[0:03]If I'm awake to see the sun come up, it's a great start to the day. I mean, it's just clear blue sky. You feel more energetic, positive. You know, the whole day is going to be pretty good. I think my, my mood goes up doubles, you know. I'm Manny Chesterton, and you're listening to Crowds Science, the show that answers questions sent to us from all over the world. And sometimes, if we're lucky, also takes us to some of those places, which is why I'm currently enjoying some winter sunshine in Southern Spain.
[0:44]I'm here to try and find out whether the weather makes a difference to our mood and our health. Because listener Michael in Australia got in touch with this question. I would like to know why so many people at the slightest sight of sunshine and warmth, have sharply increased enthusiasm for life and their moods appear far happier. I'm wondering as to the science on whether it's actually better, health-wise, to live in a warm climate. I'd like you, Michael, to tell me a bit more about the bit of Australia that you're from, because I always think of Australia as hot and sunny. But you live in an anomaly? I think the anomaly is the southern part, particularly where I'm from in Melbourne, which is Southern um Victoria. We have an oceanic climate, which is not much different to what you guys have in London. Of course, we have greater variation with higher highs, but we also have a terribly uh gloomy uh climate by the standard of Australia. And that's what's important to remember here, Money. This is not by the standard of, I don't know, Scandinavia or something like that. And um, the problem that we have here locally is the inconsistency. Summertime, we're leading into summertime, you might have a 25, 26, 27 degree day for three days in a row, and it'll just tank to 16, 17. Can I ask what kind of effect that has on the people in Melbourne? What you have is that typical cold climate dropped headedness. I also lived in Sweden and I noticed it absolutely everywhere in Sweden. And when the sunshine comes out and there's a little bit of warmth behind it, the mood is better, everyone's at the cafe. Hey mate, how are you going? How's the day? Yeah, great. You're not just interested in mood, right? You also want to know about whether living somewhere sunny has an effect on other health conditions. Anything in particular? No, not really. I mean, I'm interested in the science as to whether it is actually factually better health-wise to base yourself in a warm climate. Or if it's in your mind and therefore you have a better existence because your mind is a little healthier because of it. I'm not sure, and I'd love you guys to answer that. Have you thought about moving? Yeah, of course. Yeah, absolutely. Yeah. Is it common in Australia for people to head to hotter parts? Extremely. You get it a lot here with people with arthritis and other conditions like that where the doctors will say to you, hey, you know, you probably really should consider living in a warmer climate. We have that option granted in this country. Admittedly, most people don't have that option, but for me, living in London with its winter gloom and unpredictable summers, it does sound tempting. I've come to the little whitewashed village of Gite in a valley in Andalusia in Southern Spain. There are golden mountains rising all around me and orange trees and olive trees as far as the eye can see, and I've got to say, it's pretty idyllic. This part of Spain, where temperatures tend to stay above 20 degrees Celsius in December, is home to loads of retired British people. And they're all convinced that the weather's responsible for their excellent health. My name's Carol. I was diagnosed with ME and fibromyalgia and had a lot of joint pain and nerve pain. When I came to live here, in Spain, the heat actually made me physically better as well as psychologically. You want to go outside more rather than in England, you feel as if you want to stay in the warmth of your home. My name is Olwyn and I've lived here for 19 years, I think. When I was diagnosed with arthritis, then it just seemed like a good idea and I talked it over with the consultant and he thought it was a good idea, so out we came. I don't know if it's just that you psychologically feel better about it when the sun's shining, or whether you really feel better. But it's certainly not as achey. My name's Tony Langham and uh, I've lived here on and off for about 12 years. And you've got a heart condition, right? I had stents put in last year, yeah. It is easier to look after your heart out here than it than it is in England. Definitely. Because it's a cold for one thing, you know, can really get to you. Do you think the weather makes a difference to your health? Yeah, I think that certainly does, yeah, psychologically, I think probably, but you know, as we're body and mind together, obviously, if it's making one thing better, it's making everything better. Tony, Allwyn and Carol all think that living somewhere warmer and drier than the UK has eased their aches and pains. But what is it that's