Grabbing a quick nap may not only be refreshing but may also increase your ability to solve problems creatively, according to US researchers who suggest that REM (rapid eye movement) sleep directly enhances creative processes more than any other sleep or wakeful state.

The study was the work of a leading expert on the positive effects of napping, Dr Sara Mednick, assistant professor of psychiatry at the University of California San Diego and the VA San Diego Healthcare System, and colleagues, and is published online in the 8th June issue of the Proceedings of the National Academy of Sciences (PNAS).

The researchers said their findings are important because they show that sleep, and REM sleep in particular, helps the brain to form “associative networks”.

Mednick said:

“For creative problems that you’ve already been working on — the passage of time is enough to find solutions.”

“However,” she added, “for new problems, only REM sleep enhances creativity.”

The researchers discovered that it looks as if REM sleep stimulates associative networks helping the brain to make new and useful connections between unrelated ideas, the key to creativity.

Previous studies have shown that sleep enhances problem solving, but they have not properly explored the effect of types of sleep, such as that with and without REM.

Also scientists don’t really know whether creative thinking improves after sleep because of the effect of the sleep itself or because going to sleep removes distractions and interference that can disrupt the consolidation of memory; so this study included a comparison group that did not sleep but just had quiet rest.

Mednick and colleagues used a creativity task called Remote Associates Test (RAT) where participants were shown groups of three words (for example “cookie”, “heart”, “sixteen”) and asked to find a fourth word that linked them all together (eg the word “sweet” in the example).

The participants did the test in the morning and then again in the afternoon after they had either had a nap with REM sleep, a nap without REM sleep, or spent some quiet time resting with no verbal inputs.

The results showed that the three groups performed the same on memory tests, but although the quiet rest and non-REM nap group had the same exposure to the task, their performance on the RAT test was the same in the morning and the afternoon.

But what was striking was that the nap with REM group improved their performance by 40 per cent in the afternoon compared to the morning.

“Compared with quiet rest and non-REM sleep, REM enhanced the formation of associative networks and the integration of unassociated information,” wrote the authors.

They suggested that REM sleep causes changes in the levels of neurotransmitters, or more specifically “changes in cholinergic and noradrenergic neuromodulation” in the brain and this makes new linkages between previously unlinked networks which enhances “the integration of unassociated information for creative problem solving”.

“REM, not incubation, improves creativity by priming associative networks.”
Denise J Cai, Sarnoff A Mednick, Elizabeth M Harrison, Jennifer C Kanady, and Sara C Mednick
PNAS published online before print June 8, 2009

Sources: American Diabetes Association, WebMD, National Diabetes Information Clearing House (NDIC).

Written by: Catharine Paddock, PhD