Adult colouring books blew up in a big way a couple of years ago.
The Benefits Of Coloring As A Mindful Meditation - The Good Trade
Study shows adult colouring reduces symptoms of anxiety and depression
Doodling To Improve Your Mental Health – Forbes Health
Adult coloring helps soothe mental stresses
3 Reasons Adult Coloring Can Actually Relax Your Brain
Does Coloring Really Reduce Anxiety?, by Rebecca Cooper, PsyD, Invisible Illness
Full article: The Effect of Mandala Coloring on State Anxiety: A Systematic Review and Meta-Analysis
Sharpen Your Pencils: Preliminary Evidence that Adult Coloring Reduces Depressive Symptoms and Anxiety: Creativity Research Journal: Vol 29, No 4
Adult coloring helps soothe mental stresses
PDF) Mandala Coloring as a Therapeutic Tool in Treating Stress-Anxiety-Depression Syndrome