activities in Vienna. And there's a committee on peaceful uses of outer space. And in fact, this calendar year, they just passed 21 guidelines towards long-term sustainability of near-Earth space.

But these things in and of themselves are not legally binding. They could be if each of the 93 countries that signed made them space law in their own country. But then it's like, well, how do you enforce that? What court of law do you bring stuff to? Like, there's a variety of issues and complications that follow. but implementing those would be kind of the next step. Alice, do you get the point I'm trying to make, and I think you make it in the book also,

that there's sort of this disconnect, that this is, well, it's not here on Earth, so it's not really that close to us. Yeah, so you think, well, usually we can't see any of this stuff. People on Earth are using all of these satellite services, but they don't sort of think or visualize or connect to everything that's over our heads. And in the space science community, I think, and the space industry community, it's pretty much like that.

Like you launch your space asset to do the job it's going to do. Once that job is done, you just don't think about it anymore. The calling it junk means in one sense you can forget about it and discount it in your planning, except, of course, as we now know, you absolutely cannot do that anymore. You mentioned in your book, and this was an interesting comment you make, you talk about when a big project happens on Earth, you put out an environmental impact statement. Do we need one for when we put something in orbit? I really think we do.

So at the moment, there's a whole bunch of things people have to do to get permission to orbit, put stuff into orbit. But because we're not really used to thinking of space as an environment, like for most people, people, space is a vacuum. There's nothing much up there. So we don't kind of have a much broader view of what all of the factors we need to take into account are. And the environmental management process basically involves taking into account impacts of all kinds, including social. And this is where I think we can connect with people on Earth who maybe don't normally think about satellites to maybe exert a bit of pressure on all of these big corporations and these big space agencies who have up until now been kind of pretty content to put stuff

up there and then just forget about it. So I think those social factors that come into environmental management are actually quite important. Well, what about, I'm sorry, Maura, but did you want to say something there? Yeah, so the thing that I wanted to follow up on that is that interestingly enough, you know, if you look at sustainability, I think first and foremost, people globally need to accept that near-earth space is a finite resource, and until that happens, we can't talk about environmental protection. So I think saying, yep, you know, outer space is probably infinite,

but near-ear-earth space is finite, and, you know, back to these, you know, specific orbital highways that are getting more and more congested with traffic. But once we can accept that, you know, near-space is a finite resource, Then we can talk about environmental protection. And one of the things that I'd like to underscore going to what Alice was saying in terms of bringing in the social piece is that if we look at models of sustainability on the planet, we can look no further than our indigenous people and what they've done to actually achieve sustainability. If you look at the Aborigines and the Maori in New Zealand and the Inuit in the Arctic, each of these indigenous peoples have for thousands of years developed, let's say a code of behavior, some norms and practices that have allowed them to be sustainable over thousands of years

and harsh environments and ecosystems of scarce resources. We should apply these tenets of, you know, so-called traditional ecological knowledge to achieve space sustainability. And this would allow people to be more inclusive and bring the sociological aspects that Alice was referring to. I'd just like to follow up on Moribar's point there as well because I think one of the issues is who owns space. You know, the situation in North Earth orbit has been called a tragedy of the commons. Space is meant to be the common heritage or province of humanity, but in fact a very few nations and corporations sort of have control of that.

So we need some different models of who can have access to space. and who can use it, that sort of blanket phrase common heritage isn't really sufficient at the moment. And picking up on what Moribah says, there are a lot of indigenous models of resource ownership. I don't mean ownership, resource use or resource responsibilities for resource, that I think we can also co-opt into being more creative about how we develop a sustainable long-term use of space. Our number is 8447-24-8255 if you would like to talk about this. This is a huge multicultural, multi-level problem. I know, Alice, you even talk about the value of the space, so-called junk,

where somebody's junk is someone else's treasure and actually using it as museum pieces up there. Well, there's some extraordinary objects. It's in that class of things that we just say, oh, you know, this is junk. There are some spacecraft that have incredible stories and that are connected to communities of people on Earth. And I don't think enough people know about this stuff. So I think we can look on it as not just on Othall, but not just as Moribus, as a limited resource

that we can use for our own ends to create, situation on Earth. It's a cultural resource as well. This is the junk up there is the story of the early space age. You know, 500 years from now, how are people going to look at some of these objects? They're going to be like a Paleolithic hand axe. They're going to be these extraordinary things that are a window into the minds of the people on Earth now who are, if you think about it, we're really only just starting to get into space. Alice Gorman, author of Dr. Space Junk versus the universe, archaeology in the future. Also, Morba Jha, we'll come back and take your questions, 844-8255.

