Though sleep scientists have long ago disproved the notion that we can learn in our sleep, that by no means that the learning process comes to a stop. Though the idea of setting ourselves to listen to a book on audiotape as we sleep will not mean that we have consumed, understood and learned the content, a recent study has shown that simple learning or classification tasks can continue even once we are asleep.
The study was a project led by Sid Kouider of Ecole Normale Superieure in Paris, in collaboration with researchers from the University of Cambridge. What they found is that simple, automated tasks such as classifying words into different categories can continue even after the subject has fallen asleep. What this means, according to the conclusions published in the journal Current Biology is that there are certain areas of the human brain that will continue to function and behave in the same way regardless of whether we are awake or asleep. This may lead to new understanding of the way that the brain works, as well as new possibilities for enhancing learning.
According to Kouider, “We show that the sleeping brain can be far more ‘active’ in sleep than one would think. Far from falling into a limbo when we fall asleep, parts of our brain can routinely process what is going on in our surroundings and apply a relevant scheme of response. This explains some everyday life experiences such as our sensitivity to our name in our sleep, or to the specific sound of our alarm clock compared to equally loud but less relevant sounds.”
The group’s research takes previous studies into subliminal processing several steps further, showing that complex tasks involving speech processing and the like “can be done not only without being aware of what you perceive, but also without being aware at all.” In analyzing their findings, Kouider indicates that the question of whether or not this can be done has less to do with the difficulty of the task itself than with whether or not the task can be presented in a way that makes the process automatic enough for the brain to continue doing it without being conscious.
The study examined EEG readings of human subjects who were directed to take different spoken words and to classify them as either animals or objects. They did this while fully awake, and indicated the classification by choosing either a button on the right for an animal classification or a button on the left for an object classification. This presentation of the question enables the scientists to identify specific markers for each type of response selection and to map the process that the brain went through in response to each category. A particular movement in the brain was clearly mapped for each word category. After the patterns were well established, the subjects were then placed into a darkened room and allowed to lay down and get comfortable. They were instructed to close their eyes while they continued to be offered the word classification task. Each eventually drifted off to sleep as the exercise was going on.
Once the subjects had fallen asleep, the scientists continued to direct the word classification task at them, though they introduced new words in order to make sure that the responses that were evoked involved actual word meaning processes. They observed the brain patterns that were exhibited by the sleeping subjects and found that their brains continued to follow the same and correct response patterns for the words that they heard when they were asleep. The responses were slower than they had been when the subjects were awake, but they were completely accurate.
This fascinating finding may be an indication that processes that can be automated in the way that the word processing was in this experiment may be able to continue even when humans have fallen asleep. An example that Kouider submits is the idea that math calculations could be read to sleeping subjects for them to indicate whether answers are correct or incorrect. Kouider believes that as long as a task can be automated it can continue throughout sleep, while tasks that cannot be automated would quickly stop as soon as the person falls asleep.
The study has generated a great deal of interest, and Kouider and his co-author Thomas Andrillon are going to delve into it more deeply, but warn that even if we are able to learn in this way as we’re sleeping, it is essential that we also think about whether that is a healthy thing for us to do. Though sleep scientists are still not entirely sure as to what the purpose of sleep is, it is clear that it has evolved over generations in the way that it has for a reason, and there is a possibility that by introducing a problem-solving process into our sleep we may interfere with the normal sleep cycle. This poses a threat to the restorative process that takes place during deep sleep, and may interrupt or prevent us from the dream state of REM sleep. The possibility also exists that by inserting a programmed, automated task into the brain we will interrupt the learning and organization process that we already know that our brains go through as we sleep. Memories are formed in the hippocampus and delivered to various areas of the cortex for long term storage, and it is during the time that we sleep that our memories become stable and extraneous information is tossed aside. By introducing new information in the midst of this process there is a real possibility that our existing memories may not be learned as easily, or even at all.