The research, published in the journal Nature, shows that new auditory memories can be formed as we sleep, although these are only laid down during particular phases of our slumber. In an experiment, sleeping subjects were exposed to white noise incorporating a recurring tonal pattern. Using electroencephalographic (EEG) and behavioral response analysis, the researchers demonstrated that subjects learned the sound patterns during cycles of REM sleep. This refers to the sleep phases characterized by rapid eye movements, which involve more dreaming, body movement, and faster breathing. Some learning also takes place during the N2 sleep phase, referring to the first unequivocal stage of sleep, during which muscle activity decreases, as does awareness of the outside world.
Interestingly, while learning is possible in these phases, in the deeper slow-wave N3 sleep, the opposite occurs. That is to say that, rather than learning, you may actually forget what you’ve learned and actively suppress memories.
“We think this suppression effect shows a core function of sleep, which is enabling the brain to forget,” Thomas Andrillon, a researcher on the project, told Digital Trends. “We are constantly forming new memories when we are awake, and there is a danger of packing the brain with memories that are costly to maintain and will clog the brain. Here we show that in the brain there are specific ways in which memories are suppressed to its advantage.”
Andrillon also points out that — even during the phases of sleep in which memories are formed — it may not be a good idea to force learning. “Stimulating the sleeping brain can have consequences on the function that sleep enables,” he said. “You may be able to learn a few words, but this may come at a cost. It could be that the cost outweighs the advantage.”
He notes that he remains skeptical of ideas like learning languages in your sleep for this reason. However, he says that there are certain types of learning which may be possible and effective: such as using REM sleep to condition smokers not to smoke.
Ultimately, there’s still much work to do in this area. Nonetheless, it’s an intriguing glimpse at the way the brain processes information — and just what is achieved through a good night’s rest.
Now we just need some smart techies to develop a sleep-tracking tool that recognizes REM sleep and gives you short, safe bursts of learning when these cycles are identified.
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