Also, take your tweets at SciFri, so stay with us when we talk about more space junk after the break. This is Science Friday. I'm Ira Flato. We're talking this hour about space junk and how to clean up, live with it up there in low earth orbit. My guests are Muribajah, Associate Professor of Aerospace Engineering and Engineering Mechanics at U.T. Austin, Alice Gorman, author of the new book. It's called Dr. Space Junk v. the Universe, Archaeology, and the Future. Our number 844724-8255, let's go to the phones to Jeffrey in Cedar Rapids, Iowa. Hi, Jeffrey.

Hello. Hi, go ahead. Yeah, I was wondering if there's some way to sort of bring this more to. down to Earth in a sense that is there a website that we could go to where we could see the space depth so we could get a feeling for what kind of a mess we're making up there and kind of get a better hold on it. Good question. Alice, can you go see this? Is there a website to see what space junk looks like? There are places you can go to see visualizations of the density of space junk in its location. So there's some great images that NASA and ESA have. There's

also a database called Heavens Above that you can go in and look up any satellite and see where it is at the moment. And there are some great software things. One of them is ATK that will give you visualizations of space chunk in actual motion as it's going around the earth. But Moriba, you have your own one of these too, don't you? Yeah, so basically if you Google Astria, A-S-T-R-I-A, Astya-R-A-A-A-R-A-R-A-R-A-R-A-R-A-R-R-A-R-A-R-R-A-R-R-A-R-R-A-R-R-A-R-R-A-R-R-E-R-R-A-R-E-R-R-E-R-E-R-E-R-E-R-E-R-E-R-E-R-E-R-E-R-E-E-R-E-R-E- Facebook, Keith asks, is there any pollution or waste created when something burns up in the Earth's atmosphere? And if so, does the pollution stay in the Earth's atmosphere, or does it float off into space? That's a really great question. And in fact, some people have done studies

on rocket exhaust fumes from launches and their effect on the upper atmosphere. I haven't seen any studies on impacts of the re-entry of space junk, but Mariba might be aware of some of this research. Yeah, I mean, I can say that, you know, as objects are getting ablated and are dissolving in the Earth's atmosphere, certainly those particulates are part of the atmospheric constituents at those altitudes in terms of how long does it take those things to dissipate I'm not sure. I think here's the thing, right? Certainly it's not great.

I mean, you know, if you look at the oceans and what we've done there, you know, what happens if you take a one liter bottle of Coke and just dump it off the side of the ship? I mean, yes, eventually that gets diluted. But, you know, as you can see, if you do enough of that, then there's significant, you know, long-term impact of that sort of thing. Are we there yet? Probably not, but at the same time, it's something that we should be mindful of for sure. You know, the first thing that comes to mind when you ask people about what their reaction to this is like I do.

When they say, why can't we just take a net up there and just collect it all? You know, I'm sure, right, Alice, isn't that what people must be saying? It sounds like an easy thing to do. So that's what we'd do on Earth. We'd get some kind of garbage truck. We'd get containers. We'd gather it all up. The problem in space is that despite some of the visualized,

you'll see, things are actually quite far apart and they're moving at incredibly high speed. So you don't want to take your garbage truck or your net up there, have it collide with a piece of space junk explode and create more space junk. And at the moment with the propulsion systems that we have, it's actually really expensive to kind of maneuver around in orbit. You have to take all of your fuel with you. And the idea that it can just sort of zip around with your net or your heart. and catch all these things and bring them back.

