Interview: Why daylight is the secret to great sleep | Christine Blume

0:02This is TED Health, a podcast from TED, and I'm your host, Dr. Shoshana Ungerleider. After residency, I spent a lot of time working night shifts in the hospital. It was a strange period of my life, living under fluorescent lights, sleeping in short, scattered bursts, and then wondering why I always felt just a little bit off. Back then, I thought exhaustion was just part of the job. But what I didn't fully appreciate was how much our bodies rely on light, real, natural daylight, to regulate everything from mood to metabolism to the ability to fall and then stay asleep. In this episode, sleep scientist Christine Bloom explains how daylight keeps our internal clocks ticking in sync and why so many of us are out of rhythm without even realizing it.

0:50So if you've struggled with sleep, burnout, or just feel disconnected from your own energy, this talk might be your wake-up call. Because better sleep doesn't always start in the bedroom. it might start by stepping outside. And then stick around after the talk for an interview with Dr. Meredith Broderick, a neurologist and sleep expert who helps patients address the root causes of their sleep issues through science-backed approaches. We'll explore why so many of us struggle with sleep, me included, and what we can do to finally get the rest that we need. But before we dive in, a quick break to hear from our sponsors.

1:34And now, Christine Bloom. On a usual Saturday, you wouldn't find me here. And I mean, of course, I don't give TEDx talks every Saturday. But what I mean is, you probably wouldn't find me in a museum. Rather, if you were looking for me, you'd probably have to go to the mountains. And that is because I absolutely love hiking. And in addition to just being outside and being in the nature, what I really like is this feeling of physical exhaustion, sort of this satisfaction you can feel in every single muscle. And in the evening, when it's time to go to bed, I absolutely cherish this amazing sleepiness that fills you from head to toe.

2:19Now you might say, well, of course she's tired. She's been hiking all day. Plus, not to forget about the effects of supposedly fresh air. But there is one factor that most likely outweighs the effects of fresh air, and perhaps even physical activity. And that is exposure to natural daylight. And today I hope to convince you that we should all appreciate daylight as sort of a natural soporific. and hopefully by the end of the talk you will also recognize that we should all pay more attention to our daily light diet. But let's start with a question why daylight is so important for our organism, for health and eventually for sleep.

3:11Now throughout your body in each and every single cell, there is a tiny molecular clock ticking inside it. And to keep these millions of clocks in sync, we have one central body clock that is located in the brain in an area which we call the hypothalamus. And like the conductor of an orchestra, it communicates the time of day to each of these molecular clocks. And this way, it is able to regulate bodily processes in sync with a time of day. For example, it causes your body temperature to increase in the morning and to decrease in the evening. It choreographs the release of certain hormones at appropriate times and in the evening when it's time to go to bed, it will also make you tired and sleepy.

4:06But given this precise synchronization between internal or biological time and external time or environmental time, it seems clear that the body clock cannot be blind or isolated or shut off from the environment, but rather it needs to receive information about the time of day from the environment for it to synchronize with sun time. And this is achieved by close connections between the internal biological clock in the brain and our eyes. And now you may know that in the human retina, there are different types of receptors, photoreceptors. So receptors that send light. And classically, we distinguish two types, the rods and the cones.

5:00But this is not the whole story. because only fairly recently, only in the early 2000s, another type of cell has been discovered, and we call them retinal ganglion cells. These cells do not contribute to a visual impression, but they're exclusively designed to sense short wavelength proportions in daylight. Sometimes we also call this blue light. So they're designed to extract important information about the time of day from the environment and pass this on to the internal biological clock in the brain. And I guess you've all experienced how well this biological timing system, this connection between our biological clock and the external world or our eyes works when we, for example, travel across time zones.

5:56Now, how much light do we actually need? How much light is enough for the positive effects on, for instance, sleep to occur? And I have to admit, this is not so easy to answer. But I think what we have to keep in mind is that the biological timing system has evolved under the open sky and not in offices or museums. so it is also optimally tuned to the conditions we find outside. Office light or light in rooms is in no way comparable to what we find outside. And therefore, from a scientific perspective, I can only recommend you to spend as much time as you can under the open sky, but try to make it at least 30 minutes per day.

