A new study warns that too much time spent playing computer games could affect a child's performance at school.

Britain's National Children's Bureau Northern Ireland reported the results of the study. They show that too many hours spent playing games can reduce students' chances of success in school.

The National Children's Bureau explores issues affecting children and young people in the United Kingdom. Earlier this month, the group's Northern Ireland office reported the results of a study called "ICT and Me."

The research project involved more than 600 individuals between the ages of 14 and 16. It took place over a period of two years, from 2012 to 2014. It is said to be the first ever long-term study in Northern Ireland on the influence of information technology on school test results.

The study found that teenagers who played computer games less than once a week were more successful in school than those who played them twice a day or more. Forty-one percent of the students who used gaming devices two or more times a day received passing grades on school exams. That compared with 77 percent of those who rarely played the games.

The study found that social media use did not affect school performance.

Celine McStravick is the director of the National Children's Bureau Northern Ireland. She says the study showed no connection between social media and test results.

"It was clear that social media didn't have any impact. I think that's more because social media is part of every child's life. It's the way they communicate; it's the way they keep in touch with their friends."

Many parents say their children are becoming increasingly dependent on computer games. Some have compared gaming to a drug addiction. However, the study did not explore addiction. But it did suggest that computer games can cause children to stay awake late at night. Less sleep makes children tired and unable to pay attention in school the next day.

Mark Starkey is the owner of a video game arcade in London. He says another problem is that the new games are much different from older ones.

"The ability to make games, like, a lot bigger, a lot more detailed is here now. It's gonna hold their attention longer. It's gonna hold it a lot longer, because there's always, kind of, wanting to progress through the storyline. The old games they challenge your speed, your timing rather than, perhaps, your imagination."

For many years, the computer games industry has claimed there is no connection between games and addiction. But study organizers say more research is needed to establish the effect of computer-game playing on performance at school.

I'm Jonathan Evans.