The popular computer game Duke Nukem has been used by scientists in a study to understand how sleep affects the long-term memory.

The Belgian research team from the National Academy of Sciences (PNAS) used MRI scans to understand how participants from the experiment stored spatial information from the game.

Pierre Orban, from the Liege University in Belgium, is one of the authors of the report and explained to the BBC the experiment's premise.

He said: "If you move to a new town, you have to think about where you are going.

"But with time, once you know the city, you don't have to think about your route anymore."

The experiment also set out to test the widely held theory that sleep deprivation affects your ability to hold memories.

In testing this idea, the researchers gave participants place-finding missions in a virtual city from the Duke Nukem computer game. Researchers then monitored brain activity through MRI scans while volunteers took part in the exercise.

The scans showed that an area of the brain called the hippocampus – involved in memory and directional orders – was at its most active when gamers had to retrieve memories to get to their destinations.

Mr Orban said: "If you have slept, you use a means of navigation that is less thoughtful. You somehow know that you have to turn left, or right or carry straight on.

"It looks like sleep accelerates this normal process. It looks like the memories are reprocessed during sleep."