It’s the latest craze. Where you might expect to see children, you find adults: They sit with colored pencils in their hands, bent over the swirls and intricate patterns of coloring books. Yes, coloring books. They are losing themselves in patterns of mandalas, curved flowers and runaway stems. This is a world they create and escape into, and it’s become a popular form of relaxation.

But how does it work? What does this pastime do to our brains to elicit such pleasure and calm?

According to clinical psychologist Scott M. Bea, Psy.D., it has everything to do with refocusing our attention. “Adult coloring requires modest attention focused outside of self-awareness. It is a simple activity that takes us outside ourselves. In the same way, cutting the lawn, knitting, or taking a Sunday drive can all be relaxing.”

What does adult coloring do to relax people?

Dr. Bea cites three reasons adult coloring can be calming:

1. Attention flows away from ourselves. A simple act, such as coloring, takes your attention away from yourself and onto the present-moment event. “In this way, it is very much like a meditative exercise,” Dr. Bea says.
2. It relaxes the brain. When thoughts are focused on a simple activity, your brain tends to relax. “We are not disturbed by our own thoughts and appraisals,” he says. “The difficulties of life evaporate from our awareness, and both our bodies and our brains may find this rewarding.”
3. Low stakes make it pleasurable. The fact that the outcome of coloring is predictable also can be relaxing. “It is hard to screw up coloring, and, even if you do, there is no real consequence. As result, adult coloring can be a wonderful lark, rather than an arduous test of our capacities,” he adds.

https://health.clevelandclinic.org/2015/11/3-reasons-adult-coloring-can-actually-relax-brain/