It's just not possible at this point in time. You know, I think the greatest popular visualization we've had in recent years about what could happen in orbit with all the space junk is that movie Gravity where the space station is just trashed, right, by collisions with space junk. Is Mariba? Is that possible? Something like that? Yeah, so here's the thing, right?

I mean, yes, it's a bit of hyperbole in terms of this runaway process as accentuated as it was in the movie Gravity, but it's not out of the realm of the possible for some sort of cataclysmic event like that to happen with the space station. And we hope that never comes to that, but it's not out of the realm of the possible. And so this is something that we definitely have to be very careful of. And interestingly enough, you know, one of my good friends, former astronaut Susan Helms, she was telling me that, you know, there was this module in the space station that she would go in and she would hear these dings on the outer shell, you know, ding, ding, ding, ding, and it was fairly frequent. And, you know, guess what that was, space junk, whether it's micrometeeroids or actual fragments, you know,

flex of paint, that sort of stuff. So we know, we know that these things exist. We know that they're impacting different surfaces. We know that we face a tragedy of the commons unless we actually engage in sustainable behavior. A tweet from a forest who asks, what type of space junk is the most dangerous? Do you know there is actually, I was just going to say there's one object which is very dangerous, which is Envisat, which is kind of the number one old satellite on the top of

everybody's hit list. But that's one satellite, and then there are classes of objects which also have specific dangers. Let's go to the phones to Keith and Cape Coral, Florida. Hi, Keith. Hello. Go ahead. I had a comment about the newly formed space force and how that might affect the debris

in near orbit. Yes. Putting weapons up there, any ordnions up there, a mining space, and it has a lot of possibilities of experiencing the Kistler syndrome. Yeah, so I guess on my end, what I can say to try to address that as the following. In terms of weaponization of space and that sort of stuff, I can tell you, you know, having been part of the military myself and having worked for the Air Force Research Laboratory for a decade, nobody really wants to put weapons, as it were, in space.

I think everybody agrees that that's in general a really bad idea. As far as military presence in space, look, it's been up there since Sputnik. So the military of not just the U.S., but, you know, all these other nations, have been a part of space for a very long time. And I would say this, right? I mean, we have a booming space commerce landscape that is just growing by leaps and bounds. And I would say, you know,

when people needed to cross the oceans or they needed across the United States from the east coast to the west coast, sometimes, you know, the government would provide, call it escorts, you know, some sort of government presence to help protect the livelihood of these people going from point A to point B. My guess is, without currently working for the government, my guess is that it would make a lot of sense if the space force were analogous to the U.S. Coast Guard, that is there to protect the interests of the citizenry and

and enable space commerce. So in that sense, I think it probably makes quite a bit of sense. One last question. Really quickly regarding the whole Kessler syndrome, I have to tell you that I'm not a big fan of that concept. You know, everything that I've seen so far in nature is such that nature is always trying to seek some equilibrium state. And, you know, my guess is that at some point things become.

small enough to where it doesn't make that much of a difference. I need to interrupt because we only have about a minute left. One interesting tweet from Robin who says, what are your thoughts on the benefits of the global satellite internet versus the drawbacks of having thousands of SpaceX satellites obstructing our view of the celestial bodies and clogging up the Earth's orbital highway? And Alice, your last thoughts on that? Oh, well, I'm not a fan of Starlink.

Let's just put it like that. Okay. There's a good, succinct way to end it. Alice Gorman is author of Dr. Space Junk versus the universe, archaeology, and the future. Also, Mariba Jha, Associate Professor of Aerospace Engineering at the University of Texas at Austin. Thank you both for taking time to be with us today. Thank you. And you can read an excerpt from Dr. Gorman's book on our website at Science Friday.com slash space junk.

Next up, this time of the year, it's not uncommon to see little sprigs of greenery hanging in someone's doorway. It's probably mistletoe, the holiday decoration, and inspires paramours standing beneath it to kiss. But as it turns out, our notion of indoors during the Christmas season is a lot, well, cheery than the reality of mistletoe in the wild. You see, the plant that prompts that kiss is actually a parasite. I'm here to tell us more about this plant and what it's up to and other 11 months of the year. is my next guest, Josh Durr, Assistant Professor of Biological Sciences, Cal State Fullerton. Welcome to Science Friday. Thanks for having me.

