If you are stuck on an issue that requires "unconventional" solutions, indulge in the luxury of a few nights of rest. That sleep is fundamental to strengthen learning and creativity is a known fact, but the role played by its various phases is still discussed. Now a new research hypothesis, which will be declined in the next five years, proposes that REM sleep ( phase that repeats several times during the night and is characterized by rapid eye movements) and non-REM (composed of alternating light sleep phases) to periods of deep sleep) work together, and in a complementary way, to facilitate creative thinking .
HOW TO WEAVE THE CANVAS
The theory of Penny Lewis, a neuroscientist at the School of Psychology of the University of Cardiff (Scotland), is illustrated in the magazine Trends in Cognitive Sciences.
"Imagine that you already have all the memories you need, but have to restructure them - create connections between thoughts that you did not connect, integrate elements that you did not have integrated," says Lewis.
Various studies indicate that these unexpected relationships between known elements can more easily emerge after a night's sleep: Lewis has analyzed the scientific literature on the subject to elaborate a model on how the different stages of sleep contribute to the "miracle".
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Depending on the model, non-REM sleep has the task of organizing information into useful categories; that REM , to help us to see beyond these categories, to create original connections . When we fall asleep we enter non-REM sleep, which includes a lighter phase extended for much of the night, plus a deep torpor phase - slow-wave sleep - in which millions of neurons are activated simultaneously: at this stage, we do more effort to wake us up, and if it happens, we feel particularly disturbed.
Past studies have proposed that in this stage the hippocampus (a fundamental brain structure for learning and memory) reproposes the memories accumulated during the day, and when these present similarities with our previous knowledge, they leave traces in the neocortex (the outermost layer of the brain, evolved more recently, deputed to higher cognitive functions ).
In this phase, the hippocampus and the neocortex work hand in hand: according to Lewis, the former manages to control the memories to be re-proposed, preferring those thematically linked, or from the similar context, categorized with the same labels. The neocortex is therefore urged to follow these well-organized schemes.
AFTER THE ORDER, CHAOS
In the REM phase (the phase most traditionally accompanied by dreams), on the contrary, hippocampus and cortex do not seem to collaborate: both are in an extremely flexible state, in which new neural connections can be formed or in which those present can be strengthened or weakened. If in the previous phase the neurons worked as if in a "chorus", in this there is a real cacophony , in which, however, we can distinguish some unexpectedly pleasant chords.
The neocortex is free to propose memories in different combinations , regardless of similarity. It may happen that between concepts that apparently are not related to each other, as for example "Solar System" and "electrons", unexpected similarities are found: brilliant ideas are born and solutions outside the box (as, to follow the example brought by Lewis, the atomic model proposed by Earnest Rutherford, inspired precisely by the structure of the Solar System).
According to some theories, dreams are nothing but a conscious manifestation of these processes of categorization, association, revolution and transformation of memories. In essence, the brain "looks at itself" while manipulating mnemonic traces.
Some parts of the model are supported by experimental evidence, others less: the aim of Lewis is to explain as much as possible the fascinating hypothesis, so that it can be tested with scientific studies.