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Studying The Biological Clock


Scientists at UC San Diego studying the biological clocks of bacteria, fungi, plants and animals have joined forces to apply their knowledge across these diverse groups of organisms to human sleep disorders in a newly established Center for Chronobiology.

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UCSD Center for Chronobiology will host a chronobiology symposium March 10-12, 2010

MAUREEN CAVANAUGH (Host): There are certain cycles hardwired into human beings, but modern life messes around with them. We have certain rhythms about eating and, especially sleeping that don't always coincide with a 24/7 lifestyle. In fact, we're just about to shake up our sleep cycle this weekend as we spring forward to Daylight Saving Time. As it turns out, human beings are not the only living things with rhythm. And a newly established center at UC San Diego is using research into the biological clocks of other species, mice, frogs, plants and bacteria to unlock the mysteries of these rhythms and help us all get back in sync with our bodies. I’d like to welcome my guests. Dr. Steve Kay is Dean of Biological Sciences at UC San Diego. Dr. Kay, welcome to These Days.

DR. STEVE KEY (Dean of Biological Sciences, University of California San Diego): It’s great to be here.

CAVANAUGH: Dr. Susan Golden is co-director of the Center on Chronobiology. Dr. Golden, welcome.

DR. SUSAN GOLDEN (Co-director, Center for Chronobiology, University of California San Diego): Good morning.

CAVANAUGH: And Dr. Sara Mednick is here. She’s assistant professor in the Department of Psychiatry at UC San Diego and author of “Take a Nap! Change Your Life.” Dr. Mednick, welcome.

DR. SARA MEDNICK (Assistant Professor, Department of Psychiatry, University of California San Diego): Hi. Thanks for having me.

CAVANAUGH: And we’d like to invite our audience to join the conversation. Do you have questions about your sleeping or eating cycles? Do you have a story to share about how a trip or a different work schedule disrupted your life? Give us a call with your questions and your comments, 1-888-895-5727. So, Dr. Golden, what is chronobiology?

DR. GOLDEN: Chronobiology is the study of biological timing, so a vast array of different kinds of organisms have internal biological clocks that can keep track of the time of day and the seasons of the year. And chronobiology is the – covers all kinds of research on different organisms that are related to these internal biological clocks.

CAVANAUGH: Could you give us an idea on how these internal biological clocks affect our daily life?

DR. GOLDEN: Yes. The way that most people realize that they have an internal clock is when things go wrong, and usually that’s – most obviously it’s when you get on a plane and you travel several time zones and you find out that you’re not feeling like eating at the right time and you’re not sleeping at the right time of day for your schedule and what works in with your business and social schedule. And that’s because your biological schedule has not reset. And we tend to think that we do what we do because the environments change. We wake up when the sun comes up and we go to sleep when the sun – after the sun is down, but really the sun coming up and going down is setting an internal clock and it’s the clock that our body listens to, not – much more than those cues that are coming in externally.

CAVANAUGH: Oh, that’s interesting. So, in other words, if everything’s going great with our biological clocks, we don’t notice them. It’s only when they go off kilter…

DR. GOLDEN: That’s right.

CAVANAUGH: …that we have a problem with them. Now, you’ve taken, with this Chronobiology Center, a unique approach. It’s a collaborative approach among scientists who perhaps wouldn’t normally work together on this idea of circadian rhythms and biological clocks but they’re all in this new Chronobiology Center. Tell us a little bit about that approach.

DR. GOLDEN: The center includes 24 faculty who are in different departments and divisions across the university from people who study sleep, like Dr. Mednick, who’s here today, and at the very opposite extreme, I guess would be me. I work on bacteria and do biochemistry and molecular biology work, so everything from clinical work to this very basic science on model organisms including microorganisms. And this is just an amazing array of faculty that really represent almost every kind of work you can do in chronobiology, and we’re all here in one place and the center recognizes that amazing focus and breadth and depth of research and tries to bring people together so we start talking to each other more and finding out what we can do together that lets us ask – tackle more difficult problems and answer bigger questions.

CAVANAUGH: I understand UC San Diego has among the largest groups of people working in this field on any campus, is that right?

DR. GOLDEN: I’m not aware of any place in the world that can touch us in terms of having this many people all in one place focused on chronobiology and, in particular, on different kinds of chronobiology, so we really represent different facets of the field as well.

