We are the Association for Child and Adolescent Mental Health, or ACAMH for short. And this is ACAMH Learn. Welcome to Mind the Kids. I'm Dr. Jane Gilmour, Honorary Consultant, Clinical Psychologist, and Child Development Programme Director at UCL. And I'm Umar Toseeb, Professor of Psychology at the University of York, focusing on children and young people's mental health and special educational needs. In each episode, we select a topic from the research literature. And in conversation with invited authors, sift through the data, dilemmas, and debates to leave you with our takeaways for academics and practitioners. Today, we'll be discussing sleep and its relationship with adolescent mental health. This episode is called regular sleep, the balm of hurt minds. OK, let's talk about sleep. So I'm going to start with a small-- I don't know if it's a brag, but it's like, "ooh, look at me, I so lucky" kind of vibe. I regularly get only nine hours sleep at least, if not more, seven days a week. Like I am not messing about when it comes to sleep. I go to bed at a certain time. I wake up at a certain time. I will leave social events early so I can get to bed on time. And it's amazing. And a lot of my friends are like, you sleep so much. And I'm like, yeah, it's good. Even on holiday, even on holiday, I will go to bed at a certain time and I'll wake up at the same time that I wake up at home. This is interesting because my smartwatch gives me round of applause when I have regular sleep, and I never really thought about that metric before reading this paper interestingly. So the regularity of sleep was something I thought it was the length, but now I'm looking at my smartwatch with new eyes and thinking about it. I'm actually a very early riser and there is some very poor data. I want to emphasise the poverty of the scientific data here, suggesting that late risers have a better cognitive attainment. It's obviously very poor. I mean, it's actually correlational data. And it's not very good. But the idea that somehow a late or an early riser might have a different outcome in life is quite a tempting heuristic. The science is a different question altogether, I think. And we're going to talk a bit more about that. Yeah, I think we will. And I think I've recently become-- well, I'll just say I've recently become more interested in sleep research, but I think by accident, because I've moved to a department in my job where there are lots of people who do sleep research. So just by design now, I'm now involved. I'm now more interested in sleep research because people are talking about it in staff meetings and when you have conversations with people. So I have more of an interest now than I did previously. But it makes sense to be interested in sleep because, well, if my numbers are correct, we spend about a third of our lives sleeping as if sleeping eight hours a day. And there's 24 hours in a day. It's a third of your life. And if I'm sleeping 9 or 10 hours, then it's more. So we spend so much time sleeping that we should be investigating it. I mean, it is an area that is certainly expanding in the scientific literature. I mean, I'm really interested in the idea of larks and owls, looking at eveningness and morningness, which is the phraseology for your preference for late or early waking. And there's some interesting evolutionary hypotheses about why that might be, because of course, it makes sense to have somebody who's awake at some point in the 24-hour cycle. So having a variety of sleep preferences in the sleep cycle would be preserved. It makes sense. I think it's quite interesting. I was also very interested in the methodology here. So we're talking about some of the capacity to think about moment to moment experiences and how they relate to sleep. And I think you were interested in that area as well. So the EMA topic is one that we might get on to in the course of our discussion. Yeah, and one of the things that I wanted to raise on that point I was on LinkedIn, I think it was. And must follow this person, but I don't know who it was. But they posted something about-- I think they were a developmental psychologist. And they said that all these theories of why people experience mental health difficulties. And a lot of them focus on structural things and processes and those kinds of things. And I think he said that once he'd had children, he realised that sometimes their children were upset or anxious or whatever just because they hadn't slept well or because they haven't eaten or because they were too hot or those kinds of things. And they said that then their interactions with adults at work were viewed through that same lens of, oh, this person is not being difficult because they have a difficult personality or whatever. It is just maybe they haven't slept or maybe they haven't eaten well. And I think it was focusing on those everyday experiences that might lead to a specific interaction rather than attachment styles or trauma or adverse childhood experiences or societal factors. So thinking more about how your immediate context or immediate experience might impact on your behaviour. And in fact, I think I said, EMA. I don't know if I unpacked what EMA stands for, Ecological Momentary Analysis. I'm involved in a study headed up by Emily Midouhas at UCL, and we're using EMA, funnily enough, looking at the bidirectionality of parent-child relationships. And it's such a fascinating tool. I've never used it before becoming involved in that study. So it can look at data points at regular points in the day or at random