Using sound cues, scientists have made study participants solve puzzles in their sleep. Share on Pinterest New research sheds light on the cognitive processes that occur in the brain as we sleep. In dreams, fragments of reality, imagination, and memory intermingle in timeline-agnostic narratives that make little sense upon waking. It seems to have something to do with memory reshuffling, and, indeed, studying before sleep is said to be a good way to retain information. When people choose to “sleep on” a difficult decision, it is because they know that there is a chance that they will wake up with a clearer view of the problem. Now, for the first time, researchers have been able to trigger problem-solving sleep. A summary of their findings appears in the October issue of Psychological Science.

The researchers’ hypothesis “We know that people rehearse or ‘consolidate’ memories during sleep, strengthening and reorganizing them,” says first author of the study Kristin Sanders, of the department of psychology at Northwestern University, in Evanston, IL. The hypothesis investigated in Sanders’ study began with a recognition that solving a difficult problem — and creative thinking in general — can be a function of constructing new combinations of known elements in search of a previously undiscovered arrangement that reveals a solution. Sanders and colleagues wondered if there could be a problem-solving strategy similar to the reorganization of memory during sleep. To test their suspicion, the researchers needed a way to direct sleepers’ brains toward specific problems without waking them. Fortunately, says Sanders, previous research has shown that “this natural process can be boosted by playing sounds associated with the information being rehearsed.” “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.” Kristin Sanders