YouTube Transcript:
Is the 'sunshine cure' a real thing? - CrowdScience podcast_ BBC World Service podcast

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’s gonna be pretty good.  I think my mood goes up, it 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:
[Michael] 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.
[Marnie] 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? 
[Michael] 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.
And 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 will just tank to 16, 17.
[Marnie] Can I ask what kind of effect that has on the people in Melbourne?
[Michael] What you have is that typical,  cold-climate dropped headedness
and I also lived in Sweden, and I noticed it absolutely everywhere in Sweden,
and when the sunshine comes out, there's a little bit of warmth behind it,
the mood is better, everyone's at the café, 'Hey, mate! How you going? How's the day?'
'Yeah, great!'
[Marnie] 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?
[Michael] No, not really.
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.
[Marnie] Have you thought about moving? 
[Michael] Yeah, of course. Yeah, absolutely.
[Marnie] Is it common in Australia  for people to head to hotter parts?
[Michael] 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.
[Marnie] 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  Chite, 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 gotta 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 fybromialgia, 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 Olywn 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 certainly not as achy
- My name’s Tony Langham, and I’ve lived  here on and off for about 12 years. 
[Marnie] And you’ve got a heart condition, right? [Tony] Yes, I had stents put in last year.  
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. 
[Marnie] Do you think the weather makes a difference to your health?
[Tony] Yeah, I think it certainly does, psychologically probably, but as we’re
body and mind together obviously if it’s making  one thing better, it’s making everything better.
[Marnie] Tony, Olwyn 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.
[Anna Beukenhorst] For centuries patients have said  that there is this link between weather conditions  
and their pain, but scientists  were never able to pinpoint it.
[Marnie] Until fairly recently.
That’s data scientist Anna Beukenhorst. She is  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.
[Anna] And we found that higher humidity,  lower air pressure and stronger winds  
were significantly associated with increased  pain. So in 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.
[Marnie] 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 pains 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  
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 yet and that may also affect your mood. 
[Marnie] OK. 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? [Anna] Yes, yes, I read one interesting article,  
where they sent people from Norway to Spain to  benefit from the climate. And I think 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.
[Marnie] 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...
- Ooh, that is bracing! ...called Rjukan.
- These guys do winter differently to  people in Southern Spain, clearly.
We’ve just arrived in Rjukan and let me just say,  it’s a lot colder than it was in Spain, my fingers  
are freezing. That's partly because, for six months of the year,  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, Rjukan 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, what,  
'I'll come to the valley with no sunshine, just to feel better about how much sun there is in Oslo?!'  
- Yes that’s true, that's true.  I’ve always thought that, I mean of course,
sunshine 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.
[Marnie] Fascinating may be one way  to describe life in Rjukan,  
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…
[Bjorn Birkeland] More need to sleep, reduced  movement, more appetite, especially sweets,  
weight gain, social withdrawal  and reduced sex drive.
[Marnie] And according to town  psychologist Bjorn Birkeland,  
Rjukan has higher levels of SAD  than other parts of Norway:
[Bjorn] The rest of Norway, we think it’s 5-10%, and  in Rjukan, we estimate it to 15 or 16%. 
[Marnie] Can you treat it? [Bjorn] Yes. With sun and light. It’s the only method.
[Marnie] 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 travelling to
the top of the mountain to see  sunshine didn't quite cut it.
[Martin Andersen] I moved here 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. [Marnie] Oh, brutal! So, how bad was it? 
[Martin] 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 pushes down the cold, somehow. 
And I mean the town, it never dries up.
[Marnie] How did it make you feel? 
[Martin] I don't know... Desperate! But then I thought, why not  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  
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.
[Marnie] OK, so every generation, someone comes along and goes,
‘why don’t we do this?’ ...and then nothing happens? [Martin] And nothing happens! That’s the difference  
between me and the others, I’m more stupid and  just never gave up and spent more time on it!
[Marnie] Martin Andersen might call himself stupid, but  his proposal had a genius simplicity to it.
I arrived in Rjukan on a  sunny day. By which I mean  
you could see the bright sunshine glinting off  the mountain tops. 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 the Rjukan’s  founder had first suggested something similar -  
its now world famous ‘sun  mirrors’ were levered into place.
[Martin] The mirrors are 51 square metres all together, coming  down you get 90% of being in the direct  
sunlight. It’s three mirrors going to the  same spot. 
It's on the main square in town.
