Some of the hottest books this summer are selling faster than they can be printed, but no one's buying them to see words or photos. This fad is all about coloring books, reports CBS News correspondent Vinita Nair.
Some say it's the back-and-forth movement they find soothing, others say it's about unplugging from a stressful life. While some may scoff at the idea of an adult coloring book, the global interest in the genre has catapulted it into the mainstream.
"It's almost hypnotic -- the scratching of the pencil on the page; you're creating something beautiful that you might not do under other circumstances," Jean Roberts said.
She didn't care much for coloring as a kid. Now, she does it everyday.
The best part for her is seeing the final result.
"And I look at this and I'm -- 'I did this? This is great,'" she said.
Last April, Roberts posted a message on Facebook inviting other adults to color with her. That led to the creation of the Cornwall Coloring Club, a monthly group that sips, shades and socializes. The goal is to unplug from the digital and immerse in the analog.
Luanne Lindemann joined, then she asked her best friend Lynn Rhodes to go with her.
"I almost feel like a lot of people have liked coloring but don't want say they like coloring ... so now we're, like, out of the closet sort of, you know."
For the past few months, adult coloring books have quietly become international sensations. This summer the genre won several top spots on Amazon's best-selling list. Some of the original and most popular books are drawn by designer Johanna Basford.
"When I was little, I would draw on books, walls, my sister, anything I could get my hands on," Basford said.
A publishing house initially approached the 32-year-old Scottish artist to draw a kids' coloring book, but she suggested something more sophisticated.
"I just felt that there was an opportunity for people to be creative and do something with their hands that was analog," Basford said. "You know, a blank sheet of paper could be quite intimidating. But with a coloring book, the outlines will be there and I wondered if people would latch onto that as a chance to sort of flex the creative muscle."
One obstacle she had to worry about though -- would it actually sell?
"With the first book, we printed an initial printout of 13,000 copies and when I saw that number, I panicked. I told my mom and I said 'You're going have to buy a lot of these books just to save face,'" Basford said.
So far, she has sold nearly 5 million books. Her drawings are all done by hand, sketched first in pencil and then traced over in pen.
Basford said it attracts so many because it's such an accessible activity.
"Some families are doing it together with their kids; people maybe that are recovering from illness are managing to do it in hospital; I've had a investment bankers," she said. "I think at the base of it, everybody has that little bit of nostalgia about when they used to color when they were kids."
For Rhodes, it's more than simply getting lost between the lines; coloring has helped ease her multiple sclerosis.
"I'm finding it easier to manipulate whatever I'm coloring with," she said.
She and Lindemann agree, just being able to sit and talk is therapeutic.
"My life, I'm constantly on the go and it's nice to just sit down and just relax and color," Lindemann said.
Some experts say they've found evidence that coloring does have specific health benefits. Coloring engages both sides of the brain and it's been shown to reduce blood pressure and relieve stress.