Dreaming LifeDreaming Life

REM sleep helps to make people more creative by enhancing the brain's ability to create networks of related concepts, according to a study by Sarnoff Mednick, Denise Cai and their colleagues at the University of California at San Diego.

Results of this study were published in June 2009 and appeared in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Mednick and Cai already knew that sleep enhances creativity, but they didn't know exactly what it is about sleep that makes people more creative.

They wanted to look at the different stages of sleep and see how the different stages affected creativity.

Specifically, they wanted to compare REM sleep to NREM sleep.

The researchers used a test for creativity known as a Remote Association Test (RAT). In this test, a subject is given sets of three unrelated words. They have to provide a fourth word that is related to the three words that they were given.

For example, if the subject was given the words dead, salt and deep, they could respond with the word sea.

Subjects were tested in the morning, and then again in the afternoon to see how their scores changed with time.

Some subjects rested, but did not sleep, between the two tests.

Other subjects took a nap. When they napped, their brain activity was monitored to see if they were experiencing REM or NREM sleep.

Mednick and Cai discovered that the scores of the resting group, the REM group, and the NREM group all improved when they were retested in the afternoon. There was no significant difference between the three groups.

They interpreted these results to mean that just spending some time not actively trying to solve about a creative problem (allowing it to incubate) can help you to solve it - it doesn't matter if you are asleep or awake.


Cai and Mednick then repeated the experiment using priming.

With priming, a subject is given a stimulus that encourages them to provide a particular response later.

For example, suppose someone is asked to memorize a list of names of flowers. If, later on, they are asked to think of words that begin with the letter R, they will probably think of the word Rose.

Psychologists believe that when someone is primed, a network of concepts that are associated with the stimulus (such as types of flowers) is activated in their memory.

In the second version of the experiment, subjects were given an RAT test in the morning.

They were then given a test of analogies, for example, up is to down as hard is to ----.

Half of the answers to the analogies were primes for answers on the afternoon RAT test.

This time, when the subjects were tested in the afternoon, those who had experienced REM sleep showed significant improvement compared to those who had experienced NREM sleep or who had just rested.

Mednick and Cai interpreted these results to mean that REM sleep helps stimulate the brain to form networks of associated concepts.

They believe that this could be due to changes in levels of neurotransmitters -specifically, acetylcholine and norepinephrine -in different parts of the brain during REM sleep.

Cai and Mednick say that if you are already working on a problem, just letting time pass can help you find a solution - as indicated by the results from the first part of the study.

However, if you are looking at a new problem for the first time, you need REM sleep to help you solve your problem in a creative way.