You give a patient a red pill, she becomes happier. Then you give her another blue pill, she calms down.

The medicinal effect of these pills would not surprise you until you realise that in fact, the pills contain no actual medicine. There was no painkiller or stimulant in them; these pills were placebos that show the huge power that colour has to affect our minds and bodies.

Colours are everywhere in our world. We see millions and millions of colours everyday around us from the ground we walk on to the sky above us, yet we often fail to notice how much of an impact they make in our daily lives. The idea that colours affect our mood seems vaguely odd. But now, scientific research into colour is growing and it points to one thing: our perception of colour really does affect our minds and bodies. A 2004 study found that football teams wearing red were statistically more likely to win than teams in other colours. Another, in 2008, found that male volunteers shown photos of averagely attractive women on red and white backgrounds rated the women on red as more good-looking.

Each colour is considered to have a different effect or impact. This is why people have favourite colours, why restaurants are painted in specific colours and why certain shades can help anyone achieve success. Red can boost your energy. It expresses passion and draws attention to itself. Yellow often makes people feel happier but in large quantity can have an ill-tempered effect and blue is proven to bring down blood pressure and slow your heart rate which is why it is often associated with being relaxing.

If you combine the happiness of yellow and the relaxing feel of blue you get green, a very pleasing colour for many people. Green reminds us of nature and tranquillity, purple represents royalty, orange is often very friendly and white is the colour of cleanliness and purity. On the darker side of the spectrum is black which is seen as depressing and bold and even grey that can make one have a feeling of loss and sadness.

Furthermore, colour is a powerful communication tool which is tied to religious, cultural, political and social influences. Different colours mean different things in different places. This is actually important to know because without an awareness of the significance of a particular colour, you risk offending people. For example, purple is a colour of mourning in Thailand whereas in western culture, it is associated with royalty, luxury and wealth. Individual political parties are associated with one colour or another like Labour pairing with red and Conservative with blue. Green is considered to be the holy colour of Islam while Judaism is represented by the colour yellow.

And yet, while its effects on us may be profound, colour “doesn’t really exist in the world”, says Beau Lotto, a neuroscientist at University College London. Blue isn’t a property of denim or oceans, but of how our eyes interpret a particular set of wavelengths of electromagnetic radiation, which we call visible light.

It is almost magical to see how such a simple thing like colour can make a huge difference. “And that, to me, is why colour vision is wonderful,” says Lotto. “You begin looking there, and it opens up all these other questions, and reveals what the brain is trying to do.”