points. But the key is it's embedded in day-to-day activities. So it really makes sense to use that as a tool when we're thinking about sleep and bidirectionality of mood and sleep and how they relate. So this is, for two reasons, both the content and the methodology. This is such an interesting paper. Yeah. And before we bring the guest in, I just want to revisit something. Well, put another reason forward for why sleep is important to discuss is because-- we had that podcast previously with Ian Goodyer. It was called "Rebooting the Great Psychotherapy Debate," where we talked about the findings of-- I think it was a [INAUDIBLE] trial. And they looked at which symptoms of depression were being targeted or were improving as a result of therapy. One of the findings was it seemed to be that therapy might be working by improving symptoms of insomnia, which suggests that sleep might be an important target for intervention for those who are experiencing mental health difficulties that are in need of professional support. So I suppose it's not the first time we're talking about sleep, but it's the first time we're talking about sleep specifically with relation to mental health in adolescence. I'm aware that we're perhaps we should crack on and invite our guests in, because there's a lot to talk about. And I want to talk about the relationship between sleep and the teenage brain, particularly, and looking at the ways in which that might impact on academia and attainment. But I think that might be something that we could think about in our wrap-up when we talk about the implications for academia and clinicians, because we have an expert on our doorstep who could help us unpack some of these questions. Let's open the door and let them in. So today, we're joined by Dr. Konstantin Drexl from Lausanne University Hospital and the University of Lausanne. Konstantin is the lead author of the paper, "Toward an Idiographic Understanding of the Role of Sleep-Mood Dynamics in Adolescents' Internalising Symptoms," published in JCPP Advances. Welcome, Konstantin. Thank you very much. Thank you for having me. Oh, well, it's our pleasure. So let's just start with a brief primer on sleep. So I know that every part of the literature, whether it's psychology, developmental psychology, or any other field, you have your specific terminology that makes lots of sense to you, but it doesn't always make sense to people outside of that specific field. Now, I know that Jen and I have just had a conversation about sleep, but I know that we've just used general terms that people might understand. I just want you to give us an overview of what the terminology is within the sleep literature that you will be referring to in this discussion. So let's use three very basic key terms, like what is sleep, chronotype, and circadian rhythm. So if you want to define sleep, that's a very broad term. But it's basically the natural state of rest for the body in terms of physical activity, for the mind in terms of rest from consciousness. But at the same time, the brain doesn't stop being active during the night. So it's just that we are not aware of what is happening. So the brain goes through different cycles and is even very active together with the body for healing and also for processes like memory consolidation. So when you talk about therapy and what's the implication of sleep, it's also part of the overnight therapy that happens. And we haven't yet understood how that works. Sorry to interrupt. I'm just going to say because Matt Walker uses the phrase that sleep is the glue of the memory. And that really, I think, when you are new to this literature and unpacking this terminology, it's so interesting to think about what its function is and so much is unknown. So it's really interesting. Please carry on, sorry. Yes. And, what is timing this glue from our real world experiences to our inner world, emotional experiences is often chronotype is the preference as to when during the day and night we prefer to place our sleep. And this is known to have some genetic sources that are supposed to be moderately or strongly printed in our genes. At the same time, it's a question of how we interact with the environment in terms of light exposure, social activities, and also the experience of stress. How we organise our sleep and rest cycle during the day, that's touching our circadian rhythm. So even if we have a chronotype of a certain tendency being early or even in person, the circadian rhythm can deviate from that towards a certain point. And I've heard terms like REM sleep, non-REM sleep. Yes. So REM sleep is one of these phases that our brain goes through during the night several times. So after going through light stage of sleep and then more deep stages of sleep, the REM, which stands for Rapid Eye Movement sleep-- was initially called the paradoxal stage of sleep because even if most of the body movements are turned down, the eyes, they move horizontally very quickly, and the brain is active as if we were awake. So when you look at those EEG sensor data recordings, there are little differences actually from being awake. So that's the phases where reprocessing happens and where memory consolidation happens. And we were talking before we invited you in about sleep duration and routine of sleep. But when we're talking about sleep quality, is REM sleep the good stuff that we need? I would say parts of it happen during REM sleep. And it's, of course, very important. Good sleep has different dimensions. Duration is one of them. Duration makes REM sleep happen at the