It increases and decreases during the day,
but 300-600sq m [of sun] you get. [Marnie] So, three mirrors, each about the size of a bus  
reflecting light down into the town square? [Martin] Mmm. It becomes a very nice spot,  
It’s like a theatre light which comes  down… it is like being in the sun.
[Marnie] 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 Rjukan  is looking empty and bleak...  
because this winter, all three of  Rjukan’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  co-ordinated 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.
[Martin] Now you see them. You see two are flat? [Marnie] Oh yes… is this whole square lit up by the mirrors? 
[Martin] No, no, not the whole... just in front. [Marnie] So people gather here and just  
point their faces and say, 'burn me now'? 
[Martin] 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. (laughs) Reflected sun.
[Marnie] But it’s special sun, exactly, because  
it’s reflected. I mean, is it the same sun?
[Martin] 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.
[Marnie] Can you tell me how people are reacting  to not having their winter sunshine? 
[Martin] I hope they burn cars in the  street to get it back here! (laughs)
[Marnie] How do you feel about not being able to pull into this square and get some sun?  
[Martin] I think it's 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.
Rjukan 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 just for 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 year is becoming better established.
Oscar Ybarra 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.
[Oscar Ybarra] 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, 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. [Marnie] 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:
[Oscar] 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  
study where we also looked 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. 
[Marnie] So all sorts of bits how to do with how our  brains process information seems to change,  
it seems to be affected by
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? 
[Oscar] Yes, and you have to be able to be, you  know, outside in that nicer temperature. 
[Marnie] OK. Is there a minimum amount of outside  time that you need for this to work? 
[Oscar] Sort of the breaking point  between 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  whether it will be less time than that, or more. 
[Marnie] You mentioned seasons. Is there a time of year  when this sunshine and warmth makes a difference? 
[Oscar] 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. 
[Marnie] It makes sense. If you live somewhere  that’s sunny and 19 degrees all year round,  
you kind of get used to it, I suppose. It's not a treat any more. [Oscar] 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 year!  
[Marnie] Whereabouts did you grow up? [Oscar] I was born
and raised in a little town called Alpine in West  Texas. So you asked me earlier what the weather  
was like, here in Urbana, 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. 
[Marnie] 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,  cos March in Rjukan 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 heat stroke.
And, as more parts of this planet hit 50+ degrees,  
it is worth looking at the negatives that sunshine  and heat can have on our health and well-being.
Professor Solomon Hsiang 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.
[Solomon Hsiang] We looked at studies that had been conducted 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  
favourable, you know, to people, not favourable  to agriculture, we saw higher rates of conflict,  
violence, or things you might call, you know,  the collapse of civilizations, even.
So, there's lots of different examples,  whether you look at, you know, the Maya  
in Central America, or you look at Angkor Wat,  
in South-east 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 those communities. 
[Marnie] I’m intrigued, how do you pinpoint the role of  climate in the collapse of an entire civilization? 
[Solomon] 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 neighbouring 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, 
[Marnie] 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?
[Solomon] 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.
[Marnie] 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 behaviour, 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.
[Solomon] 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, 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.
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.
And 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.
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. 
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 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.
[Marnie] 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:
[Solomon] 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 judgement, their decision  making, how their brain works. It's also possible  
that some of the effect of temperature is discomfort  
or a 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 quite a challenge. 
[Marnie] 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? 
[Solomon] I mean, that seems like it could be the case. And  one of my former students, Patrick Bayless,  
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 you know,  
our mood, like your caller asked. [Marnie] Did he establish an optimum temperature  
where people seemed to be tweeting, I don't know,  like more happy emojis and less swearing? 
[Solomon] Yeah, 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 around like 25C. 
People know when they're comfortable, and they're feeling  good. And I think that's  
what's good for the human body. I think we  all sort of have some intuition about that.  
And we try to seek it out, but that's  one reason we don't always realise, 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 realise  
that every time you get a little bit  warmer, you also get a little bit crankier.
[Marnie] So much of the research into our behaviour 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 stabilises  our mood and feelings of happiness.  
Scientists who’ve looked at how sunshine  affects the level 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 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 to feel 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.  
That's why economists like Solomon are getting involved.
Global warming will affect  our behaviours 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.
[Michael] We’ve reached the end of this week's  CrowdScience.
Today's question came from me, Michael in gloomy Melbourne.
The show was presented by Marnie Chesterton and produced by Marijke 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 [email protected]