Today’s coloring books aren’t for kids — they’re for grownups trying to combat stress.

ana lense larrauri

Sharpen your colored pencils and take the caps off your gel markers. There’s a new — and yet still old-school — way to de-stress.

It goes like this: You color. In books.

OK, so there’s nothing new about coloring someone else’s illustrations — you’ve been doing it since you were old enough to grasp a crayon. But what’s remarkable is the steadily rising popularity of coloring books for adults (as opposed to adult coloring books, which as you might imagine are a completely different, more prurient endeavor).

Amazon counts coloring books for adults among its top sellers: At this moment, there are four in the top 10, including British illustrator Johanna Basford’s popular Secret Garden and its follow-up Enchanted Forest, published earlier this year. Secret Garden has sold more than 1.4 million copies and has been published in 28 foreign editions, and there’s no reason to suppose Basford’s next book — Lost Ocean, due out Oct. 27 — will fare any differently.

There are even travel-sized books for those on the go, like Emma Farrarons’ The Mindfulness Coloring Book (The Experiment, $9.95), which fits handily in a purse or backpack. And the trend isn’t merely American. In Brazil, according to digital news outlet Quartz, coloring books accounted for more than 17 percent of all book sales between April 20 and May 17. Pop culture has also taken notice: This fall, Bantam is publishing a Game of Thrones-themed coloring book, with 45 illustrations overseen by author George R.R. Martin. (One imagines that coloring in this book will be a lot less relaxing than spending time shading in Basford’s tranquil gardens; maybe buy a few extra red markers).

“The current popularity of adult coloring books certainly helped make this project possible,” says David Moench, a Bantam publicist working on the project. “And since we already knew that George Martin’s world inspires such wonderful art, this was an easy match to make.”

The trend shows no signs of slowing down.

“We keep thinking it’s going to end, but it’s getting bigger and bigger,” says Jeannine Dillon, editorial director at Quarto Publishing Group and creator of the Zen Coloring Book series, which includes Color Me Calm and Color Me Happy (Color Me Stress-Free arrives Sept. 15). “When we first published last October, we went with modest numbers, and the first printing was sold out. We reprinted, then had to reprint again.” In the nine months since publication, both books have returned to press a dozen times each and sold half a million copies so far.

“When I first pitched the books, it was very much a personal project for me; coloring with my son felt really relaxing,” Dillon says. “Now people are writing and telling us how the books have helped them. We’ve heard from patients going through chemotherapy. … Some cancer treatment centers have asked for printed pages to hand out to people. We get letters that have been wonderful to get.”

Lacy Mucklow, the art therapist who co-wrote Color Me Calm and Color Me Happy with artist Angela Porter, had previously used mandala designs — a spiritual symbol often found in Hinduism or Buddhism — in work with her patients. Pre-made designs are helpful because some patients freeze when asked to draw something of their own, she says.

“When there’s a session that’s agitating or difficult, or they’re dealing with traumatic stuff and need to calm down and refocus back into the present time, the coloring always does a good job,” she says. “With the more detailed designs, you really have to focus your mind and be in the present. There’s a meditative quality to it, repetitive motion. You use both sides of your brain. The right brain, the creative side, you use to pick out colors. The left side, the analytical side, you use to figure out how to negotiate the image, decide what kind of pattern you want to use. That helps people relax. Seratonin is released, and when that’s released, calm happens.”

Angel Rivera, a licensed care social worker at Baptist Health Primary Care, also uses coloring as a technique for working with patients.

“I’ve worked with geriatric patients and patients with head traumas, and we look at this as a definite modality — even to address people with early onset dementia,” he says. “There are findings that say even the geometric shapes can help a person kind of disconnect in the here and now. ... Patients who suffer depression can also benefit from this type of therapy. Coloring gets their thought processes off what makes them feel depressed, and it increases seratonin, so that’s a benefit, too.”

But for most folks, coloring books perform a simple task: They allow you to relax and forget what stresses you out.

“I think a huge part of what’s making them so popular is that it’s such an absorbing, relaxing activity,” says Millie Marotta, illustrator of Animal Kingdom and the upcoming Tropical World, due out in September from Lark Crafts. “It’s easily accessible. You can spend five minutes or five hours, depending on your schedule. It’s an engaging activity that makes you focus your mind on what you’re doing, so it’s easy to switch off your mind from everyday worry and stress. … We all did it as children, so it’s familiar and comfortable.”

Marotta, who’s already at work on her third book, also thinks the appeal is stepping away from the demands of the digital world, at least temporarily.

“It’s been a great way for people to get away from computer screens, iPads or whatever,” she says. “We spend so many hours of our lives these days glued to a screen. It’s nice to see people step back into something more hands on.”

And those who are truly ambitious need not limit themselves to simple mandalas. Steve McDonald’s Fantastic Cities (Chronicle, $14.95) features intricate urban landscapes for the truly devoted. McDonald says he had been doing the detailed drawings of cities for years, showing buildings from different vantage points, and wound up with a big archive of line drawings that had no home.

“My family thought they’d be great to color, and I liked the idea they would encourage other people to be creative,” McDonald says. “It’s true they may be for the expert coloring folk. It’s intimidating, but I think there’s a niche out there for that. What’s wrong with trying something challenging?”

But whatever you decide to color has one universal benefit, Mucklow says.

“It’s an affordable way to self-soothe,” she says. “You could go to therapy, but that’s expensive. This is a cost-effective way to take care of yourself.”