Facing a problem? Sleep on it

People may actually solve a problem better if they 'sleep on it', according to a study which suggests that brain processing during sleep is helpful to daytime cognition.

The study, published in the journal Psychological Science, sheds light on information processing during sleep, as well as incubation for problem solving - why we sometimes solve a problem better after a break. "We know that people rehearse or 'consolidate' memories during sleep, strengthening and reorganising them," said Kristin Sanders, first author of the study and a doctoral student at Northwestern University in the US.

"It's also known that this natural process can be boosted by playing sounds associated with the information being rehearsed," Sanders said. The researchers hypothesised that rehearsing unsolved problems during sleep would help people refine their memories of the problems, and improve their chance to solve them the next day. In the study, people attempted several puzzles in the evening while listening to specific sound cues.

While they slept, a programme presented sounds associated with half the puzzles they had failed in the evening.

The following morning participants solved the puzzles that had the associated sound cues played overnight better, compared to the puzzles that got no cues.

"This study provides yet more evidence that brain processing during sleep is helpful to daytime cognition," said Mark Beeman, professor of psychology and a senior author of the study. "In this case, if you want to solve problems or make the best decisions, better to sleep on it than to be on Twitter at 3 am," Beeman said.

The research is the first demonstration of actually improving problem solving by targeting memories for unsolved problems for extra processing during sleep. It strengthens the literature suggesting sleep reorganises memory, and suggests that problem solving may benefit from sleep due to rehearsal and consolidation of problem memory.

"Problem solving is part of everyone's daily life. While we use tricky puzzles in our study, the underlying cognitive processes could relate to solving any problem on which someone is stuck or blocked by an incorrect approach," Sanders said. However, the research may only apply to situations where people have the background information they need to solve the problem and just haven't found the right configuration yet.