helping? Is it the warmth from the sunshine or the extra light from a sky not blanketed in cloud? Or is it that this sunny climate is making them feel positive, which changes their mindsets about their health conditions? Well, if you're familiar with our back catalog, you'll know Crowds Science has investigated the link between weather and pain before. And we discovered that while loads of people think there's a connection, the science has been under-researched. For centuries, patients have said that there is this link between weather conditions and their pain, but scientists were never able to pinpoint it. Until fairly recently. That's data scientist Anna Beukenhorst. She's one of the authors of a study which analyzed data from around 10,000 people across the UK to try and get a clearer picture of what's going on. Participants with a range of conditions used their smartphones to report their daily levels of pain. Then the team cross-referenced that information with the precise weather data in their location. And we found that higher humidity, lower air pressure and stronger winds were significantly associated with increased pain. So on the worst possible combination, which would be a humid, windy day with low pressure, painful days were 20% more likely. And interestingly, we didn't find a link between temperature and pain or between rain and pain. That's interesting because low pressure weather tends to be stormy or cloudy and cloud means less sunshine. And yet, there's no statistically significant link between pain levels and rain or temperature. In general, people were likely to suffer just as much when it was hot. Which might sound surprising to people like Carol and Olwyn and Tony, who say they're less achey and more mobile now they've settled under the Spanish sun. But they did all mention the physical and psychological aspects of waking up to sunshine and blue skies. So could something else be going on? One option is that warm, nice weather may affect people's mood, because we saw in our study that people's mood had a strong relationship with pain, and that was even stronger than the link between weather and pain. Of course, you have a bit of a chicken and egg question. So we actually couldn't determine what came first, the bad mood, or a lot of pain. And I think if you suffer a lot of pain and all the daily living activities get much harder, yeah, then that may also affect your mood. Okay, but there is a possibility that even if you're suffering from chronic pain, there's some sort of positive mood benefit from having lovely sunny weather, and that may influence your pain levels. Yes, yes, I read one interesting article where they sent people from Norway to Spain to benefit from the climate. And I think there during the whole study period, which maybe was one month or so, they didn't see any differences, but the first couple of days, people were both happier and more pain-free than they were in their home location. Despite the lack of hard scientific evidence that hotter weather is actually better for people suffering painful conditions, something about putting folk out into the sunshine does seem to trick some people's brains into feeling less pain. Kind of like a warm placebo. Anna mentioned Norwegians who make winter trips to Spain to benefit from the Mediterranean climate. They felt happier when they first arrived. If you've ever been to Norway, you'll know it gets very cold and very dark in the winter. Some bits of the country see absolutely no sunshine for months on end. And I'm intrigued. I've got one side of the bag that's got my sandals and shorts and t-shirts, and then the other side is hats, gloves and thermals, which is how I find myself swapping the orange groves of Andalusia for a small snowy town, three hours west of Oslo, called Rukan. These guys do winter differently to people in Southern Spain, clearly.
[10:07]We've just arrived in Rukan, and let me just say, it's a lot colder than it was in Spain. My fingers are freezing. And that's partly because for six months of the year, in this valley, the sun doesn't reach the town at all. Until a few years ago, the only way people could catch any rays was to take a cable car to the top of one of the mountains overlooking the town. I'm going to take a ride to the top and find out what a difference it makes for people who live their life in the shadows. From the top of the cable car, you can look down onto the long, narrow streets blanketed in blue shade at the bottom of a valley formed by two walls of mountains. It does seem like a strange place to build a town, and yes, Rukan is relatively young, founded in the early 1900s, when an entrepreneur realized that the long waterfall coming off one of those mountains could be tapped for a hydroelectric power plant. And it was the hydroelectric company that built the cable car so that its employees could travel to the top and feel the sun on their faces. If you go to the top of the station to the viewing point, you might reach the sun maybe. You see no sun there from here? So we're properly sun chasing.
