ST. CLOUD - "Adult coloring books" have become a must have item for book stores over the past year.

The books are just like coloring books children use, but with more complexity. Many have nature themes and claim to promote peace of mind through art therapy. Titles range from "Creative Cats" to "Adult Coloring Book: Stress Relieving Patterns." Others feature popular stories, anything from Harry Potter to Star Wars.

Jon Lee is the owner of Books Revisited in St. Cloud (Inside the Crossroads Center), he says the books were a hot Christmas item.

"I think the appeal is really just for stress relief. It gets you away from everything and it's a nice way for people to unplug and get away from technology."

So far this month, adult coloring books take up the entire top 10 New York Times best selling games and activities list. They've also become best sellers on websites like Amazon.

Lee says he isn't sure if the books are a trend or a long-lasting item. However, they've been such a hit recently that it's been difficult to keep some in stock.

"It could just be a throwback to when we were kids, the nostalgia of sitting down and coloring a picture. They're so much more intricate than a regular coloring book and there's really been a huge interest."

Recently, a group of St. Cloud artists noticed the trend in adult coloring books to create St. Cloud coloring postcards.