Well it does, doesn’t? We all know that beautiful feeling of waking up, looking out of the window and seeing blue skies with sunshine streaming in. It puts us in a great mood straight away. Conversely, when up above you is a blanket of grey clouds, we feel pretty fed up. A funny little observation I’ve made since being in Sydney is that people here, broadly speaking, are a little more friendly and cheery than in the UK. And it really is a noticeable enough trend to be obvious. And yet much of the population shares the same ancestry, so how did that happen? The UK’s not that bad is it?

But I’m not going to spend this blog convincing you that sunshine makes us feel happy. Most of us have already had this insight and if you haven’t…well you should probably stop reading here as the rest of the blog is based on this assumption. And you’re probably living somewhere without much sunlight – like Antarctica maybe. Go and take a holiday in the Caribbean and then read it again.

Neuroscientists have identified the physiological basis of this improvement in mood that occurs when we receive more sunlight. Depending on what you read, you will hear about increases in certain chemicals called endorphins and serotonin. Both have been frequently linked to mood, and indeed the main form of drug treatment for depression is a series of drugs called SSRIs, which artificially raise our levels of serotonin. I touched on the subject in an earlier blog (linked to brain changes blog).

For most Neuroscientists, they think that this increase in chemicals is a splendid answer to the question of the title. But not for me. You see, mood is an adaptive mechanism that has evolved over time to give us a biological advantage. We have reward pathways in the brain, which exist to give us a positive feeling when we do something that is good for us i.e. anything that helps us to survive or create more mini people. Likewise they give us a negative feeling when we do the opposite. Of course there are plenty of examples where this can go horribly wrong – such as with some recreational drugs, which act very powerfully on these reward mechanisms and confuse the hell out of our bodies.

So emotion isn’t just there because it’s nice to feel happy. It has a more adaptive purpose. With that in mind, why does the sun lift our mood? Or rather, why does our reward mechanism in the brain tell us that being in the sun is AWESOME? When I connect up the dots I’m left with the conclusion that sunlight obviously has an impact on our bodies that is important for us physiologically – important for our survival and health.

The best answer I can come up with is Vitamin D. Sunlight is well known to increase Vitamin D in our bodies, a vitamin that is quite tricky to get from any other source in the same quantity as from the sun. It’s good for our teeth, bones AND does truly marvellous things for our immune system. Well that’s pretty awesome. I guess with that in mind, it would make some sense that our brain is telling us to go and soak up more of it.

The bizarre lead on then from this then, is that those of us living in countries without much sunlight and feeling miserable (typically associated with higher levels of mental illness, especially seasonal affective disorder and even higher suicide rates) are actually receiving feedback from our brains telling us to LEAVE. It’s basically saying to you, “Look, you can stay in this country with its rubbish weather where I’m not going to get any of that delicious Vitamin D I like, but I’m going to make you feel bloody miserable if you do.” If this was the most powerful driving force for humans, we would probably see a very different population density across the globe, with hoards of people moving to Latin America and the Caribbean, and no one left in Scandinavia or the UK. I don’t know what would happen to Eskimos.

So those are my two cents on the matter. Hopefully I’ll uncover more reasons why our brains have adapted to encourage us to get outside in the lovely sunshine.

And in the mean time go and listen to ‘Ain’t no sunshine when she’s gone’ by Bill Withers. It’s been in my head the whole time I’ve been writing this blog…

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