Researchers at the University of California, San Diego School of Medicine think Rapid Eye Movement (REM) sleep may enhance creative problem solving. A study by Sara Mednick, Ph.D., assistant professor of psychiatry at UC San Diego and the VA San Diego Healthcare System, and first author Denise Cai, graduate student in the UC San Diego Dept. of Psychology, shows that REM directly enhances creative processing more than any other sleep or wake state. “We found that — for creative problems that you’ve already been working on — the passage of time is enough to find solutions,” said Mednick. “However, for new problems, only REM sleep enhances creativity.”

It appears REM sleep lets the brain make new and useful associations between unrelated ideas. Importantly, the study showed these improvements are not due to selective-memory enhancements.

Other research has looked at the role of sleep in creative problem solving, but not at underlying mechanisms such as different stages of sleep. In the research, study participants were shown multiple groups of three words (for example: cookie, heart, sixteen) and asked to find a fourth word that can be associated to all three (sweet, in this instance). Participants were tested in the morning and again in the afternoon, after either a nap with REM sleep, one without REM, or a quiet rest period.

“Participants grouped by REM sleep, non-REM sleep, and quiet rest were indistinguishable on measures of memory,” said Cai. “Although the quiet rest and non-REM sleep groups received the same prior exposure to the task, they displayed no improvement on the task. Strikingly, however, the REM sleep group improved by almost 40% over their morning performances.”