CAVANAUGH: Dr. Kay, I’m wondering, how do you think this collaboration will help the research process?

DR. KAY: Well, these days, modern science approaches very complex problems and so something like understanding how clocks are built inside of cells, asking questions about how clocks affect our daily lives, we would, of course, love to approach all of these questions ultimately in human beings but really we can’t start there. And so the work that Dr. Golden does in bacteria is very relevant to understanding how do you build a clock inside of a cell. We literally have to become watchmakers where we’re going to take off the back of some very beautifully crafted Swiss watch and try to figure out how it works. And so by looking at a fruit fly or looking at a mouse or also looking at a plant, we can really get an idea of what the cogs are of the biological clock and that will tell us, ultimately, what happens when clocks go wrong.

CAVANAUGH: I’m wondering, Dr. Kay, does every living organism have a biological clock of some sort?

DR. KAY: The answer essentially is yes. There are swaths of some types of microorganisms that don’t appear to have clocks but in general everywhere we look, we find these 24-hour circadian clocks that we’re talking about and, of course, that tells us that these clocks are fundamentally important to us because it really looks like they’ve been either preserved throughout evolution or they may have even have arisen multiple times during the course of evolution.

CAVANAUGH: And I think since we’ve mentioned it a couple of times, could you define circadian rhythm for us?

DR. KAY: Yes. I mean, there’s many types of biological timing events and the ones that we’re most interested occur on the 24-hour basis, and so that really is what circadian rhythm, circa diem, about a day, it’s all of these rhythms in our physiology, our metabolism, our sleep-wake cycle, that relate to the Earth turning on its axis and having these alternate periods of light and darkness on a 24-hour scale.

CAVANAUGH: I’m speaking with Dr. Steven Kay. He’s Dean of Biological Sciences at UC San Diego. I spoke with Dr. Susan Golden, co-director of the Center of Chronobiology. And I’d like to get Dr. Sara Mednick into the conversation. She’s assistant professor in the Department of Psychiatry at UC San Diego and author of "Take a Nap! Change Your Life." And, Sara, what’s the relationship between the larger issue of chronobiology, the biological clock, and human sleep disorders?

DR. MEDNICK: Well, I specifically look at sort of not necessarily disorders but just normal sleep and normal cognition across the day and across the night. And my main interest in being part of the center is actually that, you know, I think the scientists kind of become a little entrenched in their world view and in what it is that they’re studying and so I always study sleep and cognition. And so the center allows me to branch over to people who are actually doing more circadian rhythms things and looking at light and the effect of light on entrainment to – or how light effects our abilities to be awake or alert during different times of the day. And that’s very important actually when you’re looking at cognition across the day, so I look at daytime sleep and how daytime sleep can affect memory and learning and, obviously, things don’t – well, not obviously. But things are not the same across the day; we actually have shifts in our cognition across the day and some of that has to do with our circadian rhythm is that we have these little dips in – we have an increase in our cognition across the day that we get better and better and better but at the same time, right in the middle of the day, right when you’re supposed to have a siesta, you actually have a dip in your cognition and you have a dip in your core body temperature. And these are all things that are given to us, these bits of information, from more circadian rhythms kind of research. And so being able to put these things together – right now, I’m working with Michael Gorman, who’s also part of the center, looking at how light effects daytime sleep as opposed to just being able to think that we don’t have any effects of our external environment on our circadian rhythms or our sleep.

CAVANAUGH: We’re talking about the new Center for Chronobiology at UC San Diego and we’re taking your calls at 1-888-895-5727. Let’s take a call right now from Max in Encinitas. Good morning, Max. Welcome to These Days. Oh, dear. Cannot hear Max. We’ll have to go back and see if we can talk to Max in a little while. You know, I understand, Dr. Mednick, that you don’t deal so much with disorders and so forth but, you know, people with problems with sleep are just – I mean, that’s endemic. Do you have any idea how many people suffer from sleep disorders?

DR. MEDNICK: It’s a huge amount. I’m not exactly sure if we know what the numbers are but we do know that it’s – if you look at sort of the cost of sleep deprivation and the cost of sleep disorders, it’s something about $150 billion a year that is spent on either clinical issues or just sleep loss related accidents, so it’s a huge amount and it’s clearly, if you look at the way the pharmaceutical industry has kind of honed in on sleep pills, you can see that people are really trying to find ways to deal with their sleep problems that are not just through natural ways but they’re any way that they can. So it’s clearly a big issue.