[11:27]You guys have, have come up here. Can I ask, do you live in Norway? Yes. Yeah, we live in Oslo. And you thought, what, I'll come to the valley with no sunshine, just to feel better about how much sunshine there is in Oslo. Yeah, that's true. That's true. I always thought that, I mean, of course, the sun is something you need, and you need that to survive and live. And the fact that people actually live here without it, it's fascinating.
[11:54]Fascinating may be one way to describe life in Rukan, but for many people here, the winter is pretty hard. For a start, we use direct sunshine to make vitamin D, which might play a role in regulating mood and is well known to guard against many conditions from colds to cardiovascular disease. Sunshine also plays a key role in a mental illness, sometimes called seasonal affective disorder or SAD. This form of winter depression happens when we make too much of a hormone called melatonin, which has a production process regulated by sunlight. Not enough light, and our body clocks are thrown off their regular rhythm, triggering all sorts of symptoms, including a lack of energy. More need to sleep, reduce mood swings, more appetite, especially sweets, weight gain, social withdrawal and reduce sex drive. And according to town psychologist Bjorn Berkeland, Rukan has higher levels of SAD than other parts of Norway. The West of Norway, we think it's about 5 to 10%. And in Rukan, we estimated to 15, 16%. Can you treat it? Yes, with sun and light. It's the only method. So he prescribes light therapy, which is what it sounds like, a big bright lamp to sit in front of for 30 minutes every morning to try and combat the problem. But even for people without SAD, the option of traveling to the top of the mountain to see sunshine didn't quite cut it. I moved here in uh 2002. I knew the conditions, but still it was very strange because we moved in the autumn, just when the sun started to disappear. Oh, brutal. Yeah. So, how bad was it? The first impression was quite bad. It was more the idea that the sun is disappearing. Especially in the autumn time, it's a very big difference between being in the sun and being in the shadow. Because it pushed down the cold somehow. And I mean, the town never dries up. How did it make you feel? I don't know, desperate probably. So then I thought, yeah, but why not just reflect it down to one place? And there will always be sun in this place if it's a sunny day. And then I went to the municipality and I proposed the idea, I wrote a document, and then I found out it was an old idea from 1913, was the first time. And it's been repeated a lot of times. Okay, so every generation someone comes along and goes, why don't we do this? And then nothing happens. Yeah. That's the difference between me and the others, is that maybe I'm more stupid, so I just never gave up. And that's my time with it.
[14:43]Martin Anderson might call himself stupid, but his proposal had a genius simplicity to it. I arrived in Rukan on a sunny day, by which I mean, you could see the bright sunshine glinting off the mountaintops. While Martin wanted to put some massive mirrors up there, and angle them to reflect light down into the town. And in 2013, a hundred years after Rukan's founder had first suggested something similar, it's now world-famous sun mirrors were levered into place. The mirrors are 51 square meters altogether. Coming down, you get 90% of being in the direct sunlight. So it's three mirrors who goes to the same spot. It's on the main square in town. It increase and decrease during the day, but 300 to 600 square meters you get. So three mirrors, each about the size of a bus, reflecting light down into the town square. It becomes a very nice spot. It's like a theater light who comes down. It is like you're being in the sun. At this point, you're probably wanting me to head to the town square, feel that sun on my face, and talk to all the locals I find there sunning themselves. But the town square in Rukan is looking empty and bleak. Because this winter, all three of Rukan's mirrors have broken down. To get the sunshine in the same spot as the sun's position changes, the mirrors have to undergo micro adjustments to their angles. It's all coordinated by a computer system. And sadly, that connection crashed about a week before I arrived. But Martin takes me outside anyway to look up at the mirrors and paint a picture of life in the town when they worked. Now you see them. You see uh two is flat. It's lying down. Oh! Yes, yes, yes. And one is more up. Is this whole square lit up by the mirrors? No, not the whole, just in front. In front here. So what, people gather here and just point their faces to the sun and say. Yeah, they will. They will. And a lot of tourists come here to just be in this spot. It's very funny, you drag them into a dark valley just to see the sun. Reflected sun. But it's special sun, exactly, because it's reflected. I mean, is it the same sun? No, it's just an image of the sun, but it makes a very nice contrast to the rest of the place. I call it like a smiling machine because people