It seems millions of adults are busy coloring inside the lines.
In case you haven't heard, coloring is not just for kids anymore. Adult coloring books are one of the hottest new hobbies. According to Nielsen BookScan, sales of adult coloring books in the United States have grown from one million in 2014 to about 12 million last year.
Adult coloring books have become so popular, they've driven sales of colored pencils up 26 percent, Nielsen reports.
Mental health professionals aren't overly surprised by the trend. Experts say what used to be child's play actually makes a lot of sense for adults too.
"One of the things that I think adult coloring books can do, and there are other things that serve the same purpose, is, it pulls you out of your head into what you're doing, okay, which is a better place to be, because what you're doing is in the present, not a future that scares you, or a past that you have remorse about," said Cleveland Clinic psychologist Dr. Joseph Rock.
Rock explained that coloring provides stress relief you can't necessarily get from passive activities like watching television. The intricate patterns and colors provide distraction and make it more difficult for your mind to wander back to whatever was bothering you. Coloring also requires focus, but in a way that isn't stressful.
"They're somewhat intricate, so you have to pay attention to what you're doing as opposed to getting preoccupied with other things," said Rock.
Coloring has also become a social outlet for some, with events and clubs popping up across the country.
Finally, there's the satisfaction of seeing your finished product.
"You're accomplishing something, so when you're done you have something to show for it," said Rock.
If coloring still isn't your cup of tea, Rock says you can find similar benefits from crossword puzzles, or activities like quilting, cross-stitch, or shooting hoops in the backyard. Anything that requires focus, but doesn't add to your stress.