Let's be honest, nobody wants to wake up to a clown standing at the end of their bed.

And yet there are some people who will more than happily attend a circus, look at a photo of a clown without shuddering and even sit through Stephen King's IT without breaking into a sweat.

And then there are the other people – people who would rather swim shark-infested waters than spend a moment in the presence of a clown, whether in person or on television.

While the fear may sound juvenile, and something we should have grown out of during adolescence, a vast number of adults suffer from coulrophobia, 

But it turns out our phobia is far from irrational and something which psychologists assert affects at least 12 per cent of American adults.

Outlining why we're justified in our fear of those Godforsaken creatures, psychology professor at Temple University, Frank Farley, said: "They’re hiding their natural face."

"It can raise suspicion or fears," he explained. "Are we in danger? Should we be concerned to be in the presence of the individual?”

But if that was the case, we'd all be reduced to sniffling messes in the presence of a motorcyclist, so what gives?

Well, further to the concealment of their natural faces, many of us aren't so keen on their make-up.

"They are still recognisable – two eyes, a nose, a mouth, for example, but these features are exaggerated," he continued. "That's actually the basis for a lot of fear — the uncanny moment, where things look both familiar and unfamiliar."

And then there's that endless, unnerving smile, right?

Clinical psychologist, David Kupfer, explains: "If someone smiles at you all the time, you don’t trust them. I wonder when I see a clown face what is behind that face."

"I probably suspect that there is something not so smiley or something potentially harmful behind that happy, unrealistically happy, face." he added.

Yup, nailed it.