Colouring books for adults are outselling cookery books in France, and now they appear to be taking over bookshelves in the UK, too. But why?
While drawing between the lines was once reserved for children, colouring is now being used as a form of alternative therapy to help adults relieve stress and anxiety.
According to the Mental Health Foundation, 59% of adults in Britain say they are more stressed today than they were five years ago. It's no wonder we're looking for a way to feel calm.
But is grabbing the crayons the answer?
"Colouring is a great way to introduce yourself to the concept of mindfulness," Tiddy Rowan, author of The Little Book Of Mindfulness and Colour Yourself Calm tells HuffPost UK Lifestyle.
"One gets so engrossed in colouring, it’s an extraordinary activity - in fact, if you watch children playing with crayons you can see just how absorbing it is."
Tiddy believes colouring can make mindfulness more accessible to stressed adults as the action requires the mind to focus on the present moment.
"Sometimes when you’re trying to remember a fact but you can’t think of the answer, it will only come to you later when you’re doing something else entirely. Colouring can help us to experience clarity of the mind more easily," she adds.
Co-illustrator of the The Creative Therapy Colouring Book Richard Merritt agrees that colouring can provide a much needed distraction from stress, and says the experience can transport us back to easier, childhood days.
"When you’re colouring, you’re not really thinking about anything else. In that moment - when you’re sitting down with a traditional piece of paper and some pens, no apps, no noise - you almost go back to being a kid again. Colouring provides a bit of escapism.
"If you put a piece of paper and a crayon in front of a child, they’ll start drawing, but I think as an adult you lose that spontaneity," he says.
Facebook groups have been set up in response to the colouring book trend, with women (the gender predominantly taking part in the activity) coming together and sharing their stories online.
Cynthia Riviere, who administrates a Facebook group of more than 1,000 colouring book fans, spends more than an hour a day filling in the gaps of her favourite books.
She told The Telegraph: “I realised that colouring makes my headaches go away. I concentrate, my breathing slows down and I move into a deep calm.”
This sense of calm that Cynthia and may others experience when colouring may be down to the simplicity of the activity. Recent studies have shown that the majority of adults feel like they are constantly looking at a screen, and crave a slower pace life.
Both Richard and Tiddy believe the growing interest in mindfulness and alternative therapy stems from our dissatisfaction with modern culture.
"We are constantly bombarded with technology, you can download apps to your phone in a few seconds and it’s too much for us to take in. Colouring allows us to go back to a slower pace and I think people appreciate that," Richard says.
According to Tiddy, colouring can help us to reconnect with ourselves which in turn can help us reach out to those around us.
"We’re reaching out to each other on social media, but that isn't satisfying. We connect to others through a screen today, but mindfulness encourages us to live in the present moment and connect to those physically around us.
By making a few simple lifestyle changes, mindfulness is something you can begin to practice immediately - it doesn't require extensive study, expensive classes or a big time commitment.
"The interesting thing about mindfulness is that it’s got no allegiance to any spiritual or religious beliefs, it's about the self," Tiddy says. "I think that's perhaps key to the popularity of these colouring books."