CAVANAUGH: We know about the pills. Are there any other common therapies that are used to try to get people back on a normal rhythm when it comes to sleep?

DR. MEDNICK: Yeah, the best actually, I think the strongest is through light therapy so people actually are supposed to sit in front of these large light boxes right when they wake up and sit there and have their eyes really exposed to the light for about 30 minutes right when they’re waking up because light is such a strong – it’s called a zeitgeber and what that means is it’s just a time giver. So we have all these external cues as well as those internal cues and the external cues, the strongest one is light. And so if you have a problem with your circadian rhythm and you can’t seem to get used to being awake during the day, to sleep at night, light therapy can be the strongest way of changing your rhythm.

CAVANAUGH: Let’s try Max again from Encinitas. Good morning, Max. Welcome to These Days.

MAX (Caller, Encinitas): Good morning. Thank you. My question involved jet lag. I periodically travel to Asia and it seems like when I travel to Asia, I’m more or less fine, you know, within a day or so of getting there. But when I come home, I’m messed up for sometimes up to a week from jet lag as far as sleep schedules and – And I’ve heard from people that traveling from east to west is often worse as far as jet lag and I was just wondering if there’s any clinical evidence of that or why that might be and I can take my answer off the air. Thanks.

CAVANAUGH: And, Dr. Mednick, any reason why going to or from would be worse when it comes to jet lag?

DR. MEDNICK: Yeah, I think that he’s actually right, that I’ve always heard that going from west to east is much more difficult to adapt to than east to west, and I’m not exactly sure as to why that might be. It might be that just waking up to the sun faster – or, earlier might actually entrain your system easier rather than having to wake up later to the sun, so advancing your sleep phase versus delaying your sleep phase but that’s a little technical. But what’s interesting is there are differences across people that some people actually are more – they suffer more when they go west or they suffer more when they go east and this is – I don’t really think that we understand why that is and it’s, you know, there’s all different sorts of ways that you can attack this issue sort of, you know, should you be getting used to the sleep that you’re going to be having a little bit earlier and actually change your sleep times earlier than your actual trip? Or then, you know, or napping during the day so there’s many different kinds of variables as to how you can manipulate these things.


DR. KAY: Yes, there is a difference traveling east/west versus west/east and it’s basically to do with how our circadian clocks can be bumped.


DR. KAY: So if you think of our clock in our brain as a clock that’s on the wall, what light-dark cycles do is to bump the hands of that clock each day. So, really, one of the best ways in which you can adapt to a new time zone is to try and expose yourself to light when it would’ve been the early evening in your previous time zone. So, for example, you know, if your time zone is San Diego and you’re on a business trip to either Europe or over to Japan, then what you really need to figure out is when is it early evening in San Diego and try to get yourself in front of a bright light source for 20 to 30 minutes.

CAVANAUGH: And Dr. Golden.

DR. GOLDEN: One of the other interesting things that’s come out of the field in the last five years or so is that even though we really focus on sleep-wake with respect to jet lag, there are a lot of other internal clocks around the body that don’t actually respond to light and dark, they respond to our metabolism. And feeding at the appropriate time can be important. So part of the reason that you feel lousy when you’re jet lagged, it’s not just that you are sleep deprived but also that blood pressure, heart rate, the enzymes that are important for digesting your food, these are all no longer coordinated. And so in addition to getting your sleep on track, it’s not all about light, some of it’s about food.

CAVANAUGH: That’s fascinating. So it’s not just all about sleep and light, you’re actually really deeply messed up.

DR. GOLDEN: You’re very deeply messed up, and completely uncoordinated. I mean, everything in your body has gotten out of whack so clocks that should all be aligned and should be set to the same time zone are all on different time zones.

CAVANAUGH: We have to take a short break, and when we return we’ll continue to talk about the new Center for Chronobiology at the UC San Diego campus and take your phone calls. You’re listening to These Days on KPBS.