same time if, for example, people are very sleep deprived, they find difficulties to enter REM sleep in the first few phases. So there are kind of homeostatic processes that are in the perfect middle where you are tired enough to enter these cycles and at the same time not too tired, let's pose it like this, to enter this phase early enough during the sleep so that you can repeat the cycle several times. Why would that be-- so it sounds to me as if, that if you are, let's say in crisis and very, very tired, you wouldn't get the opportunity to go into REM sleep. Well, does it take up more cognitive resource? Or why would you not get the opportunity to get into REM sleep? So imagine if you had-- you referred t crisis, and the follow-up project of this study is actually happening in hospitalisation unit for suicidal crisis. So that's where we are heading right now. So yes, sleep is like roller coasters during suicidal crisis. And there are hours where adolescents don't find sleep, and then pressure builds up and builds up. And when finally the body can't avoid actually sleeping, no matter which level of alertness is going on, then they enter the most maybe efficient way of restoring the basic functions like non-speculating basically. But it's known that in this high pressure situation, people fall into a deep sleep with basically no movements. And if it's very short, then sometimes it happens that patients don't even enter REM sleep during the night. That's extreme. Like we are in the middle, there are kind of tendencies. We've picked up on two things that we were going to ask you about. So I want to ask you about the importance of sleep during adolescence. But then Jane, I think, wants to know more about sleep pressure and this build up pressure, which you've touched upon. So let's talk about why is sleep important during adolescence? And why should we be interested as researchers? And then also why should parents, teachers, et cetera be concerned with adolescent sleep? So there are several reasons. So one is the brain development. So during adolescence, the brain is kind of sorting out which are the connections that are really relevant for learning? So there's this great task of pruning and the brain maturation. And a lot of that is happening during sleep. And at the same time, we're talking about the phase where many first psychiatric symptoms start to appear during adolescence. And sleep also is under high pressure from different sides during adolescence. So while, just as a matter of a natural trend, adolescents start to prefer later that times, they still need the same amount of sleep between 8 and 10 hours. At the same time, the school times maintained at early hours just if they were kids. So this collides in a conflict between the biological rhythm and the suicidal demands. So this is a common situation of pressure on sleep health in adolescence. So many adolescents are concerned. And that's interesting because particularly we know and partly because of the state of the brain during the teenage years that the habits you form during adolescence may become lifelong habits because of that kind of porous quality of the teenage brain. So it's interesting that, obviously, there's a biological shift of that pressure to sleep. But I wondered about not just about timing, but about sleep habits, if you like. Are there data showing that sleep habits, not just timing, but sleep habits that you develop during adolescence might maintain during the lifespan and how that might impact longer term? That's a great question. And I think it's difficult to answer. If you think of yourself when you had-- when you were 14 years old, did you imagine that screens were around at this-- yeah, at this point and that you were like so available at any hour of the day for messages coming from different parts of the world or news or whatever? So when we talk about sleep habits, maintaining throughout the life, I mean, the conditions change, even in history and even in different stages of our lives when we become parents and we take care of our children who have sleep cycles that are much shorter, and then we get up in the night for them. So that's just one example. So it's difficult to define what would be the sleep habit that is really maintained throughout life. At the same time, for sure, there are phases of several years, maybe destinies in the life of a person where sleep habits can be very stable. And the experience is this my life is happening with me organising my sleep in this way, drinking coffee up to a certain time in the day, having a sleep routine or not interfering with my sleep, and being more or less OK with my o'clock in the morning. It's interesting. And I think this discussion is not about technology, but of course, it does have an impact on sleep. And I think, I mean, this is maybe controversial, but I'd be interested to see what your comment is. I think for parents, the habit of not allowing phones in youngsters room or anyone else's room at night is probably one of the single most effective things they could do to invite good quality sleep. Because particularly, if you're a teenager, that phone stands for everything that matters to you in your life. And you're expecting a young person to switch off and not wonder what's going on in their social world and blah, blah, blah. So yeah, it's a really good-- I hadn't thought about the long-term data in terms of screens. So it's a really good point. Can I just add a question there, follow-up question to what James just said is, what's the stuff about blue light, like white