Walking on Sunshine: Does sunlight make you happier?

It can often feel as if the weather dictates our moods. London has begun to come alive in the spring weather as people head outside to enjoy the warmth and the light. Yet can the sun truly make us feel happier? To answer this question, researchers have investigated whether sunlight is connected with happiness and what mechanisms might explain this effect.

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Spring has come! Weather is supposedly a boring topic of conversation but I personally love to chat about the temperature. Especially in this season, as it gives me the chance to gush over the prospect of sitting out on the grass, taking walks outside at lunchtime, and going about my day without a massive winter coat weighing me down. Lifting your face to the sky, it’s as if you can feel the sunshine raise your spirits as it warms your skin. Is that sensation of happiness an illusion? Is there actually a link between sunlight and well-being?

You may have heard of Seasonal Affective Disorder (with the suitable acronym SAD), a diagnosable condition categorised by depressive symptoms that occur with a seasonal pattern (DSM-5). Unsurprisingly, patients with SAD typically experience depression during the winter months. This has prompted a variety of research questions, all with the general aim of discovering whether sunlight is truly associated with happiness.

If being in the sun makes you happy, then are people in California the happiest of them all?

It follows that if sunlight is associated with higher well-being, then people living in sunnier environments should be better off than colder climates. All those Californians must be living in sun-filled bliss, while the British sit sadly sipping their tea and watching the rain, right? As it turns out, although both people living in and outside of California believe this to be true, actual life satisfaction ratings do not differ between regions (1). In the UK, a national survey found that the happiest, least anxious people live primarily in Northern Scotland (2). This surprising finding was picked up by a baffled BBC editor who remarked, “It is clearly not the weather.” (3)

Is Vitamin D the key to happiness?

Vitamin D, sometimes known as the “sunshine vitamin”, is produced in the skin when exposed to ultraviolet B (UVB) rays. A systematic review found evidence to suggest that vitamin D deficiency is linked to depression (4). But does vitamin D deficiency cause depression, or do people with depression avoid the outdoors and therefore have lower vitamin D?

One study on students in the United Arab Emirates (UAE) found that seasonal variation in vitamin D levels was associated with depressive symptoms – in the summer. It turns out, the sun is only beneficial if you are exposed to it. In the unbearable heat of the summer months, students avoided the outdoors and therefore had higher levels of both vitamin D deficiency and depressive symptoms (5). These results seem to indicate that it isn’t the brightness of the sun that improves our mood, but the vitamin D our skin produces in response to exposure.

This also suggests that vitamin D deficiency is causally linked to depressive symptoms, rather than the other way around. Since the students did not come into contact with the sun, they had lower levels of vitamin D, resulting in higher symptoms of depression. It seems less plausible that the students all became depressed in the summer, avoided the sun, and thus became vitamin D deficient. As it happens, preliminary research even suggests that vitamin D supplements can reduce depressive symptoms (6,7). However, much more research must be done to test treatment efficacy before any definitive conclusions can be made.

Does sunshine have anything to do with serotonin?

If you’ve looked into depression you’ve likely heard of serotonin, one of the hormones linked to happiness and mood. Selective serotonin reuptake inhibitors (SSRIs) are antidepressants that increase levels of serotonin in the brain and are used to treat depression and anxiety disorders. One article that reviewed literature on how to increase serotonin in the human brain without drugs reported a link between the serotonin system and bright light (8). Serotonin levels seem to be highest during the summer, and other research has found that the production of serotonin in the brain directly increases with sunlight duration (9). Light therapy, involving the use of “sun lamps” which simulate natural sunlight, have been utilised since the 1980s (10) to treat SAD and seem to be effective at reducing depression symptoms (11). You may not have to go outside to increase your serotonin levels, as some studies find sun lamps can do it for you (12,13). Overall, it seems that sunshine and bright lights may very well be connected to the happiness hormone.

How does all this tie together?

We can live in cloudy areas and be happy, but sunshine and brightness gives us Vitamin D and serotonin! Happiness does seem to be linked to sunlight… However, I have a confession to make. I’m originally from California and although it may be blasphemy to admit, I occasionally got bored of the constant sunshine. I would look forward to the cool, autumn breeze and the changing colours of the leaves. Winter also brings its own joys. Icy air has a crisp freshness to it, and watching the rain from indoors with a blanket and mug of warm cider is my idea of peace and calm. In fact, some countries like Norway think that winter is the season to look forward to (14). This mindset shift may be one of the reasons why people living in the high north have such low rates of seasonal depression, despite the darkness of winter months (15–17).

So, what have we learned?

Great news, we don’t have to have a mass migration to California to be happy. “Jolly Old England” is not an oxymoron!

My aunt swears by her Vitamin D supplements and research is looking promising, so I don’t have to make an uncomfortable phone call and tell her to stop taking them. Of course, research is not entirely conclusive just yet and you should always consult your GP before dashing off to the nearest pharmacy.

The brightness of the sun may increase our serotonin levels, so if the sun makes you happy then feel justified in that sensation and enjoy it! Since we are approaching summer, we can all look forward to longer days and warmer weather. Science supports happiness in the sun.

The great news is, science also supports happiness in the dark. By changing our mindset to appreciate the wintertime, we may be able to mediate sadness associated with the shorter days. Do as the Scandinavians do; embrace hygge.

 

References

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