CAVANAUGH: I'm Maureen Cavanaugh. You're listening to These Days on KPBS. We’re talking about the new Center for Chronobiology, studying the rhythms, the daily rhythms of humans as well as other species, mice, frogs, plants and bacteria, and what we can learn about that to unlock the mysteries of these rhythms. I’m speaking with Dr. Steven (sic) Kay. He’s Dean of Biological Sciences at UCSD, and Dr. Susan Golden, who is co-director of the Center of Chronobiology, and Dr. Sara Mednick is assistant professor at the UC San Diego Department of Psychiatry and author of "Take a Nap! Change Your Life." We’re taking your calls at 1-888-895-5727. We ended on a very fascinating note about the idea of jet lag sort of not only disturbing sleep rhythms but other rhythms in the body. And, Dr. Kay, I’d like to talk about how this might also affect people who work in shift work, who work at odd hours of the day. Are their rhythms also chronically disrupted?

DR. KAY: Yes, and there’s an increasing number of large scale studies now coming into the literature that are pointing to the fact that people who are subject to chronic shift work, essentially what’s happening is your body clock is still running but our body is essentially a symphony of clocks and if those different components of the symphony aren’t all playing in time together, it can lead to illness. So what you find in shift workers is an increased susceptibility to obesity and diabetes, increased cardiovascular problems and even increased cases of cancer. And each one of those biological processes is actually tied to our clocks, our blood pressure, for example, is very closely clock regulated, our liver metabolism. And how we deal with food and glucose is clock regulated. And so there is a mounting body of evidence that is showing that the inability in shift workers for their clocks to be correctly coordinated can lead to several types of chronic disease.

CAVANAUGH: I wonder, Dr. Golden, in this new Center for Chronobiology, as you’re going to be studying so many different species, you, yourself, study bacteria, is there any link that we’ve found connecting the biological clocks, these symphony of clocks, that Dr. Kay was talking about, between humans and other species?

DR. GOLDEN: Well, I think that one of the things that the bacterial system has shown us is that there are things we hadn’t imagined before, just looking at plants and animals. And so the bacterial clock does seem to be different than the clock in humans, at least everything we know about the clock so far in humans. And – But that’s actually informing us of things. So, for example, I mentioned that in humans feeding and metabolism is important. We’re finding out in the bacteria that that metabolism seems to be how they set their clocks and so we’re getting information from that. One thing I – as a proponent of bacteria, one thing that I need to point out is that humans actually aren’t the only important organisms on the planet. I work on a kind of bacterium called the cyanobacterium and right now they’re making 30% of the oxygen that we’re breathing. They’re very important to the planet, and understanding their biology is actually just as important as directly understanding the biology of humans.

CAVANAUGH: Do you know enough now about the rhythms in that form of bacteria to be able to disrupt them and, therefore, study how the bacteria copes with its own form of jet lag?

DR. GOLDEN: Absolutely. We have – Yes, we have mutant bacteria that have jet lag. We’re learning a lot about them. And we’re – one of the really nice things about the bacterial system is that we do have the opportunity to do what Dr. Kay said, which is to take the back off of this Swiss watch and understand its components. So we understand its components in very great detail and that’s much easier to do in a bacterium that has fewer genes and its cells are set up more simply and we’ve been able to learn a lot about how it works and how it controls processes in the cell.

CAVANAUGH: And let’s take a phone call. We are taking your calls at 1-888-895-5727. David is calling us from Hillcrest. Good morning, David. Welcome to These Days.

DAVID (Caller, Hillcrest): Good morning. Thank you for taking my call. I was – in your discussion regarding circadian rhythms, it seems that you have indicated a natural basis for a 24-hour human biological cycle and it seems to me, I recall, many years ago studies where they put people down in caves for extended periods of time without any light cues or time cues to observe how that might affect their natural cycle. And I’ve heard, and I could be wrong, this was quite some time ago but I seem to recall them talking about, you know, these cycles that, you know, stretching out to as long as perhaps 36 hours. And I was just curious whether or not this is – am I remembering correctly or has this been discredited and so forth? So I’ll just take my answer off the air. Thanks.

CAVANAUGH: Thank you, David. And, Dr. Kay, would you like to address that?

DR. KAY: Yes, David, a lot of studies on humans have done exactly what you’ve said, which is to take human volunteers and to find out how their clocks tick to put them into isolation. And so what you’re doing is taking away the conductor’s baton from the symphony and just then looking at how all these instruments play out on their own. And what that really reveals is the endogenous pace, the internal pacemaker. And what we find from that is that each human differs slightly in how fast their clock runs in the absence of cues. And I think in modern studies we’ve found that you don’t find humans with such long clocks as you’ve talked about like 30-odd hours, that would be quite rare. But for many human beings, our clock might be half an hour or an hour longer than 24 hours. And the great thing is, is that our clocks don’t have to be exactly 24 hours because we can take dawn and dusk and reset our clocks each day. But each one of us has a chronotype, the length of our clock is a little bit different when measured in isolation and that can relate basically to whether we’re night owls or larks, the so-called morningness and eveningness. There is this new term now called chronotype, what chronotype are you?