light or blue light? What is it? Something about some sort of light that comes from the phones that is bad for you for your sleep. I don't know if there's science around it. Is it blue light? You can get those glasses that filter out that blue light. Do they work? What is that? What's that about? Because I think isn't that the underlying argument of if you're exposed to some sort of light during when you should be trying to sleep, it disrupts your sleep? Is there science behind that? Or is that just like YouTube stuff that I should stop watching? [LAUGHS] It's a very important question, of course. And that's why-- I know there is evidence on this. I know it has been controversial for a long time and I'm not aware of the last state of evidence on that, if it already tended to one side or not. But, of course, so the concept behind is that blue light is especially impactful on our site giver, which is like our internal nucleus in our brain that is very sensitive to light and that this area in the brain gets stimulated by blue light and then defaces our internal rhythm. And this would push our tendency to go to bed later and then driving us into more social jet lag, not being prepared to get up early. And so at what point the blue light off the smartphone in the room is detrimental or not, I'm not fully aware, but what I can say is that it's certainly a double hit in the sense that it's not only the blue light impacting your eyes and the senses behind. But also the social activity and the excitement that comes with it and the preoccupation sometimes and anxiety that might come with that and social stress. But also the new experiences that we want our adolescents to make, which are also very important for development. So when we think of how families arrange themselves in these situations, it has to happen in a way that keeps up with the confidence between adolescents and the other parts of the family. Is it only the adolescent who's vulnerable to blue light? Or is it the whole family? Are I'll be talking about adolescent's sleep hygiene or the family's sleep hygiene? That's already maybe a way to frame it differently. I like, as in like a whole family approach, because you can't, on the one hand, tell your children to not have phones in bed, and then you take your phone to bed because then yeah, I think as a child, it's probably quite difficult to hear, well, I can do this because I'm an adult and you can't because you're a child. So yeah, that whole family approach seems to-- Model the behaviour you want to see. And that is much more powerful than any discussion. It's the debate of the moment, isn't it? Jane, do you have questions about anxiety and sleep? Yes. No. Thank you. I wanted to ask about the direction of the links between anxiety and sleep? So when poor sleep may cause anxiety versus when high anxiety may cause poor sleep, can you unpack that a little bit from your paper? It was such an interesting discussion. So, based on our paper, I'm sorry to tell you, we are not able to unpack it in causal mechanisms, but we are very aware and there's a large body of evidence that it is bidirectional, bidirectional in one sense or the other. But the question is, what's the timing of each direction? And what are the moments during the day that are impactful? Like when we think of sleep impacting anxiety of the next day, is it based on the metabolic regulation of stress that acts throughout the day? And if we think in the other direction, which anxiety during the day is actually most impactful for sleep? And there are a lot of proposals that go into the pre-sleep phase. Like this, just this hour, maybe half an hour before you go to bed, what is the mental state in terms of arousal that you are in? Which is often tied to anxiety, which is often the experience that you have, your bodily experience. And so in our study, we were not able to go into this pre-sleep phase. But the directionality that we were interested in was kind of on the surface of these mechanisms. Do we get into patterns that are linked with anxiety symptoms in the end of our monitoring period? And this is where our study found more evidence into the direction that sleep can be predictive in some adolescents for less anxiety. So what I'm hearing is the relationship between sleep and anxiety is likely to be bidirectional, as in they both likely cause each other. But in your study, what you found was that you found more support for one direction, which is sleep to anxiety rather than anxiety to sleep. We didn't even compare directions, to be honest. So the question was really more in the one direction, that will certainly exist because there are experiments on this and more causally informative studies, sleep towards anxiety. Do we actually find that adolescents are different in this direction? So we went towards another level of questioning what's happening. You mentioned cognitive arousal there. So I think one of the things that I always noticed about myself compared to my friends at uni was I could never revise and do essays in the evening because I need a solid few hours-- I needed a solid few hours of just doing nothing before I could go to sleep. And even now as an adult, if I've gone out somewhere, I can't just come home and go straight to bed because there's lights and everything outside. They come home and they just sit down for a bit, do nothing, like a half an hour or an hour, whatever it is, and then go to bed. And I think that turning off those cognitive arousals to the point of I'm ready to sleep now. But I wonder what this means for young