Now, I consider myself a bit of a plant geek, but I was even surprised to hear about parasitic plants. I didn't know there was such a thing. Yeah, parasitic plants are fascinating. Tell us about what makes this plant a parasitic plant. What makes mistletoe a parasite? Well, so mistletoes attach onto the branches of other shrubs and trees, and they steal mostly water, but some also steal nutrients and sugars, and they rely on their hosts in order to complete their life cycle. They've got really specialized modified roots in order to help them attach and get into the host's vascular tissue. and they also have specialized dispersal mechanisms to get the seeds to the next tree.

You can imagine it's hard to get from one tree to another without some help. You know, you make this sound like it's a scary plant to be standing under. It's not really. These parasites do steal water and nutrients from their hosts, but they don't usually damage the trees enough to kill them unless the impasse. infestation is bad, and they're not going to really hurt you unless you eat them. A lot of them are poisonous. What other parasite plants might I be familiar with?

Well, the biggest flower is also a parasitic plant, reflesia. It's the corpse flower, and that grows inside of its whole. You may also be familiar with daughter, which is a parasitic plant that looks like orange silly string on shrubs. We also have root parasites that like sandalwood. So sandalwood is a parasitic plant, which weed. Let me just remind everybody that Amira Flato, this is Science Friday from WNYC Studios. And go to the question that I love to grow plants. I grow orchids and other kinds of plants, tough plants.

How tough would it be for me to grow my own mistletoe at home? It would be pretty challenging. You'd first need to have a suitable host. And once you've got a host, you'll need to establish an infection. And you can do that. You can put seeds of a mistletoe onto the branches of your tree. But mistletoe, at least the ones we use in our decorations, grow very slowly. They take several years to establish an infection.

And then if you're going to be harvesting it, you're going to not want to destroy the mistletoe by taking all of it. Right. Tell us how mistletoe got associated, this plant that you use the word infection associated with it because it's a parasite. How it could get involved with being a loving thing? If it's a parasite. Yeah, that's a great question. Mistletoe has a long history in mythology and lore. It's featured in stories from Norse mythology and Greek mythology,

and the druids revered it as a sacred plant. It traces its history as a Christmas decoration back to pagan rites in pre-Christian Europe. And it was one of the few green things available in the winter. And so people would bring it in as a reminder of spring. And it became associated with fertility. And for that reason, it is also used in that tradition you mentioned at the start of this segment, kissing under the mistletoe. How did you get started with studying mistletoe? It's not something I would think, you know.

You did your PhD thesis on this, did you not? I worked on mistletoes for my master's. But I was interested in mistletoes and parasitic plants because of their specialization and how they have this alternative life history of stealing resources, but also being really important ecologically. And so I've continued to work on it since getting my Ph.D. And I studied that. Did you find your favorite? Do you have a favorite one? Sure.

So I really like dwarf mistletoes. They have a very specialized seed dispersal mechanism where they launch their seeds out of the fruit, all on their own. and those seeds then attach into the host. And the mistletoe actually grows for several years inside of the host, much like an alien infesting someone. And when they're ready to reproduce, they burst out of the stem. And they've got these small, tiny flowers, and then they make their fruits and launch those fruits to the next tree.

Launch you pretty far, pretty fast. They can launch up to 30 meters or so. Have you ever seen one bursting out of the tree? I have. Sometimes when they're just right, you can like tap them a little bit and you can get them to launch the seats. Wow. No wonder you're so interested in it. It's fascinating.

I wish you good luck on your career studying mistletoe. Thank you. Josh Durr, assistant professor of biological sciences at Cal State of Fullerton. We're going to take a break and when we come back, you know, and depending on whom you ask, time is everything. Time is a flat circle. Time is just a figment of your imagination. Time doesn't exist. You name it. Someone has an opinion. But what the cells in your body say? The circadian clock and the biology of time will explore it.