DR. KAY: Are you a morning person or an evening person? And that also will relate to how long our clock is when we measure it in isolation.

CAVANAUGH: Well, that goes, Dr. Mednick, to the issue of how much sleep do we need. Does it differ from person to person always?

DR. MEDNICK: Yeah, there’s a huge variety in sleep need. You can have people who are called short sleepers who can actually just go back – get by on five hours a night and versus people who are long sleepers, who need 10 to 11 hours at night. And then there’s sort of a range right in between. For the most part, people around seven and a half hours, they survive perfectly fine with seven and a half to 8 hours at night. But the range probably has some genetic components. There’s a recent study that looked at two family members that both showed the same genetic components to have short sleep, so there does seem to be some genetic components but also, you know, there probably is also some social components to how a family is raised, whether they raise each other on being short sleepers or long sleepers.

CAVANAUGH: I remember a news article about research a while ago that said, if I recall it correctly, that people sort of underestimate the amount of sleep that they actually need though. They might tell people, oh, I’m fine on six hours but you can see if you study them as they go along that that’s not really true. Do you remember what I’m talking about?

DR. MEDNICK: Well, that’s especially true for doctors. If you ever hear doctors saying whether they actually need to get seven to eight hours of sleep, most of them will say that they are somehow special, and it’s just true for the whole medical community that they don’t really need to get enough sleep and that they’re able to work fine, especially if they have these high stress environments. I’m not exactly sure of the study that you’re talking about but it’s very true across many different kinds of groups. And what’s interesting is when you actually experimentally study these groups and you don’t let them know that you’re tracking their errors in behavior and seeing how they’re sleeping, usually you’ll find – There was a great study by Chuck Seizler that showed that people, doctors, who were on a 30-hour work schedule versus a 10-hour work schedule were making 700% more errors…


DR. MEDNICK: …during their workday.


DR. MEDNICK: Even though this is not something that they would ever probably admit to.

CAVANAUGH: Right. Let’s take a call. Al is calling us from El Centro. Good morning, Al, and welcome to These Days.

AL (Caller, El Centro): Good morning to you. This is a very subject – a subject very close to me. I’m a retired commercial airline pilot and quite used to flying on the back side of the clock and lost my commercial pilot’s license actually in ’02 at age 57 from supraventricular tachycardias and medication never solved the problem but just last December I was finally diagnosed with sleep apnea and I’d like to take your – hear your take on the chronic effects of flying on the back side of a clock and under a lot of exhaustion.

CAVANAUGH: Al, thank you very much for that. Dr. Kay, Dr. Mednick, I’m wondering, but Dr. Kay, you told us in very graphic detail how that kind of disruption of one’s biological cycle can have very, very bad effects over the long haul.

DR. KAY: It can do, and of course, you know, this is something that we all need to understand is, you know, you can do these studies on the level of large groups of people and populations and you can see these propensities for chronic diseases in shift workers. When it comes down to each individual like the caller, the etiology of a disease can be quite complex and so there may be a component in Al’s issue in terms of his life as a pilot and constantly being jet-lagged, as it were, contributing to the things that he shared with us. But it’s also quite likely, as well, that there are other contributors to a disease state, and so for the case of each individual working with their physicians, they’ve got to figure out how much might’ve been…


DR. KAY: …contributed from the disruption of their circadian life from other factors.

CAVANAUGH: I want to ask you both, Dr. Kay and Dr. Golden, about the Center for Chronobiology. What is it that you’re hoping to achieve? It seems like this kind of shift work and jet lag are so much a part of our life that that’s really not going to change to any great extent, so are you ultimately thinking about coming up with a pill or coming up with something that someone could take or do in order to countervail the effects of really going against your biological clock?

DR. KAY: The answer is absolutely. And you’ll see at our meeting on Friday that several representatives from major drug companies will be present. There’s a real interest in chronotherapeutics, which is the idea of developing chemical approaches to altering our clock. And I’m personally involved in creating a start-up company that’s called Reset Therapeutics that actually has the goal of identifying clock modulating drugs. And, of course, this is way into – quite a few years into the future but there will be a possibility that we’ll be able to modify the circadian clock and so contribute to reducing these disorders like metabolic syndrome that are associated with jet lag and shift work.

