A growing trend among adults, colouring books are said to help de-stress and unwind and are slowly taking off outside Europe, where the trend originated. The latest example, "Colour Therapy: An Anti-Stress Colouring Book," is out this week in Britain before heading to the other side of the Atlantic in June.

A way of passing the time and clearing one's thoughts -- during breaks from "Candy Crush," at least -- colouring books began taking off in France a few years ago and have grown increasingly popular there; among them, books by Lisa Magano have been nearly instant hits and "Secret Garden" (sold in France as "Jardin secret") by Johanna Basford was a success in 2013.

Basford's book also became a popular title in the UK, where the trend is picking up speed.

UK publishing house Michael O'Mara has put out several colouring books over the last year, selling more than 300,000 copies, and this latest, "Colour Therapy" -- which follows on from previous titles "Art Therapy" and "Creative Therapy" -- emphasizes the pastime's intended therapeutic benefits.

Colouring, claim the publishers, can lower anxiety, stabilize mood, increase attention span and serve as a sleep aid.

"Colour Therapy: An Anti-Stress Colouring Book" released March 5 in the UK, with a US release to follow on June 2.

A few other colouring books to try:

"Secret Garden: An Inky Teasure Hunt and Colouring Book" by Johanna Basford

"Outside the Lines" by Souris Hong-Porretta - with illustrations from Keith Haring, Shepard Fairey, Ryan McGuinness and others

"Colour Me Good" by Mel Elliott - spend hours colouring in the faces of Taylor Swift, Ryan Gosling, Benedict Cumerbatch and more.