they come in and then everybody smiles. Can you tell me how people are reacting to not having their winter sunshine? I hope they burn cars in the street to get it back here. How do you feel about not being able to pull into this square and just get your I think it's very sad, very sad. It's a big plus to have this little spot of sunlight. When it's not there, it becomes more gloomy than it should be. Rukan is showing me how radically the sun can alter our behavior. The mirrors there act as a magnet for bringing people together at the height of winter, even for just a few minutes. They also remind them what's around the corner, spring. The residents celebrate the return of the sunshine in March with a massive fancy dress party. And that chimes with the research. While most of the studies on mood and weather are inconclusive, the importance of seeing sunshine at certain times of the year is becoming better established. Oscar Ibarra is a Professor of Organizational Behavior at the University of Illinois in the US. He was part of a team that discovered that seasonal sunshine not only makes us happier, it can also help us to think more clearly. Previous work had looked at simply associating whether it was temperature or pressure, with how people were feeling. And our approach was a little different. We thought there would be more nuance in that, what might matter more is the season, right? Because after a while, you know, if you're deep into the summer, another warm day is just not, it won't have the same effect as the first few warm days in the spring for instance. Ah, nuance, because we humans are complex. And Oscar's team thought a sunny day in the right context might have a strong effect. They designed a series of experiments to test how much of an effect seasonal differences had on mood and cognition. The temperature and the amount of sunlight have to be, I won't say just right, but compared to what they've been, you know, they have to be more agreeable. And then in addition to that, you have to be able to spend time outside in that nice weather. So specifically, what we found out is that as the weather turned nicer, especially after a Northern winter, and people got to spend time out in that nicer weather, then what you saw was, that was associated with better moods and also with better memory performance, and in that one study where we also looked at the degree to which they updated their beliefs, nicer weather as well was associated with people's willingness to update a prior belief that they had about an individual. So all sorts of bits to do with how our brains process information seems to change. It seems to be affected by a kind of a mixture of this sweet spot of it's got to be the right temperature, it's got to be warmer than it had been. Is there anything else I'm missing? Yes, and you have to be able to be outside in that nice, certain temperature. Okay, is there a minimum amount of outside time that you need for this to to work? Sort of a breaking point between you know, where you started seeing benefits versus no benefits was around 30 minutes. It's unclear whether depending on just exactly where you were in the season if it would be less time than that or more. You mentioned seasons. Is there a particular season? Is there a time of year when this sunshine and warmth makes a difference? What we showed in the studies is that it's really coming out of the cold, winter season that you see these benefits, so once you start transitioning into the spring and summer. And that's related to this idea that there is a sense of novelty associated with it, and what is it that in a sense represents the largest change from where you've been? It it makes sense, if you live somewhere that's sunny and 19 degrees all year round, then you kind of get used to it, I suppose. It's not a, it's not a treat anymore. Yes, yes, yes, it's not a treat anymore, and take it from somebody who grew up in a place that had more than 300 days of sunshine every, every year. Where, whereabouts do you grow up? I was born and raised in a little town called Alpine in West Texas. It's sunny all the time. So you asked me earlier what the weather was like here in Urbana and I said it was cloudy. Sometimes I don't mind the cloudy days, still. After this winter, I'm sure I will enjoy the nicer weather, but, you know, too much of something can become oppressive. So it really doesn't need to be all that hot for us to experience mood and cognitive benefits. We just need a shift from colder to warmer. So a change of season like spring, like they have in Norway. That reappearance of the sun seems to be more important than how much heat it's giving off, which is lucky, because March in Rukan is still pretty chilly. The sweet spot seems to be around 20 degrees centigrade, and even that needs to not be a constant, because we quickly start taking any weather pattern for granted. Of course, too much sunshine can also cause all sorts of other problems, like skin cancer and heatstroke. And as more parts of this planet hit 50 plus degrees, it is worth looking at the negatives that sunshine