CAVANAUGH: And Dr. Golden.

DR. GOLDEN: I’d like to point out kind of the other side of this, which is, you know, on one hand we’re doing research to learn more about the clock to help people deal with their clocks but on the other side what we’re finding is that the clock is controlling almost everything that is going on in all of these different kinds of organisms. And so learning about the clock helps us study these other processes so if we want to study photosynthesis in plants, if we want to understand any kind of metabolism in an animal or a fungus, we need to understand what its clock is doing because that clock is meddling with everything that we’re trying to study and if we don’t understand that clock control is occurring, we’ll misinterpret our research.

CAVANAUGH: Things like metabolism and obesity, issues like that, you think also might have to do with a certain biological clock and perhaps help people learn how to deal with that.

DR. GOLDEN: Right. So all of these various processes that people who aren’t chronobiologists will study, they may not realize that there are increases and decreases in the activity of the processes they’re looking at because they don’t understand about this underlying circadian control. And so that’s the other importance that comes out of this work and that’s why collaboration is important.

CAVANAUGH: I don’t want to leave this topic, Dr. Mednick, without talking about what’s coming up this weekend and, of course, it’s daylight saving time. And, you know, it’s funny and I know you’ve been asked this question a million times, how one hour can make a difference in the way people feel and the way people function. Tell us a little bit of why it is, it’s so very minor a change can disrupt people to an extent that they really feel it.

DR. MEDNICK: Yeah, it’s amazing. If you look at the statistics right after we change our clock just for one hour, you see an increase in car accidents, an increase in heart attacks, a lot of arrange – people are more fatigued obviously and that leads to an increase in fatigue-related accidents. And I think this is really showing you the exquisite control of our circadian rhythms on our behaviors and that even if you lose that one hour of sleep in the morning, that your whole day could actually be affected by this and that it does – it doesn’t just take one or two days to get over it, like some of these effects of increased heart attacks can actually exist the week after you change your clock, so this is a long term effect, that it takes a while to even get over just one hour of shifting. So obviously for my interest in this, is, you know, what can we do with sleep to allow us to adapt to these changes, not necessarily – I mean, I’m very interested in looking at pharmacology as well but is it possible to do things naturally as well, and either, you know, add a nap to the day that you have lost an hour so that your drive home isn’t as dangerous as it could be, add naps throughout the entire week, or it is actually, you know, can you start work a little bit later and so that we actually adjust a little bit more slowly to this daylight savings or even the radical approach to ending daylight savings is another possibility. But it really shows how we really do need to look very closely at the dangers of shifting our schedules without really being conscious of adapting our daily lives to that daily shift.

CAVANAUGH: So it might be a good idea to maybe take a nap or two this week or…

DR. MEDNICK: Oh, I think so, yeah.

CAVANAUGH: Yes, or even the day of.

DR. MEDNICK: The day of mostly because that’s the day that you’re really going to be losing the sleep. And, you know, even on a larger scale and a more extreme scale, when you look at shift workers on the drive home, it’s not necessarily that they’re making mistakes at work but they get into more car accidents when they drive home and so you see this on Daylight Savings Time a lot more increased car accidents. Why is that? Probably because people are either – their brains aren’t functioning at the level they need to be or they may even be falling asleep at the wheel.

CAVANAUGH: I want to thank you, Dr. Sara Mednick, assistant professor in the Department of Psychiatry at UC San Diego, author of…


DR. MEDNICK: …Change Your Life."

CAVANAUGH: Thank you so much for speaking with us. And Dr. Steve Kay and Dr. Susan Golden, I want to thank you both. And I want to let everyone know that the nation’s experts on chronobiology will gather for a symposium called “From Cells to the Clinic.” That’s at the UC San Diego campus this Wednesday, Thursday and Friday. And thank you both so much for speaking with us.

DR. KAY: Thank you very much.

DR. GOLDEN: And thank you.

CAVANAUGH: And if you’d like to comment about what you heard, go online, Coming up, the desert flowers are in bloom. We’ll get tips on visiting the Anza-Borrego wildflowers. That’s as These Days continues here on KPBS.

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