6:46Now, let's finally talk about sleep. And I've repeatedly alluded to the fact that daylight is beneficial and important for sleep. And in this context, I'd like to share a little story. So last year, I had to go to hospital for surgery. And generally, the hospital environment is a very challenging one for sleep. Because you spend way too much time in bed not moving much. You might be in pain. Now and then someone comes in to check on you, even during the night. And if you're as lucky as I was, you have a snoring roommate. And because you, of course, don't get a lot of daylight. And that's why many people, while they're in hospital, ask for sleep medication.

7:39But as I consider myself to be a generally good sleeper, and also because I know how these drugs work, I didn't want this. But I knew there was something I could do to help my body sleep as well as possible, even in this situation. And that was to maximise exposure to daylight. Because as a sleep scientist, of course I know about the research findings. I know that the more daylight that you get, the more tired you will be in the evening, the easier it will be for you to fall asleep, and the better the experience sleep quality. And in addition, daylight exposure has also been shown to increase proportions of deep sleep, which again has been linked to processes of tissue repair.

8:31Something not to be underestimated after surgery. And beyond the effects on sleep, we know that patients in brighter rooms experience less pain and less stress. and also the effects of daylight on mood are well established. So I thought it might be time for me to put into practice what I often preach and I have to confess that usually I'm much better at giving advice than following it myself. But here's what I did. So first when it became free I asked the nurses to move my bed to the window place because that does not only give you power the fresh air supply, which is highly recommended in the hospital.

9:14But it also maximizes daylight exposure, even though you're inside. Second, as soon as I could leave my bed again, I went to the park for short walks. And last, every meal I had, I tried to take on the little balcony. Did it work? Well, that's a bit difficult to say, because it of course was a single case study. but from patients suffering from insomnia, so one of the most common sleep disorders, we know that light therapy is beneficial. And therefore, I would like to encourage all of you, and perhaps especially those who might belong to the 25 % suffering from sleep problems, to start your own single case study.

10:02Thank you.

10:13That was Christine Bloom at TEDxBasel in 2022. Now I want to welcome Dr. Meredith Broderick to help us look deeper into this topic. Dr. Broderick is a neurologist and sleep medicine specialist who helps patients address sleep disorders through personalized, evidence-based care. She's also a dedicated educator on a mission to help the millions of Americans who struggle with chronic sleep issues. Today, we'll explore why modern life so often gets in the way of good sleep, what actually makes a difference, and how we can all get better rest. So many of us, I think, treat sleep like a luxury, something that we feel like we can maybe catch up on later.

10:55Why do you think sleep has become something that we deprioritize or even feel guilty about needing? I mean, I think there's this narrative in the sleep community that sleep is a superpower, when really, I think our superpower is our ability to stay awake and put off our need for sleep. You know, if you really think about this as a survival tactic, if we're in danger, or if we need to hunt for food, we can put off this need for sleep. And I think it sort of pervades all culture that I'll sleep when I'm dead because I have one life to live. And really, it's a balance of that. It's being able to live your life and choose things where maybe you put off your need for sleep a little bit because that's part of living a fulfilling life.

11:37But also, you know, trying to help people understand, like, there's only so much you can do that before, like, the body breaks down. I think that people can sort of feel like they're getting away with it for a while. But there's going to be something that happens long term, whether it's just not being able to manage that sleep loss anymore and having some kind of health issue show up. What would you say to people who find sleep inconvenient or don't understand its value? Like, how can we value this process more? I think education and letting people know that you could be underperforming or not functioning as well as you think you are.

12:15And then also understanding the toll that it takes on your health long term. Yeah, for sure. You know, for me, it took a good eight years after my residency to get my sleep back on track. I was doing night shifts at the hospital, which I really liked. But I found that my sleep just got so disrupted. And then my energy, my diet was all affected. I mean, it's just wild how much sleep really is integral to everything about our lives and staying healthy. And in medicine, obviously, we sort of accept the suffering as part of just what we have to go through and kind of become desensitized to it. But I think it happens to other people, too, in other professions.

13:00One of the issues that comes up a lot is having more technology, making us less connected to our natural world and our natural environment. It gives us more freedom, which is great in a way, but it has decoupled us from this intrinsic relationship we have with the sun and the solar cycle. Being on devices and having lighting all night long and having access to so many things any time of day. You know, text message and emails and the news and work, work, work. So I think that's the other thing. I mean, it's designed to grab our attention. No, I know. I would say like when I can take a vacation and not be so hooked to my computer, my cell phone, you really do see how you get more attuned to what the light outside is doing.

