Returning from the Christmas holidays it seemed as if the whole of twitter and his dog had a shiny new adult colouring-in book except for me. With the help of Huck & Pucker, we quickly put that right, and by 5th January, there I was: sat on my sofa on a Friday night colouring away in ‘Keep Calm and Colour for Mums’ – a hobby which will apparently help relaxation, combat stress and improve concentration.

It’s not just the twitterati who were gifted these therapeutic books, the adult colouring book craze has swept across the world. Toronto charity Story Planet charge customers $10 to colour, chat, and mingle in their shop for an evening. The events are selling out fast.

Even IKEA has jumped on the bandwagon. You can now colour-in minimalist Swedish furniture from the comfort of your sofa. The images include everything from kitchenware to sofas, from potted plants to light fixtures. For those of you who find DIY quite stressful, this might be the perfect antidote after an afternoon of wedging screws into holes that don’t seem quite big enough.

Publishers and booksellers have benefited from the craze, with demand driving up book sales by 2% at WHSmith this Christmas for the first time in over 12 years. Business isn’t limited to the physical book space, with Touch Press releasing a colouring-in app from author Millie Marotta, just two weeks ago. There are even young bloggers reviewing colouring-in books, in order to raise awareness of mental illness.

Despite all of this, some question the supposed stress relieving qualities of colouring-in books. In Canada, a recent clinical study run over the course of three days, found that participants’ stress levels actually increased by 40 per cent while they were colouring. Levels of adrenaline, cortisol and noreprinephrine, the three major stress hormones, increased during the study.

Dr. Renne Lynch, the leading researcher for the study, said that the stress increases she saw in the participants of the study were unhealthy. “When the body releases these hormones, it can be harmful, especially when you’re trying to relax”.

Another study, led by Newcastle University, showed quite the opposite. It found that art therapy has greater benefits than puzzles and exercises when it comes to improving memory function. Engaging the brain in new and creative ways may be the key to a sharper ‘younger’ mind. With this in mind, Orion has published: ‘Draw your way to a younger brain’. It contains 30 intricate line drawings of safari animals, with space on the opposite page for copying. On completion, there’s even the opportunity to colour them in.

Dr. Who fans will know that there’s no full series this year – there is a colouring-in book though, and a Doctor Who-themed dot-to-dot book. Not quite the novel experience fans are accustomed to. Is the colouring-in book here to stay? The verdict remains unclear.