You feel more energetic, positive.

You know, the whole day is going to be pretty good. I think my mood goes up, doubles, you know.

I'm Marnie Chesterton, and you're listening to CrowdScience, 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.

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 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 gloomy climate by the standard of Australia, and that's what's important to remember here, Marnie. This is not by the standard of, I don't know, Scandinavia or something like that. The problem that we have here locally is the inconsistency. Summertime or 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 drop-headedness. I also lived in Sweden, and I noticed it absolutely everywhere in Sweden.

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 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 Jite 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 Alwyn, 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 a 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 achy.

My name's Tony Langham, and 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 is in England, definitely. I mean, the cold, for one thing, 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 as we're body and mind together, obviously if it's making one thing better, it's making everything better.

Tony, Alwyn 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? Or is the sun directly improving their arthritis or angina?

Well, if you're familiar with our back catalogue, you'll know CrowdScience 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 Bokenhorst. She's one of the authors of a study which analysed 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 Olwen and Tony, who say they're less achy 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 short-sleeved 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.

Oh, that is bracing.

Called Rukan.

These guys do winter differently to people in southern Spain, clearly.

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 realised 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.

We're properly sun-chasing.

You guys have come up here. Can I ask, do you live in Norway?

Yes.

We live in Oslo.

And you thought, well, 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.

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.

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 ramps, more appetite, especially sweets, weight gain, social withdrawal, and reduce sex drive.

And according to town psychologist Bjørn Berkerland, Rukan has higher levels of SAD than other parts of Norway.

The rest of Norway, we think it's about 5 to 10 percent. And in Rukan, we estimate it to 15, 16 percent.

Can you treat it?

Yes, with sun and light. It's the only method.

So he prescribes light therapies to people who have SAD.

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 travelling to the top of the mountain to see sunshine didn't quite cut it.

I moved there in 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. 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, it never dries up.

How did it make you feel?

I don't know, desperate, probably.

And 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 the 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?

Yeah.

And then nothing happens.

That's the difference between me and the others is that maybe I'm more stupid, so I just never gave up and spent my time on it.

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. Well, 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.

And it becomes a very nice spot. It's like a theatre light who comes down. It is like 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 two is flat.

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, burn me now.

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 the 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.

How do you feel about not being able to pull into this square and just get...

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 and should be.

Rukan is showing me how radically the sun can alter our behaviour. 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 round 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 organisational behaviour 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 and 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. And they found two factors were important.

The temperature and 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 city 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.