13:50And for me, it's so helpful in terms of getting my sleep on track. Yes, and it's interesting how desensitized and unaware we become to living that way. I always use the frog in the pot to describe to people how that happens, is that it happens to you so slowly that you sort of lose your touch of how much better you could feel. Oh, definitely. I see sleep as sort of this really under-recognized kind of social determinant of health and a big driver in so many issues of chronic illness that we're seeing plague our society, right? Yeah, and it makes sense too, because it's a systemic function in the sense that it affects every organ system, not only our cardiovascular health, but our brain health, our mental health.

14:39It causes inflammation. You know, it has all these ripple effects to our complete health, you know. So one of the biggest issues I hear is people struggling to turn off their brains at night. We touched on this a little bit already. Is there anything surprising or maybe counterintuitive that you've learned helps people to calm their minds at night? So when people's brains are racing at night, from a neuroscience perspective, what we think is going on is the brain is actually trying to perform a function. So you can think of it needing to file things and organize things to perform this function of sleep.

15:16and if you're so busy that you're going from thing to thing to thing with no downtime during the day your brain is going to do that at bedtime and it's going to manifest in how you experience that as sort of these erasing thoughts so if you give yourself time to be alone with your thoughts the best way to describe it is daydreaming and to give yourself space for that during the day your brain won't need to perform that function before you sleep. And we think that our consciousness, we weigh that so heavily, but our brain does so many things we're not consciously aware of. And you're just providing space for that function to occur.

15:55Ooh, I love this, like prescribing daydreaming. Yes. Do you actually do that with patients? Yeah. And it's been studied a lot in psychology. It's called scheduled worry time. And it's been studied and shown to reduce stress and anxiety and and chronic worry but I think the thing is is it's hard for people that feel very stressed to take time because there's this inclination like I need to do I need to accomplish I need to achieve in order to lower my stress I need to cross all these things off my list but you know creative people I think intuitively understand this more because in order for them to come up with ideas they come spontaneously out of nowhere and you sort of have to have all these distractions away in order to do that.

16:39So I always tell people like, have you ever like woken up and your brain solved a problem? Or have you ever been standing in the shower and you suddenly remembered something you forgot? Your brain is still working on problems, even when you're not consciously thinking about them. And you sort of just have to trust that process. Oh, my gosh, I totally resonate with that being in the shower and then coming up with this crazy idea that I've been thinking about for like months, and it comes to me in the weirdest times. So when people can't quiet their minds, it's common for folks to reach for sleeping pills as a first step or supplements like melatonin.

17:13Why do you think that is and what's the risk of relying on medication instead of treating the underlying issue? This is like such an iceberg, but I think it's easier to take a pill. They're available and sometimes they do work for the short term pretty well or intermittently. I think that there are times where it's completely appropriate and there's times where it isn't more of the psychological nature to it. I was thinking about this for a case that I was seeing this week. And if you're familiar with Pema Chodron's book, there's this one called When Things Fall Apart. And if you're ever having a bad day, I highly recommend reading it.

17:50She talks about these maras and they're things that try to attack us and challenge us. They're things that sort of throw us off. and she talks about this Buddhist parable where the Buddha is waiting for enlightenment under the tree and there are these arrows shot at the Buddha and they turn into flowers. The kind of meaning behind that is that the things that try to hurt us or feel like they're going to hurt us, they can actually help us and can be clues and turn into something really beautiful. And so for a lot of people, that sort of anxiety or racing thought or unpleasant sensation that they're experiencing, it's a clue that there's something unresolved.

18:30And basically, instead of reaching for a pill or reaching to sort of make that feeling go away, it's looking inward and trying to figure out where's that coming from. And also knowing not everything is supposed to feel good. And these emotions are, they're part of life. And sometimes they're meant to help guide us. No, I love what you're saying about letting what comes up for you really be a place to maybe lean into. I think that's really hard to do, especially in the modern world where it's, you know, I need a quick fix for this. Let me just get on, you know, telehealth with a doctor or quickly move on.

19:10But I do think it's really powerful when you can sit and kind of ask the questions of this thing is keeping me up at night. What is this about? And sort of to that end, I want to talk about cognitive behavioral therapy for insomnia or CBTI. I know you practice it. Yes. Cognitive behavioral therapy for insomnia or CBTI for short is a behavioral treatment that has multiple modalities to it. So it includes these five components. The first one is called sleep restriction. The second one is something called stimulus control therapy. We also have cognitive therapy. So this addresses sort of dysfunctional beliefs and ways of thinking about sleep.