and heat can have on our health and well-being. Professor Solomon Shang is Director of the Global Policy Lab at the University of California Berkeley. And has found evidence dating back 10,000 years that high temperatures can actually be really harmful for how we humans behave. We looked at studies that had been conducted, you know, around the world. And what we saw was a repeating pattern where when the climate in the historical record shifted to conditions that were not so favorable, you know, to people, not favorable to agriculture, we saw higher rates of conflict, violence, or things you might call, you know, the collapse of civilizations, even. So there's there's lots of different examples, whether you look at, you know, the Maya in Central America, or you look at Angkor Wat in Southeast Asia, which societies, you know, were faced with very long droughts, or extremely cold conditions, if you're very far north for a long time, or extremely hot conditions for a long time. And we see that that put a lot of stress on these societies, and to the point where in many cases, governments collapsed and that was really the end of of those communities. I'm intrigued. I mean, how do you pinpoint the role of climate in the collapse of an entire civilization? It's challenging to say that the climate was the only reason why a society broke down. In many cases, what you see is a pattern of overlapping stresses. So for example, in the case of Angkor Wat, you know, they were at war with their neighboring city for a long time. At the same time, they had to support, you know, a growing population, and then they were faced with a multi-year drought that they were trying to cope with and manage. And sometimes it just turns out to be too much. And I think we see that over and over again. Can you link that to a change in temperature in particular or is it just if it's normally somewhere that's hot and relatively arid and suddenly there's a lot of rainfall or vice versa? So when we look in deep history, it's actually much easier to track changes in rainfall. But we also see that in the modern period, temperature plays a really important role, and in particular, as it gets hotter and hotter, we tend to see it really affect how people make decisions, their mood, and their propensity for conflict. How much of a temperature rise is needed to see these effects depends on the situation. But Solomon says an increase in heat and an increase in conflict go hand in hand. So, as it gets hotter, more people engage in violent behavior, and every degree matters. You can measure this in all sorts of ways. His approach was to get students to play certain games, and then fiddle with the thermostat and watch what happened. There's a game called the Joy of Destruction. Essentially, students can destroy gift cards that they get as winnings. And they can destroy another person's winnings for no benefit of their own, you know, like they just see that the gift cards get cut up. And so this is kind of measuring how much satisfaction someone gets from watching someone else be harmed. And what we did is we put half the students randomly into an environment that was pretty cool, like normal room temperature. And half the students went into a setting in which we really cranked up the heat and made it very, very uncomfortably warm and they were in there for many hours. What we actually saw is that when the students were randomly put into the hot room, they were destroying over 10% more of the other students' assets when it didn't really help them in any other discernible way. What we take away from that is that the students were somehow enjoying destroying someone else's material goods, as a response to changes in their environment. And, and, you know, we want to be very careful here because there had been some really contentious political elections happening just before we were doing all our experiments. And one of the communities involved really felt like the election was stolen from them, and it turned out that the students that seemed to be experiencing all that frustration in the real world, some of it was carrying over into the experiment, and that was the community of students that seemed to be feeling the most satisfaction from destroying other people's assets. And so people face external frustration. You know, we have to normally try to contain that and accept those problems, but in some cases, we burst out, we, we do things that hurt other people. And what we see, I think over and over, is that higher temperatures give us a shorter fuse. We're less able to control those frustrations, and they end up coming to the surface and sometimes hurting other people. Solomon's research suggests that hotter temperatures impact how well people can deal with the stresses and strains of ordinary life. He's found gang violence and murders increase as the mercury rises. But is it that we're all getting hot and bothered and reacting more impulsively to stressful situations, or is it just the case that warmer weather means more people are likely to go outside, and more people on the streets means more