We have time to do that when we come back after the break. Stay with us. This is Science Friday. I'm Ira Flato. Chances are you have many ways you keep track of time, right? You may be looking forward to tomorrow's solstice, the official start of winter. the slow return of daylight, or you may be thinking back on everything that's happened in the last decade as we prepare to enter the year 2020. And you may this very moment be looking at the clock and thinking about everything, you still have to get done before the sun sets and the day is done. But you know, there's another timekeeper that you can't see inside your cells,

telling you when to sleep, when to wake up. These are the clock genes, and they don't just say when you snooze, they determine your heart rate, hormones, we're ruled by circadian rhythms. There are cycles under scrutiny in the field of chronobiology. Yes, and my next guests say a better understanding of the clock genes might help us with more than our holiday jet lag.

There are whole frontiers in health opening up as research and time march on, so let me introduce my guest. Dr. Eric Herzog, professor of biology at Washington University in St. Louis, President of the Society for Research on Biological Rhythms. Welcome to Science Friday. Hi, Ira. Thanks for having me. You're welcome. You know, I think it's probably new to everybody that there's a gene that keeps track of time of day.

That's right. There's a handful of genes that we call clock genes that we say are essential for scheduling our day. And how does that work? What's going on there? Well, inside individual cells in our body, there are 19,000 genes, a subset of which are expressed in any given cell type. And of those expressed genes, there's a handful that are really responsible for keeping near 24-hour time for those cells. So these are genes we call clock genes because when they're mutated or messed up, the cells lose their ability to keep near 24-hour time. The way the clock works is something we call the TTFL or the transcription translation feedback loop,

where a clock gene is turned on and it makes its message. That message then gets turned into its protein. Those proteins accumulate to a critical level, and then they go back into the nucleus of the cell to turn off the transcription of that clock gene. With that repression, the gene then turns off, the messages go away, the proteins go away, And about 24 hours later, the repression goes away and the gene can start expressing itself again. So this internal, intracellular clock can keep near 24-hour time in just about every cell in our body. So if each cell in our body has one of these timekeepers, are they all synced together?

Because if they're not, wouldn't you have chaos? Yeah, exactly. So to be a good rhythmic person sleeping at night, awake during the day, having hormones like cortisol rise just before we wake up, melatonin rise as we go to bed, we need to have a coherent rhythm amongst all of these cells. All the cells need to agree on what is local time. They need to be synchronized to each other. And how does that happen? So synchrony seems to be mediated. The action. is all in our brain. There's a teeny tiny spot in the base of our hypothalamus right on top of where our optic nerves cross. So if you follow your eyes back into your brain, sitting right

on top of where your optic nerves would cross, is a spot that's about a millimeter by a millimeter by a millimeter called the supra-chaismatic nucleus, the SCN, meaning sitting on top of the optic nerve crossing. And that spot is comprised of about 10,000 neurons on the the left side of the brain, 10,000 neurons on the right side of the brain in the base of the hypothalamus. And that acts sort of like the atomic clock, which synchronizes the clock in all of our alarm clocks and computers. It's the atomic clock for our body. It is responsible for sending out timing signals to the brain and body to keep us as a coherent orchestra of clocks.

Now, we always hear about the, that you depend on sunlight. to sort of reset that clock. Is that why the optic nerve where your eyes are connected to that to know that there's light out there? Exactly. So light enters through our eyes, and it stimulates our rods and cones, the photoreceptors in our eye,

but it also stimulates another population of photoreceptor cells that were really only recently discovered. It's pretty amazing that we've known all the cell types in the retina basically since 1865, but within the last 20 years, It was a new photoreceptor that was identified called a melanopsin cell. It expresses a special pigment called melanopsin. And those cells are the ones that actually project down your optic nerve and make synapses or connections in the body clock, the SCN,

to communicate when it's day and when it's night to synchronize your body clock to the local light, dark cycle. And the biggest 24-hour cycle most of us think about, of course, is sleeping. what about this process determines our sleep schedule? So the master clock in the SCN is intriguing in that it's the same in diurnal and nocturnal organisms. It's metabolically active during the day and relatively quiescent at night. But it's sending out signals to different parts of the brain, we think, that are interpreted as now it's time for you to sleep. And those signals include regulating things like the hormone, melatonin, which is secreted by your pineal gland, and is a signal that helps to promote the onset

of sleep. So what happens when you have a night owl or somebody who's sleep, you know, doesn't go to bed before midnight, something like that? Does that upset the sleep center in the brain or the release of melatonin? What's out of sync with that? Great. So first, I think it's important for us to say that it can't. be perfectly normal and healthy to be a night owl, to be a late bird or an extreme early bird.