people and adolescents where they might well be working? Well, I'm being very generous. They might be working on their studies very overnight. I think a lot of young people do, and I think young people are badly characterised, a lot of young people are working a long hours. Yeah, maybe I'm being unfair, but let's just, yeah, let's just, yeah, let's assume that lots of young people are working on cognitively demanding tasks well late into the night. And then they immediately trying to go to sleep. What are the implications of what you're finding for that kind of behaviour? Well, first of all, these cognitive demanding tasks, at the end of the day or before sleeping, they might be very specific for adolescents as well. It's this big question, who am I? Who am I for my peers. What I'm going to do with my life with these wicked questions that activate us cognitively, but also emotionally? And what we found is that some adolescents, not everyone, especially those who respond with very calm mood following regular nights show less anxiety symptoms throughout the monitoring period, which was about one school year. So we found in some adolescents kind of a protective dynamic. Yeah. It's so interesting. You talked about that sleep sensitivity as well. Could you describe a bit more about that? Because I think that was interesting in terms of identifying a subgroup in there. The idea was that, up to this point, a big part of the literature does talk about the general effect of sleep being impactful on our mood or not. And that this accounts for almost all adolescents, or that's just the general effect. At the same time, we know there is this assumption that adolescents are-- not every adolescent is sensitive in the same amount towards fluctuations in sleep and perturbations of sleep. So we were interested, and if we just follow throughout the daily lives of adolescents, do we see that in the natural fluctuations some adapt differently in their daily emotional experience compared to others? And then we see that even if there's small or no effect on the group level, adolescence deviate quite a lot. So if it's really a subgroup or just a spectrum, that's not known yet. And that is also a task for us to go into different situations of life to contextualise a bit what's happening here. I'm just hypothesising, of course here. But I wonder if those individuals are sensitive to sleep deprivation or more sensitive to sleep deprivation, would they be more likely to be on the anxious side? In other words, I'm wondering, because you sometimes-- well, in my clinical work, I might have a discussion about something going wrong or something not going quite as well as one might hope, and there being a lot of anxiety about that. So if you wake up and think to yourself, well, I had five hours of sleep and I woke up in the middle of the night, that in itself might be an anxiety provoking thought. And so the sense that you feel that something hasn't gone right, and that might be articulated in a sensitivity to sleep might be related to anxiety. Would that make sense, do you think? Definitely, definitely, because that's what we see insomnia. And we know that insomnia can occur in adolescence. And already being a type of easily developing worries on different topics, that's of course inviting a lot of anxiety. And so the question is, are these dynamics more representative for these people? And probably, like we didn't touch a lot of this spectrum of dynamics, but that remains the target for our work. So that's why we go into more clinical situations right now where we know that we will find more of these reactions and dynamics in the symptoms. May I ask a final practical question, which has been-- I want to say it's been on my mind for a few years, but not really. Like as in I thought about it years ago and now the opportunity has arisen to ask the question. I saw a paper, it was definitely like early 2020s, maybe a bit earlier, where they changed school start times to that design, where in the same school, they had the regular start time. Then the following year, they changed the start time to 10:00 AM or something. And then the following year, they changed it back and they looked to see what impact it had on the young people. And I think they found that it was positive. And intuitively, that makes sense. Like if we're finding that sleep is really important during adolescence and it's disrupted potentially for lots of young people and a later school start time might well be a positive thing. I mean, I suppose a two-part question. The first part is, is the evidence there that if we changed school start times to a later time, then we'd see a positive impact on young people? And B, if it is there, is that not like one of the easiest things that we could do to improve young people's mental health? We try lots of different things, but actually, just something so structural about changing the start time for school might have such a positive impact on young people. And why don't we do it if that is the case? That's the question. You're absolutely right. The evidence is converging towards a beneficial effects in terms of absenteeism, in terms of cognitive performance, and also emotional well-being. We see even effects that where schools turn backwards to what early times and the effects reverse again. So the link is there. It's a political question which schools systems are voluntary to join the track. A few years ago, we weren't even at that point, but now we have international examples. And even in our French speaking part of Switzerland, first, public