TORONTO -- After learning about the rising popularity of adult colouring books, Crystal Salamon saw an opportunity to share her longtime love of drawing with others.

Little did she know her doodling would be appreciated around the world.

"You can make one single painting and then a few people can enjoy (it). But to create drawings that you can put in a book and send all over the world, people can not only enjoy it but also use that to explore their own creativity," said the Alberta-based illustrator and art instructor, who sold 2,000 copies of her debut self-published adult colouring book within two weeks.

Salamon's success is not an isolated case.

So far this year, four of the top 10 Canadian bestsellers across all categories are colouring books -- a phenomenon unseen in a decade of charting sales, said Noah Genner, president and CEO of BookNet Canada.

"It's the kind of thing that will be given a lot as gifts, which is maybe why it's being pushed up into the bestseller list now, too," said Genner, adding that works from Scottish illustrator Johanna Basford -- including "Secret Garden" and "Enchanted Forest" -- are examples of surprise runaway hits.

"I imagine we're going to see more for a little while."

Salamon's "Awakening: Artful Colouring," first released in September, found an almost immediate audience at home and in the U.S., U.K., Australia, Brazil, France, Germany, Mexico, Norway, Switzerland and South Korea.

"I never in my wildest dreams imagined that would happen," said Salamon of the first-run sellout.

"I was thinking maybe in my biggest dreams I would sell (the first 2,000 copies) within a year.

"I've already had to other another run -- this time 5,000 -- and that just came in last week, and I'm already getting quotes for another run. It's nuts."

Salamon, a mother of two, was also unprepared for just how deeply her colouring book project would resonate as she documented her journey on her Facebook page.

Among those following Salamon's progress was a terminally ill woman from north Calgary, whose doctor had recommended that she try colouring to help manage her stress and anxiety.

"Her husband was saying when my book was published, his gift to her was to drive her out to my house so that she could meet me in person," recalled Salamon, 34, who lives in Turner Valley, Alta., about 30 minutes southwest of Calgary.

"It was just so sweet because you could tell she was quite happy and overcome. It's just so amazing.... To have the ability to use my art and my journey in a way that inspires others and can even make them happy like that -- even just for a moment by meeting me -- is pretty incredible. And pretty surprising."

The grownup colouring craze isn't just limited to books.

The co-founder of arts and crafts retailer Brika said they've "jumped on the adult colouring bandwagon" by having a wall in its Toronto pop-up shop at Yorkdale Shopping Centre devoted to doodling.

Nature-inspired wallpaper designed by Brooklyn-based artisan Jacqueline Schmidt has been reproduced as a black-and-white print on which visitors are invited to leave their colourful imprint.

"I definitely think, on the one hand, there's a throwback to childhood and the idea of taking out your pencils and crayons, and doing that is really nice," said Brika co-founder Jen Koss.

"There is a really therapeutic element to colouring.... When you get going and get into the zone and you're colouring something that's small and really intricate, I think people find it really relaxing."