19:50Sleep hygiene is a fourth component. And then we also have relaxation or stress reduction. And it's usually a four to six session protocol where you would see a practitioner every week or every other week. And you keep sleep diaries throughout this program. And usually these five components, they're implemented in a very strategic fashion. So basically it addresses these components of chronic insomnia where people have developed these coping mechanisms oftentimes that keep fueling the insomnia. This actually wasn't something I even learned about in medical school, but it's recommended as a first line treatment for sleep issues.

20:32And I can actually confidently say from personal experience, it can be incredibly effective. But I think so few people know about it. Why do you think that is? And what makes CBTI so different from everything else that people typically try? I think that we have an access problem with CBTI. I don't think we have enough practitioners. Sometimes it can be expensive. I think that's number one. The other thing is, is that it's very time consuming and requires a lot of time commitment, but it's a behavioral treatment. So there's kind of a readiness and a willingness. And the treatment itself asks people to change their behavior and change the way they think about sleep.

21:17And I think that there's a right time for people in the same way that there's a right time for someone to be like, okay, I'm ready to start managing my weight into a healthier place or eat better or get more fit. It's similar to that where I think people need to have the right sort of space in their minds or the bandwidth to do that. That makes sense. It's more like actual talk therapy than anything else. There's no medication involved. When I did it, I was shocked at how helpful it was. I kind of was thinking, okay, I'm going to tell you about how I feel about sleep. Like that's going to help me.

21:56Are you going to ask me to journal? Like, really? That's going to help my 20 year history of insomnia? And it actually worked. So I was quite pleasantly surprised by that. so beyond CBTI there's a lot of hype around sleep blue light glasses supplements gadgets from your perspective what's more noise than help and what actually moves the needle for people I love all those things in the sense that what I tell people is you know if you took a professional golfer let's say they're going to have all the best tools they're going to have the best golf clubs and they're going to have all these accessories that are great so they enhance everything, they can make sleep more enjoyable, they can make it feel comfortable.

22:43But at the end of the day, sleep health really is health. And so if you really want to look holistically, I think the research that's emerging, even if we look at things like glymphatic function and deep sleep, they're really a byproduct of vascular health. And so I always tell my patients like, if you don't have your blood pressure controlled, that's a higher priority to me than like what your sleep tracker is showing. So I want people to think about their total health. So not just zooming in on their sleep, but I want them to think about all these foundational things like their nutrition and physical activity and their mental health and their community, in addition to all the things we look at in medicine, labs and blood pressure and preventative screenings.

23:29You're a neurologist, you're trained in sleep medicine. Tell me, how can people distinguish between bad sleep habits or conditions versus a more serious medical issue? We have a lot of really good screening tools. So for obstructive sleep apnea, for instance, there's something called the stop bang questionnaire. For insomnia, there's the insomnia severity index. And this can truly give you just by taking a quiz online, an idea of the severity. I think those are good. A lot of those have been heavily researched and validated. Obviously, if you have access to talking to a sleep expert about it, I think that's great too.

24:11But I think those questionnaires are really accessible to anybody and free and a good place to start. And important to like take seriously if you're having sleep issues or your bed partner says you're stopping breathing at night, even at a young age, it's important to take it seriously, right? Absolutely. You know, trying to have longevity that everyone's talking about, it's like a moonshot, right? And so you want to aim for it from the very, from wherever you start, you don't have to keep redirecting. And so that's what you're doing. The sooner you start taking care of your health, the more on course you are.

24:46Yeah, so we're talking about adults, but I'm also wondering about what sleep disruption looks like in children. So what are some of the signs that a child's sleep struggles might be something more serious, like even sleep apnea? And why is early intervention so important? Yes, I see quite a few kids in my practice. And I always tell people there are three components that you want to think about in children. So awareness is one, really having parents recognize when their children have sleep problems. So, you know, having a child that's sleepy, they fall asleep every time I'm in the car, having a child that has ADHD like symptoms, they can't stay in their seat, they have impulse control issues, they're irritable, behavioral problems.