There's natural variation amongst all of us, and at least some of that variation can be explained by variation in our clock genes. So there's really beautiful work, for example, on one of our clock genes called the period two gene, showing that different mutations in that gene can turn you into either an extreme early bird or an extreme late bird. just changes in the sequence of that one gene, change how fast your clock runs. And if your clock runs with a short period, less than 24 hours,

you tend to be an early bird. If your clock runs with a long period, longer than 24 hours, you tend to be a late bird, a night owl. So at least part of the difference between all of us who prefer to wake up either early or late can be explained by our genetics.

But that's not the whole story. That's interesting because, you know, We attempt to think of, well, I'm abnormal because I'm an early bird or a labor, but you're absolutely normally. You just have variable genes that are doing it for you. The winter solstice is upon us, and for many of us in the Northern Hemisphere, that means going to start seeing more daylight soon, though at least one listener is not excited by this.

He's Mark from Wisconsin on our Science Friday Voxpop app. I think I might be an outlier, but I actually prefer the shorter days and longer nights. I like the cold weather, and I sleep a lot better when the night is really long. During the summer, I have trouble sleeping. It's hard to go to bed when it's light out and get up when it's light out. Eric Herzegner, does that mean he has maybe a genetic variation to the norm? No, in fact, we, like many of the animals on this planet, are seasonal creatures. So many of us will describe feeling differently in the summer than we do in the winter.

Personal preference aside, I think it's important for us to appreciate that lots of creatures on this planet are seasonal breeders, for example. They adjust to the long days by actually changes in their circadian system. So the circadian cells in our body are adjusting their relationship to each other to say it's summer compared to now as winter is coming. These cells are changing their relationship to each other to help us adapt to these season. challenges. And in the extreme, this clock can be related to things like hibernation and migration. Let's go to the phones because we have a couple of interesting calls. I want to get to Elizabeth in Woodland, California. Hi, Elizabeth. Hi, I love your show. Happy New Year and all. Thank you, too.

Anyway, I'm calling about, he said light affects the brain. I have three questions. One, how does jet lag work when you're going, you know, across the world? or daylight savings. I have friends who say one hour makes a major difference. Or what about light for people in northern regions where you have six months sun and six months not? Okay, happy new year to you too. What do you say, Eric? Those are three fantastic questions.

The first question about how does light affect the brain. We think that it's sending signals to indicate when dawn and dusk are occurring locally. So when we travel across time zones and we are suddenly challenged with the sun is coming up, let's say, six hours early because we just flew from St. Louis to Paris. We have not yet adapted to be able to adjust to that big change. We're a species, just like every other species on the planet that's had to experience small changes in day length, like a minute or two each day. But now, with the ability to fly across time zones over the last hundred years or so, we are challenged to be able to shift our clock much bigger shifts, many more hours. And so we're going to try and make our clock wake up six hours earlier when we fly east.

And that's why we feel jet lag. The clock, the internal clock system, is not able to make that shift completely in one day. And what we feel is sort of an internal desynchronization, the clocks in our body. are not synchronized to each other and to local time, and until they get on local time, we can actually feel a form of depression, getting back to the caller from Wisconsin, how this clock system can really affect how you feel. Let me go beyond our discussion about sleep, though. There's been research on how we eat and circadian rhythms, and I'm thinking of a recent

clinical study finding that eating within a 10-hour window could stave off diabetes, heart disease, other problems? Are you familiar with that? And why would that work that way? Yeah, this is a really beautiful study from Dr. Sachin Ponda's lab and his colleagues at the Salk Institute. In that study, they asked whether just restricting your eating hours to 10 hours of your waking period would have any effect on your body weight. And this particular study was on people who have metabolic syndrome, so they have trouble processing food. And what he showed was that they could actually better manage the digestion of that food. They actually lost weight. They were able to stave off some of the symptoms of diabetes by just eating at the right time of day. So we like to say it's not

just what you eat, but it's also when you eat. And how that works is something that's really still being actively studied, but I'd like you to think about it like this. You have evolved to eat during your waking periods and starve all night long while you're sleeping. And so your body has adapted to move the sugars around from when you're eating to processing those sugars to keep you going while you're sleeping. And maybe an easy example is thinking about a plant which has to photosynthesize in the light and then starve all night long in the dark. That's quite interesting.

