Your number’s up: Can you get hooked on Sudoku?

“There is a monster on the loose, and it is out to eat your brain. Pitiless in its advance and deadly in its cunning, Sudoku, a seemingly simple numbers game, has become the biggest puzzle craze to hit the world since Rubik’s Cube. It’s all over the newspapers, spreading across the Internet and heading for television in Britain, yet its phenomenal popularity raises some puzzling questions. Such as why, in a high-speed, hyper-technological age – without noticeable fanfare or promotion – would millions of people become addicted to a game invented more than 200 years ago by a blind Swiss mathematician?…Yet ominous reports pour in of ‘Sudoku seizure’. In workplaces in Britain, stories are circulating of people unable to make their children’s breakfasts, leave for the office or go to bed at night until they have solved their Sudoku” (The Telegraph of India, June 30, 2013).

In a previous blog I took a brief look at the psychology of doing crosswords. Today’s blog is arguably as frivolous as I thought I would turn my attention to Sudoku puzzles. Anecdotally I have read about people who claim to be ‘hooked’ and ‘addicted’ to Sudoku (such as a US woman – Mrs. C. Mills – who wrote about her ‘addiction’ to playing Sudoku on her i-Pad blog by Violet Njo Dicksonin her blog, and a claiming ‘I was a Sudoku addict’). There have also been various journalistic articles such as ‘Addicted to Sudoku’ in a 2006 issue of Newsweek. However, I haven’t seen any real evidence to convince me that anyone has ever developed a genuine addiction to such puzzles (although I don’t rule out that it’s theoretically possible). I certainly know a few people who spend more than a few hours a day doing Sudoku but they have the time to do them because they are unemployed or retired. In these cases, excessive Sudoku use is something clearly adds to these individuals’ lives rather than takes away from it (and on that criterion alone it is not an addiction for such individuals). According to The Telegraph [of India] news article:

“Sudoku – or something very similar to it – was invented in the 1780s by Leonhard Euler, a mathematical virtuoso from Basle. When he lost his sight in early middle age and was unable to work from books, he developed the ability to compute complex sums in his head and a talent for composing puzzles. He invented a grid-based puzzle and named it ‘Latin squares’. It was, in all material aspects, identical to Sudoku, yet it remained barely noticed until it turned up – renamed the ‘number place game’ – in America in the 1980s. It was spotted by Nobuhiko Kanamoto, employee of a Japanese puzzle magazine. The Japanese made the game slightly more difficult and renamed it Sudoku, meaning ‘number single’. Today there are at least five Japanese Sudoku magazines with a total circulation of 660,000. It began appearing in [British newspaper] The Times and has since spread to every newspaper. A mobile phone version is up and running. TV pilots are being planned. Certainly nothing comparable has been seen since 100 million Rubik’s Cubes were sold in the early 1980s”.

I’m not sure when I first came across Sudoku but I used to do (or at least try to do) the daily puzzle in The Guardian (in the days when I still read a daily newspaper).  I had certainly been doing Sudoku puzzles for a while before I did my first media interview about them. I was even more surprised when some of my press comments made it into the preface of Alan Tan’s 2007 book Sudoku for Experts. I was quoted as saying:

“Part of the appeal is that it is relatively easy to play. No mathematics involved. Once grasped, the objective is childishly simple, yet infuriatingly difficult to achieve. It looks easy. But to do it well requires real thought. The rules are fairly simple, but the scope for skill is limitless. When you solve the problem you feel terrific”.

In the article in The Telegraph, Marcel Danesi, professor of semiotics at Toronto University (and author of The Puzzle Instinct) was interviewed about the popularity of Sudoku and was quoted as saying: “You cannot find a culture, no matter how technologically primitive or advanced, that does not have puzzle traditions”. I was also interviewed for the same article and was asked if Sudoku was something we should be worried about from an addiction perspective. My only comments that made it into the article reiterate what I said above:

 “I don’t think it will be a problem as long as it remains an enthusiasm and doesn’t become an addiction. An enthusiasm gives you something. An addiction takes something away.”


I’m not aware of much scientific research on Sudoku, although in my blog on crosswords I mentioned a study led by Dr. Joshua Jackson published in a 2012 issue of the journal Psychology and Aging. The paper claimed that doing Sudoku and crosswords could change some aspects of personality among old-aged people. More specifically, they examined whether an intervention aimed to increase cognitive ability in older adults (i.e., doing crossword and Sudoku puzzles) affected the personality trait of openness to experience (i.e., being imaginative and intellectually oriented). In their study, old-aged adults completed a 4-month program in inductive reasoning training that included weekly Sudoku and crossword puzzles. They were then assessed continually over the following 30 weeks. Their findings showed that those who did Sudoku and crossword puzzles increased their openness scores compared to the control group. The authors claimed that this study is one of the very first to demonstrate that personality traits can change through non-psychopharmocological interventions.

On the same kind of theme, a non-academic article by Siski Green for the Saga website reported on how Sudoku, the card game bridge, and board games boost both body and mind. In a small section entitled ‘Sudoku to survive’ the article claimed that:

“A simple game of Sudoku could trigger the activation of ‘survival genes’ in your brain, making cells live longer and helping to fight disease. According to a study conducted at the University of Edinburgh, unused genes in brain cells are activated during stimulation like that caused by completing the puzzles. [The researchers] found that a group of these [survival] genes can make the active brain cells far healthier than lazy, inactive cells”

In my writings on the psychology of games more generally, I have noted that there are a number of key factors that determine whether games like Sudoku become firmly established or simply fade away. This includes the capacity for skill development, a large bibliography, competitions and tournaments, and corporate sponsorship. For instance, all good games are relatively easy to play but can take a lifetime to become truly adept. I would therefore argue that the capacity for continued skill development is important for Sudoku’s continued popularity and future existence. In short, there will always room for improvement. Also, for games of any complexity, there must be a bibliography that people can reference and consult. Without books and magazines to instruct and provide information there will be no development and the activity will die. The sheer number of books on Sudoku is an indication of perhaps how healthy the state of Sudoku play is.

Dr Mark Griffiths, Professor of Gambling Studies, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK

Further reading

Bennett, J. (2006). Addicted to Sudoku. The Daily Beast, February 22. Located at: http://www.thedailybeast.com/newsweek/2006/02/22/addicted-to-sudoku.html

Dickson, V.N. (2013). I was a Sudoku addict. March 13. Located at: http://christianitymalaysia.com/wp/sudoku-addict/

Green, S. Playing games for health: How bridge, sudoku and board games boost both body and mind. Saga, April 14. Located at: http://www.saga.co.uk/health/mind/health-benefits-of-playing-games.aspx

Jackson, J.J., Hill, P.L., Payne, B.R., Roberts, B.W., & Stine-Morrow, E.A. L. (2012). Can an old dog learn (and want to experience) new tricks? Cognitive training increases openness to experience in older adults. Psychology and Aging, 27, 286-292.

Mills, C. (2012). Sudoku addiction solved forever. December 9. Located at: http://claudiamillsanhouraday.blogspot.co.uk/2012/12/sudoku-addiction-solved-forever.html

Tan, A. (2007). Sudoku for Experts. Malaysia: M & M Publishers.

The Telegraph (India). Your number’s up. June 30. Located at: http://www.telegraphindia.com/1130630/jsp/sudoku/story_5123700.jsp#.Ug9dmr-9pO1