Learning While Sleeping

Though it has been disproven that humans are able to learn any kind of new information simply by being exposed to audio lessons played while they are asleep, scientists continue to study and experiment to see exactly what we are capable of learning while we are asleep.  One group of researchers has just completed an absolutely fascinating study that indicates that there is plenty that our brain can learn, even while we are not awake.  The researchers, Anat Arzi, Ilana Hairston and several other colleagues from facilities located in Israel, assembled volunteers for a series of sleep studies in which they exposed the sleeping participants to a number of external stimuli. In one study volunteers were sprayed with either a pleasant smell or an unpleasant smell while they were sound asleep. The researchers found that when the sleepers were exposed to the pleasant odor they inhaled deeply, where those who were dosed with the unpleasant odor took smaller, shallower breaths, clearly trying to minimize their experience of the bad smell even though they were asleep. Following this finding the scientists paired the different smells with different sounds. After repeating the pairings a number of times the researchers then simply played the paired sound to the sleeper without also providing the associated odor. They found that the sleepers who were exposed to the sounds that had been played at the same time as the pleasant smell responded to the sound by inhaling deeply, while the sounds that had been associated with unpleasant smells evoked the short, shallower breath. This was a clear indication that the sleeping subject’s brain had learned to expect the specific smell in association with the sound that they had heard in their sleep. The experiment was not dissimilar to the famous research done by Ivan Pavlov when he exposed his hungry dogs to food at the same time as playing a specific sound. The psychological phenomenon is called conditioning, and the Israeli researchers proved that it is possible to both learn a lesson and to evoke a conditioned response while the subject is fully asleep. Taking the research one step farther, the researchers then woke their study volunteers up and proceeded to play the same associated sounds for them. Although none of them remembered having learned anything, smelled anything or heard anything while they were asleep, when they were awake and heard the sounds associated with the different smells, they did continue to have the same response, breathing deeply upon hearing the sound associated with the pleasant smell and taking small shallow breaths upon hearing the sound associated with the unpleasant odor. The researchers involved in the study were from a variety of collaborating institutions in Israel, including the Department of Neurobiology at the Weitzmann Institute of Science, the Sleep Disorders Unit at the Loewenstein Rehabilitation Hospital and the School of Behavioral Sciences at the Academic College of Tel Aviv. The results of their experiment were published in Nature Neuroscience.