Our number 844-724-8255. I'm Ira Plato. This is a Science Friday from WNYC Studios. Are there other medical applications to our understanding of circadian cycles besides just talking about when we eat? Yeah, it's really an exciting time for the field of circadian biology or chronomy biology. Two years ago, three scientists in the field won the Nobel Prize for their discoveries of the molecular basis for how these rhythms get started. And I think in part they won the Nobel Prize in medicine or physiology because this really beautiful intracellular clock seems to be regulating so many aspects of our biology and our health. So there's a very active area of biology that's being applied to medicine called chronomedicine, where, for example, drugs can be delivered at particular times of day to get better results.

And nice examples of this are asthma medications that are designed to be slow release during the night and act while we're sleeping when asthma attacks are more frequent. Or drugs that are used to treat heart disease and protect us against the increased risk of heart attacks just before we wake up in the morning. My lab is actually in collaboration with two oncologists here at Washington University. And we're studying the potential of a drug that's being used. in treating brain cancers, glioblastoma. And we've shown that that drug is actually much more effective at killing the cancer at one time of day compared to other times of the day. That's interesting.

Another fun... Yeah, go ahead. Yeah, one other fun example that I've really become very excited about is we have an ongoing collaboration here at Washington University with folks in the obstetrics and gynecology, where we're asking whether the risk for preterm birth, might be associated with disruption of circadian rhythms. So we've been following 1,200 women here in St. Louis with funding from the March of Dimes

to ask whether their daily schedules are associated with their risk for delivering preterm. That's interesting. So if you look to make use of this knowledge, what can you learn that could help us or make us healthier from your research? So I think the first thing that folks in the field would like everybody to think about is throwing away your alarm clock.

If this biological clock is there to tell you when to wake up and go to sleep, and every time we use an alarm clock, we're waking up unnaturally, if we could just listen to our body clock, that probably would be a good step in moving towards a healthy lifestyle. The applications of this in terms of things like when schools should start are obvious, and Many people in our field are really working to start high schools a little bit later than they currently are so that kids can wake up naturally instead of by alarm clocks. We're thinking a lot about lighting scenarios in medical settings, like improving the lighting in hospitals. Dr. John Hoganesh in Cincinnati has worked really hard to help the hospitals there. Think about best lighting conditions for the patients and for the clinicians.

Fascinating. I want to thank you. Wow, thank you for taking time to be with us today, Dr. Herzog. It's my pleasure. And time as they say flies, so I want to say goodbye. I'm sure you're tired of hearing time jokes by now. Dr. Eric Herzog, Professor of Biology at Washington University in St. Louis and resident of the Society for Research on Biological Rhythms. Just a reminder, a Science Friday Voxpop app, we want to hear from you, especially from all you,

bird nerds. If you're outdoors and you're participating in this year's Christmas bird count, we want to know what you're seeing and what you're hearing. If the bird you see makes a sound, please record it for us and send it to us. Just don't forget to tell us what it is and where you saw and who you are. You can go to our Science Friday Vox Pop app wherever you get the app. It's our Christmas bird count. We do it every year. We'll be doing it this year. And maybe we can get you, your bird and your sound in there on our next show. So go to Science Friday Voxpop app and recorded for us. And of course, we're active all day, all week on social media, Facebook, Twitter, Instagram, email us if you'd like also. And have a great holiday season. We'll be

seeing it after, well, before New Year's, but after Christmas and Hanukkah. So stay with us and have a happy holiday all season long. I'm Ira Flato in New York.