schools start shifting. And maybe the question is also to propose flexible ways that even the educational strategies can accommodate. For example, there are some schools proposing flexible hours for doing homework-- one in the morning and one in the afternoon. And the pupils, they can choose freely which one they will be present. So this way, you can accommodate different chronotypes if you like. So some students, they will prefer to be there in the morning. And other words, they will prefer to get up later and do their work in the afternoon. So this way, you even teach them being responsible for their performance. It reminds me of core hours in Zoom workplaces where you have to be connected 10:00 AM to 4:00 PM. But then 9:00 to 10:00 AM and then 4:00 to 5:00 PM, it's like you can be at home or do some other stuff or whatever. But everyone is always on 10:00 till 4:00. And I'm not advocating for that. But I'm just saying it reminds me of that where you're being flexible enough to allow for people to have slight differences. But then also for a core part of the day, everyone is doing the same thing. And it sounds like that's what you're suggesting there, where you can have a core part of the school day where everyone is together, but then the ends of either end of it, where it's flexible depending on individual differences. I suspect the difficulty because my reading of the literature-- I'm pleased to hear that that's your reading of the literature because there does seem to be fairly convincing evidence of that and certainly the adolescent stage of life. But is a problem presumably not a practical one? So teachers then would need to be starting later. And how would they accommodate other age groups? So in other words, when does it kick in? Is it in middle school? And then starting at 8:00 and going all the way to 6:00. And parents, I think, I mean, when I've had discussions with parents about this very topic, the conversation is not just about the cognitive advantages, it's practical. How do we get all the kids to school at the same time if some of them are starting at different times? But I agree with you because I think it also plays to the idea of a teenager wanting autonomy over their learning activity. And so I think there must-- presumably, there is a way around it. Maybe more is your idea of the core hours being the win. But it is interesting if the science is saying certainly one thing, it's a sitter, as you see. I think also the practicalities of it. I think something can be practically difficult and not palatable in one circumstances, but then in a different set of circumstances, you're willing to accept the practical difficulties of a given situation because the situation has changed. And I wonder whether, as a society, we are much more concerned about young people's mental health now than we were 20 or 30 years ago or [INAUDIBLE] years ago. And so now we're actually, as parents or as teachers or whatever, we're willing to be practically inconvenienced, because I think that, for the teachers, for example, or even the parents, the inconvenience would come in the practicalities bit of the timing of stuff. But then the rest of your interactions with that child might be more convenient. So it might balance out because you're not having to deal with certain things. And I think there are local examples of schools implementing certain practises that might not work everywhere. So I think there's a school up in Yorkshire or a chain of schools where you have a nine-day working week, like so a teacher only works like nine days out of 10 every fortnight. So they get a day off at some point during that time. And they've made it work for them. So I suppose maybe the way forward would be that kind of approach, where a chain of schools makes it work for them, and then it's implemented gradually in a way where it's like, oh, look, they've done it and it works for them, and this is how they've done it and then implementing it more gradually. Anyways. We can't solve everyone's problems all the time. We are not MPs. You're absolutely right. I mean, adolescents live in an adult world like adults design schooling and adults invented smartphones. So who's to blame? And who is responsible of changing? And we are surprised that even big countries like Australia are taking big decisions in terms of access to social networks? Maybe it's an indirect intervention on sleep as well. We'll see. Let's call it a day there. Thank you so much, Konstantin. That's been a fantastic conversation and one that we've been wanting to have for a long time. We've really been interested in sleep for a while. And we've just been waiting for the right paper and the right guest. And you have been that. So thank you. Thank you very much. It was really interesting. Great to be with you. I think that was such an interesting conversation. And I could feel our discussion broadening out because I suspect you felt the same as I did. The implications for this topic are so broad and so far-reaching that I think understanding this as a basic foundation to so much of mental health is going to be the theme of the future, I suspect. We try so many things as researchers to try and look at what improves young people's mental health. And I don't think sleep gets enough air time. I think what we lack with sleep is momentum. And people do policy advocacy, for sure. But I think sometimes that requires there to be a right time to advocate for something and the conditions need to be right for it. I just don't think sleep has had its moment in the policy sphere, because