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Girl with eyes closed happy in the sun

Curious Kids: why do I feel happier when the sun is out?

Why do I feel happier when the sun is out? – Mabli, aged 13, Barry, Wales

That is exactly the same question I asked many years ago when I was sitting on a nice sunny beach, far away on a lovely warm island. I remember thinking, “Oh gosh, tomorrow I need to fly back to rainy London where the weather is horrible. I don’t want to go; the weather will make me unhappy.”

I actually did some research into whether sunshine does make us happier. I’m a professor of economics, and I wanted to look at whether higher temperatures, more sunshine and less rainfall on a given day makes people happier. Happiness matters to economists because it is an important way of measuring quality of life. Did you know that the Office of National Statistics has been collecting happiness data for more than 10 years?

My own research has shown that while sunshine matters as a seasonal factor, it doesn’t matter much whether it’s sunny on any given day here in the UK. The sunlight you get over the course of a season is what’s important. You may generally feel a bit unhappier in the winter, but it won’t matter much whether it’s a sunny or a cloudy winter’s day.

Medically, exposure to sunlight causes your brain to produce the hormone serotonin inside your body. Hormones are complex chemicals that play an important role in regulating many of your body functions.


Curious Kids is a series by The Conversation that gives children the chance to have their questions about the world answered by experts. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.com and make sure you include the asker’s first name, age and town or city. We won’t be able to answer every question, but we’ll do our very best.


Two functions that are affected by serotonin are your mood and your sleep quality. When you’re exposed to sunlight your body will make more serotonin, which can boost your mood and make you feel better. High levels of serotonin will make you a feeling positive and full of energy.

At night, when it is dark, your body produces another hormone called melatonin. Melatonin helps your body relax and will make you feel tired. It’s a chemical produced by your body to prepare you for a good night’s sleep. A good balance between these two chemicals is very important in regulating your energy levels, giving you a good night’s rest and making you feel well during the day.

Not enough sunshine

However, for many people it is hard to balance sunlight with darkness. People who work indoors a lot, or live in parts of the world where it gets dark for a long time – like countries near the North Pole in the winter – may not get enough sunlight.

There is typically 100 times less light in a house and 25 times less light in an office when compared to a nice sunny day outside. This is why getting outside in the sun is a great way to get some exercise, enjoy the fresh air, and boost your mood all at the same time.

Three girls outside in warm clothes
It’s important to spend time outside, all year round. Prostock-studio/Shutterstock

People who live in places where there is less daylight are more likely to suffer from seasonal affective disorder (Sad). Sad is a type of depression that often occurs in the autumn and winter.

People with Sad may experience symptoms such as low energy, sadness, sleep problems, and a decreased interest in activities they normally enjoy. The most common treatment for Sad is light therapy where you sit underneath bright artificial lights for some time. This mimics sunshine and will trick your body into creating serotonin.

We need the light

However, there is more to sunlight than just hormones. Your skin produces Vitamin D from sunlight and this is important for strong bones and being healthy. From April to September most people in the UK make enough Vitamin D from sunshine alone. In the winter, though, you won’t get enough from sunshine, which is why the UK government recommends that everyone should consider taking vitamin D supplements in the autumn and winter.

There is also an evolutionary component. Human eyesight is designed for daylight. We don’t have good night vision like cats. A long time ago in the past, when we didn’t have streetlamps, long periods of darkness might have made our ancestors nervous, fearful, and therefore unhappy. And while you don’t have to worry about being eaten by a lion at night any more, you may still have some of that fear from your ancestors 5,000 years ago.

Please remember that while sunlight can have many positive effects on your mood and health, it’s also important to be safe in the sun. This means wearing sunscreen, wearing a hat and sunglasses, and avoiding being in direct sunlight for too long. And never look at the sun directly. That’s super dangerous.

This article has been updated to better represent government advice on taking Vitamin D.

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