Sleep encourages creative thinking, they say. But what does science say about this popular wisdom? The nocturnal rest actually helps to solve problems, studies show and there are also explanations of what the effect is based on: Deep sleep and dream sleep can therefore help us to think outside the box.
A good dose of sleep can work wonders: Overnight, tricky situations suddenly appear in a new light, the solution to a complicated problem falls like the proverbial scales from our eyes and a creative idea has planted itself in our head. The well-known advice “sleep on it first” is actually helpful – science has also proven it. “Imagine trying to solve a puzzle,” says Penny Lewis of Cardiff University. “You have all the information you need, but you are still stuck. Because to find the solution, you have to restructure the information – for example, by finding new connections between them. ”Studies show that this type of restructuring often takes place during sleep. The nocturnal rest seems to be a decisive factor in promoting creative problem-solving strategies. In short: sleep helps us think outside the box.
However, it is more difficult to answer the question of which phases of sleep are responsible for this effect: does REM sleep, which is characterized by intense dreams and rapid eye movements, play a role or is calmer non-REM sleep more important? To shed light on this, Lewis and her colleagues evaluated numerous scientific studies on the subject of sleep and creativity – and based their results on an explanatory model. It shows what could happen in the brain during both sleep stages. The result in short: Non-REM sleep helps us to organize information into meaningful categories. REM sleep, on the other hand, helps us look beyond these categories and discover unexpected connections.
Flexible pigeonhole thinking
Previous research shows that during non-REM sleep, memories stored in the hippocampus are rewound over and over again in the cortex. In this process, we notice similarities between memory contents – and this information is stored. Both areas of the brain communicate intensively with each other during this phase. Lewis and her colleagues postulate in this context: The hippocampus could specifically control what is played during sleep. Accordingly, he seems to prefer to play things that are similar or thematically match. This makes it easier for us to recognize such connections and use them to form so-called schemes. Such knowledge structures can be imagined as differently labeled drawers in a cupboard in which related things are collected – regardless of whether it is information about certain objects or concepts.
In dream sleep, however, the hippocampus and cortex do not work so closely together. Lewis and her colleagues therefore suspect that the cortex can now freely decide in which combination to play back memories. It no longer matters whether the memory contents are similar at first glance or not. Some studies suggest that so-called PGO waves activate certain areas of the cerebral cortex purely by chance. These brain waves occur more frequently during REM sleep and could trigger the playback of memories from different schemes, as the scientists report. “We know that things that occupy us appear particularly prominent in the brain and are played back more often during sleep,” explains Lewis. “Our hypothesis is based on the following: If another content is activated by chance in the cortex and this content has a similar element, a connection is established.”
Analogy between the atomic structure and the solar system
As a result, we put things together in a drawer that would not have ended up there before or only much later. These surprising connections could represent the critical creative leaps that are often so important to problem solving. The researcher illustrates this with an example: The physicist Ernest Rutherford based his famous atomic model on something that initially seems to have no relation to it – the solar system. In non-REM sleep, Rutherford’s knowledge of atoms and the solar system would have been categorized in different schemes. In dream sleep, content about atoms could have happened to be played together with content about the solar system – and the researcher could have discovered the crucial connection.
As the team points out, both forms of sleep are important. Because it is only by abstracting information according to categories that we are later able to recognize surprising structural analogies between this information. In the interplay of non-REM and REM sleep, newly discovered connections are used to restructure previously generated schemes. “We suspect: It is the alternation between the formation of schemata and the creation of connections between these schemata and other information represented in the cortex that is decisive for the complexly linked images in the brain that characterize human thinking,” said Lewis and their colleagues.
Source: Penelope Lewis (Cardiff University) et al., Trends in Cognitive Sciences, doi: 10.1016 / j.tics.2018.03.009