I think once it does, maybe it has. But once it does with young people's development, lots of things could change and they could change for the better. So that conversation that we had around changing school times, practically, it'd be difficult. But, if implemented properly, it could be really beneficial. We need more research on it, but it could be really beneficial. And maybe someone needs to have some policy makers here on this and really hammer this message home about the importance of sleep. And I just want to pick up on something Konstantin said at the end there around the social media ban in Australia. So Professor Lisa Henderson in my department at the University of York, will be leading a trial on a smartphone ban in schools to see the impact on young people's social, emotional, and cognitive development, including mental health. And the mechanism of change that she'll be investigating as part of that project is sleep. So the idea is-- the hypothesis to be tested is something about the use of smartphones that is impacting on sleep, that's then impacting on young people's development. So if we can change the interactions with smartphones by a ban, for example, what impact does that have on sleep? And then, what impact does that have on young people's outcomes. But it's a three-arm trial. And one of the arms is a bedtime ban. So it's not just like you're not allowed to go on your phones for three weeks, which is one of the arms, but it's for three weeks, we're going to see what happens if you have limited access or no access-- I'm not sure the details, to your smartphone around bedtime or a few hours before bedtime. And again, looking at the impact of sleep and then social emotional cognitive development. So it's a real live debate. And there are some very interesting projects coming on board in the next year or two. Well, they'll be starting soon. But I was going to say that's a really interesting comment as well because, and it's a perfect example of how social media is impactful, but it's somewhat distracting if you see what I mean, because it's not about social media, it's about getting a good night's sleep. And so if we ban social media or access to smartphones, that may well be helpful. But actually, it's much more useful to know what the mechanism of change is. And I think that's somewhat the problem with the social media debate. So that data sounds so valuable, it'll be fantastic. I think it's interesting about sleep, and I agree, and I don't know if it's a heuristic or if it is a true momentum in the academic literature that sleep is having its day, if you like. Because I've got an interest in the teenage brain, I have had a sort of adjacent interest in sleep, but not in the depth, obviously, that our discussion was going into. But the real-world applications are immense in terms of mental health, but also in terms of practical outcomes. So if we think about teenager;s delayed pressure to sleep, which means they want to go to bed late and get up late, it means that they're perpetually jetlagged for that 00 to 5:00 schedule. And I can't remember who it was, but it was a brilliant phrase. They said it's like a UK teenager is about a third of the way across the Atlantic all the time. And that really ubiquitous feeling of feeling horrible and feeling out of kilter is somewhat how teenagers might feel. And of course, we know that sleep deprivation has an impact on executive function, and you're much more likely to have a car crash, for example, if you're sleep deprived. That's true for us all, but particularly true for teenagers. It's actually very important to think about the cognitive value and the emotional value that is delivered with a good night's sleep. So I think it's absolutely fascinating. Shall we think about our takeaways? Well, I was really interested by the findings about the importance of regularity in sleep, as opposed to how much sleep. And thinking about those subgroups that Konstantin was talking about in terms of sensitivity to sleep. So finding about regularity about these subgroups was a really important part of that. So I think the message has got to be for working with clients, particularly who are sleep sensitive. If you don't have a sleep routine, find one. Routinize your sleep to protect your mood. And it seems to be a very strong takeaway. Mine, I'm going to cheat a bit. I don't really know what my takeaway is for academics here, but what I do have one for is parents and teachers maybe. And it comes from a conversation I was having with a friend who is a parent and a teacher. And he was talking about smartphone use and it being problematic. And I was like, well, what's the evidence for this. And I said to him, you're seeing the smartphone as the problem here, but what is the underlying thing that is being affected by the use of smartphones, according to you? And in this conversation that we've had today, you could hypothesise that it's sleep. So it's not the smartphone use, it's not the TV, it's not YouTube, it's not all of these things. It's what is then being impacted by this that is leading to poorer outcomes? So I suppose my takeaway is, what are the mechanisms? And I just encourage parents and teachers to think about, what are some of the mechanisms of change here that you think are happening? And maybe look into those because it might not be what you think. It might not be the phone, it might be sleep. OK, let's call it a day there. Join us again next week when we'll be speaking to Jamie Henson about positive affect and internalising psychopathology. [MUSIC PLAYING]