Pity the poor professional clown these days, it's hard to shake the creepy factor.

Just ask Dr. Rami Nader, the North Vancouver psychologist who often fields queries about fear, including clown phobias.

This week he got an email from a clown begging for advice about how to avoid being creepy as a wave of clown sightings from Tennessee to Toronto have been reported, with some connected to spooky or criminal behaviour.

A series of clown sightings have been posted on social media, affecting Ottawa and Halifax-area schools. In Fort Saskatchewan, Alta., Sudbury, Ont., and Gatineau, Que., there are reports of pranksters dressed as clowns frightening people.

"It is kind of sad," said Nader.

Sad because that well-meaning clown may be out of luck as fear of clowns — or coulrophobia — is a deep, rich vein, with pranksters tapping into deep primal fears that are wired into human brains.

"There's a lot of ambiguity to what is going on with a clown. They have these large exaggerated facial expressions. So there is a painted-on smile. People know that nobody is happy all the time. So what exactly is going on? What exactly is a clown thinking?" said Nader.

Paulo Arledan clown flickr

The instinctive reaction to clowns is that the paint, mask and fake smile hide something potentially dangerous. (Paulo Arledan/Flickr)

It is the reason even infants balk at a strange clown face as the fear stems from an instinctive hard-wired reaction to the unfamiliar — and to human faces that are "unknowable."

Human brains evolved to recognize patterns and clowns break those patterns, cueing our brains before we even register that something is "off" about the character in the big red shoes.

Especially a clown who appears suddenly out of context — in an empty street, in a forest.

Gatineau clown in Parc Limbour

A man wearing a clown mask frightened children in Gatineau, Que.'s Parc Limbour on Monday, Oct. 3, 2016. (Facebook)

Coulrophobes — people who have developed a phobia of clowns — shiver at the sight of an increasing number of smiling spectres popping up on social media.

The evil clown

So how did clowns, employed to entertain toddlers, turn into horror icons?

One may point to 1970s serial killer John Wayne Gacy — who worked children's parties as a clown named Pogo, while in his off-time lured boys to their deaths and caused controversy with his prison clown paintings.

DM Pranks scary clown

Italian trickster Matteo Moroni is the filmmaker behind the hit viral YouTube channel DM Pranks. In this picture a creepy clown stares at a driver after pouring a liquid around his car. (YouTube)

Or the penultimate clown spectre named Pennywise in Stephen King's 1986 novel, It.

"It's part of the lore of the fearful, scary, evil clown," said Nader.

But the fear and distrust is deeper, and older, as Charles Dickens first depicted a drunken clown, bedraggled and bankrupt in the back alleys of the Pickwick Papers.

Even jolly birthday party clowns put people on alert — they are mischievous: Watch out they might squirt you with their flower, while smiling at the same time.

Gags the Green Bay Clown

News about a clown seen carrying four black balloons in Green Bay, Wisconsin, went viral around the world. Filmmaker Adam Krause later admitted it was part of a marketing campaign for a short horror film. (Facebook)

"You know they have this facade of emotion that's fake and not real. But you don't know what's going on underneath it," said Nader.

Adults, believing clowns were fun, used them to hawk fast food, and even decorate children's wards in hospitals until a 2008 U.K. study of children confirmed most disliked clown pictures.

Now real clowns are mortified by the rising panic.

They are hitting back on Twitter with #realclownsareaboutlove, frantic to redeem the benevolent birthday party icon associated with charity work, such as Clowns without Borders.

While many people are repelled by clowns, few seek help for their phobias.

"We live in a society where you don't really have to interact with clowns very much," Nader said.

He's confident, however, that the clown pranks will fade after Halloween, but remains troubled by the psyche of people who see the cruel shock of terrifying people as fun.

"We tend not to think of psychological injuries or harming in the same way. You can't possibly slap them in the face — [but] It's OK to scare somebody silly."