opportunities to commit crimes? Solomon says it might be both. Certainly car theft rates go down when it's too cold to stand outside and break into cars. But there is a growing school of thought that heat might actually be doing something to our brains to make us behave differently. Solomon stressed that he's an economist, so this really isn't his field, but he did give me a rough summary. You know, like a third of the calories you eat get burned by your brain. So your brain gets really, really warm, it's like a computer just running all the time. And all of that heat has to go somewhere. And so it actually comes out in your jugular vein in your throat, down your neck and then spreads out to your skin where your skin then releases that heat to your external environment. And so, as the temperature around you gets hotter and hotter, your skin doesn't work as well to cool you down. And so that goes back upstream, and what you see is that your brain temperature actually goes up. And so it's possible that that is affecting people's judgment, their decision making, how their brain works. It's also possible that some of the effect of temperature is discomfort or distraction, and it just makes it harder to, you know, keep it together. And so trying to figure out, you know, which one of those things it is, is is quite a challenge. I know that our body works really hard to keep our temperatures constant, but it could be that a small change in temperature is basically making us overheat a bit like computers. I mean, that seems like it could be the case, and one of my former students, Patrick Bailis, he did this really interesting study where he basically just looked at a billion different tweets from all across the United States, and what he saw is that when it gets hotter and hotter, people tweet fewer smiley faces and more frowny faces. When it gets hotter, people swear more in their tweets. And so it really looks like something about just like how we feel about the world around us, changes as it gets warmer. It could be that our brains are just like overheating a little, or it could just be something else about our mood, like your caller asked. So, did he establish an optimum temperature where people seem to be tweeting, I don't know, more happy emojis and and less swearing? Yes, so in his case, he found that, you know, people are very comfortable at the temperatures you would expect. So, I mean, depending where you are in the world, you know, around like 25 C. People know when they're comfortable and they're feeling good. I think that's what's good for the human body. I don't, I think we all sort of have some intuition about that, and we try to seek it out, you know. But that's one reason we don't always realize, I think, how much the environment around us and the temperature affects our mood. It's very hard to be so self-aware that you realize that every time you get a little bit warmer, you also get a little bit crankier. So much of the research into our behavior and the weather is irritatingly fuzzy. Growing a human in optimum healthy conditions appears to be a lot more complicated than growing a tomato plant. Some of us claim to love the winter cold, others flourish in bikini weather. So what can I say with confidence? Serotonin is a key hormone that stabilizes our mood and feelings of happiness. Scientists who've looked at how sunshine affects the levels of serotonin we're able to process in the spring and summer, have concluded it's not about temperature, but access to daylight, and outside direct daylight, that makes a difference. But it does seem that our decision-making abilities can be affected by warm weather. After a cold spring, we're more likely to perform well on certain tasks when we've been out in the sunshine. But the heat sensitivity works two ways. Once we start feeling uncomfortable in that sunshine, when it's too hot, we become less good at problem-solving and more likely to behave irrationally. Listener Michael wondered if it's healthier for us to live in a warm and sunny climate. And it's a question which will influence billions of lives, whether we like it or not, thanks to climate change. There are certain species where an extra degree of warmth is a matter of life or death. For us, it's more subtle, but still really important. And that's why economists like Solomon are getting involved. Global warming will affect our behaviors and health, and he wants to know how. Although most of us don't have the luxury of moving elsewhere, we are uniquely positioned, as the species that does all this research, to work out how a warmer world will alter us. So we can at least face the future better prepared. Thank you to Michael in Australia for asking this question, and over to him for the credits. We've reached the end of this week's Crowd Science. Today's question came from me, Michael Guillia in gloomy Melbourne. The show was presented by Moni Chesterton and produced by Maraca Peters. If you've got something that's been bugging you, and you want the BBC team to investigate, write to them. The email address is crowdscience@bbc.co.uk.
