Sleep has often been associated with creative insights, but its role in the process has remained unclear. A new study into the effects of napping suggests that rapid eye movement (REM) sleep may help the brain to create associations between unrelated ideas, enhancing creative problem solving.
Researchers led by Sara Mednick, an assistant professor of psychiatry at the University of California, San Diego, tested 77 people using a creativity task called the Remote Associates Test (RAT). After taking the test, study participants were randomly assigned to take a nap or to rest quietly without sleeping. Those who napped were further divided based on whether they entered REM sleep or not. The three groups showed similar improvements upon retaking the test, indicating that the passage of time alone increased creative problem solving.
Researchers then looked at the effect of “priming” on the results. Study participants completed analogy tests after taking the test in the morning, the answers to which contained words that, unbeknownst to participants, would later appear on an afternoon test. The REM-sleep group scored significantly higher on the afternoon test than the non-REM and quiet-rest groups.
“Only the REM group was able to answer more of the questions with answers from the analogy test,” says Mednick. “They were able to take those words and generalize them to a completely different test, which is the creative leap.”
The study authors hypothesize that modulation of norepinephrine and acetylcholine that occurs during REM sleep may help incorporate information into associative pathways in the brain. Levels of these two neurotransmitters are higher when we are awake and inhibit recurrent connections in the neocortex.
The study was published in the June 8 early online edition of the Proceedings of the National Academy of Sciences.
*A shorter version of this item appears in the print edition of BrainWork.