25:33Those are all things that are red flags for sleep disorder. And I think that there is probably some misdiagnosis of kids with sleep disorders that get an ADHD or an ADD diagnosis. So awareness is one. And interestingly, because there's this weird badge of honor to have a child that's a good sleeper, there are a lot of times where children who are excessively sleepy are not really caught. Because when you're a parent, the only time you really have to yourself is when your kids are asleep. And sometimes it's not such a bad thing. But I will see parents that are very attuned. And they'll just say this kid is different.

26:13And I know something's wrong, because they're too sleepy, they sleep too much, they're hard to get up. They just need way more sleep than my other kid. The second of the three, so I call it like an ABC. So awareness and then breathing. So breathing is extremely important. And in kids, one of the things we're going to look at is there's a lot of, I would say, like overlap with dental health. so mouth breathing allergies those are all going to impact the growth of the craniofacial complex and that's really a huge risk factor for obstructive sleep apnea later down the road and in childhood it's this very special opportunity to help facilitate that growth and to have the tongue in the right place to help guide the growth and to develop speech and swallowing patterns.

27:01So speech issues is another thing that comes up as something that is a clue of maybe that we have these airway issues. We have a tongue tie, we have, you know, allergies with adenotonsillar hypertrophy with mouth breathing and things that are going to affect the sleep as well. And then the third I would say is conditioning. So when I say conditioning, that's really what we think about when we think of sleep hygiene. So this is where parents are training their children to have healthy sleep behaviors. So having a regular bed routine, having a regular bedtime, having a wait time that's regular, and all those healthy sleep habits.

27:38And there's a large spectrum of what's normal or healthy. But those are kind of the three major components with for children, I think, to think about. So helpful. I would have never thought of this as something around respiratory health that starts in childhood, but it makes perfect sense that parents being attuned to their kids' breathing and sleeping is so important for a long, healthy life, right? It's interesting how people can have such disruptive breathing during sleep, but if any of that was happening to someone and they were aware of it or they were awake, we would like take them to the hospital, right?

28:15Mm-hmm. No, it's so true. For those who might be dealing with more complex issues, people who say they've tried everything and they still can't sleep, what would you say? Like, where do you begin when someone feels hopeless? I mean, obviously, I want someone to have seen a sleep medicine doctor. And one of the things about our field is it's multidisciplinary. And I think that different disciplines have different angles or ways of thinking about it. So sometimes it can be helpful. For instance, if you saw a pulmonologist and maybe you have an insomnia problem maybe you want to see someone with more of a psychiatry background or a neurology background or maybe you even want to see a behavioral sleep medicine specialist and so I think getting a second opinion is something that I would always recommend if someone doesn't feel like they're getting what they need because I think sometimes as you've probably noticed as an internist sometimes you're kind of like a Sherlock Holmes and you just need more time and information to really figure it out Yeah, I say that all the time.

29:16If things aren't making sense or they're not getting better, or even if you just want more information, always asking for, if you're able, another opinion on it. So Meredith, to wrap up on a practical note, what are a few small but powerful changes that anyone can make today to reset their sleep cycles and start feeling better? So number one, sleep hygiene is very important. I think of it like dental hygiene. It's something you need to do to prevent from developing a sleep disorder. That includes things like having a regular bedtime, regular wake time, spending an healthy amount of time in bed, right?

29:50So if you're having trouble feeling restored, don't spend more time in bed. That's not likely to help improve your quality of sleep. Also with sleep hygiene is minimizing things like caffeine and alcohol. And if you feel like you've exhausted your sleep, you can improve your sleep indirectly through these other things like having better nutrition, having more physical activity, getting outside, those things also improve your sleep. Sometimes people get over kind of zoned in on sleep, maybe sort of redirecting to something else can be helpful. Fantastic. Thank you so much. I've learned so much from you personally and professionally, and I'm grateful for your time today.

30:30Oh, thank you for having me.

30:36And that's it for today's episode. Thank you so much for listening. TED Health is a podcast from TED. And I'd love to hear your thoughts about this episode. Send me a message on Instagram at ShoshanaMD. This episode was produced by me, Shoshana Ungerleiter, and Jess Shane. Edited by Alejandra Salazar and fact-checked by Vanessa Garcia-Woodworth. Special thanks to Maria Lages, Farrah Degrunge, Daniela Balarezo, Constanza Gallardo, Tansika Sangmarniwang, and Roxanne Heilash.