Study Shows How Sleep Can Boost Learning
Written By: Nayada Deevisetpunt
August 2, 2020
It has been long known that a good night’s sleep benefits our ability to learn new skills; however, the role of different sleep stages has been less clear to scientists. There has been some controversy and debate over the relative contributions of the REM (rapid eye movement) sleep, when most dreaming happens, and the non-REM sleep, when most dreaming does not take place.
As a result, some psychologists of the Department of Cognitive, Linguistic, and Psychological Sciences at Brown University established a study that provides important clues that could help resolve this debate. Their experiment focused on visual learning and insisted that both the REM and the non-REM stages are important for learning new skills, as both play essential and complementary neurochemical processing roles in the brain. These psychologists discovered that while the non-REM sleep restores flexibility and enhances our performance of newly acquired skills, the REM sleep at the same time stabilizes these improvements and prevents them from being overwritten by later learning. Yuka Sasaki, a professor of Cognitive, Linguistic, and Psychological Sciences at Brown University, mentioned, “I hope this helps people realize that both non-REM sleep and REM sleep are important for learning.”
Moreover, psychologists have even identified “twin benefits”, or two distinct benefits, of sleep for learning. The first benefit is what is called “offline performance gains”, which means that the learning acquired before sleep is enhanced after sleep. The second benefit is called “resilience to interference”. Which means that it protects the skills we learned before sleep from being distrurbed or overwritten by subsequent learning when we wake up. While we sleep, the brain reactivates our synapses that have been strengthened during the day and later weakens them all. By doing this, it restores plasticity (flexibility) to the brain’s wider networks, improving the overall performance. Not only this, but when we sleep, the brain also stabilizes key synapses in order to prevent what was learned on the previous day from being disrupted by new learning in the following days.
To find out when each of these processes occurs, the scientists gave volunteers a standard visual learning task. This task involved identifying letters and the orientation of lines that appear on a screen at two different times: one before and one after sleep. The participants were then allowed to sleep with their heads inside an MRI scanner for 90 minutes. The researchers used a technique called magnetic resonance spectroscopy for measuring the relative concentrations of 2 neurotransmitters: glutamate and GABA (gamma aminobutyric acid). Since glutamate transmits excitatory signals and GABA transmits inhibitory signals, neuroscientists believe that when glutamate concentrations are higher than GABA, it shows that there is an increase in neuroplasticity.
The scientists analyzed their results and found that plasticity increased during the non-REM sleep, showing an improved task performance after sleep. On the other hand, the plasticity fell to below waking levels during the REM sleep, showing a stabilization of the previous day’s learning.
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