It's every student's dream: you put your French textbook under your pillow, wake up, and magically can conjugate every -er verb in time for the midterm without studying. In fact, researchers have found that it is possible for people to learn new things while sleeping.
In a study, published in the journal Nature, Anat Arzi from the Weizmann Institute and other researchers from Israel studied 55 participants while sleeping and awake. They chose to study a specific type of learning called classical conditioning.
Made famous by the experiments on Pavlov's dogs, classical conditioning teaches a person or animal to associate one stimulus with another. For example, Ivan Pavlov taught dogs to associate the ringing of a bell with dinnertime.
In Arzi's study, they paired certain tones with scents. The reason that they chose such stimuli was that neither would wake the sleeper; if a person woke up, it would nullify the results. The other reason that those stimuli were chosen was that it is easy to monitor a person's response to scents. If a person smells something pleasant, he or she inhales more deeply. If a person smells something unpleasant, he or she takes more shallow breaths. That response to different scents is the same whether a person is awake or asleep.
The researchers paired tones with scents that were either pleasant, like deodorant or soap, or unpleasant, like garbage or rotting meat. During the night, researchers also reinforced the conditioning partially, by only playing the tone. When hearing tones associated with pleasant smells, participants would breathe deeply. When hearing tones associated with unpleasant smells, they would take short, shallow whiffs.
Researchers then tested whether certain periods of the sleep cycle were more conducive to learning than others. In the second experiment, they divided sleep cycles into REM sleep (REM stands for rapid eye movement, and is the period during which most sleepers dream) and non-REM sleep. Then they played tones only during one period of sleep.
Interestingly, they found that the learned response was more evident during REM sleep, but the conversion of association from sleep to wakefulness only appeared when the tones were played during non-REM sleep. Researchers believe that the study has helped them understand "dream amnesia" better, or how many people forget their dreams shortly after waking up. They think that dream amnesia operates on conditioning during that period of sleep.
Though we may be a distance away from simply learning things by placing books under a pillow, Arzi thinks that we could possibly learn more complex subjects in our sleep.
Published by Medicaldaily.com