As human beings we face an inherent contradiction. On one hand, modern humans are inherently lazy. Yet, we are driven to do something productive in life and to work in order to make a living. To do any type of work, we obviously require some initial learning. The learning never stops, as the world around us changes so quickly, that we have no choice but to constantly learn new things to survive.

A challenge arises in how to do this learning efficiently. Edgar Dale’s “Cone of Experience” model shows that only 10% of the information we read is retained in our brains. The ratio for auditory information acquisition is 20%, and for visual is 30%. The highest retention ratio comes from doing the actual work, but there are many tasks which one cannot do without first learning. Many of us would like to be able to learn effortlessly while we sleep.

Mainstream neuroscience has always believed that subliminal learning or learning while you sleep is not possible. A research report published in Nature Neuroscience in August 2012 changed this perception and has proven that subliminal learning may, in fact be possible.

A group of neuroscientists from the Weizmann Institute, together with medical researchers from Loewenstein Hospital conducted an extensive study which showed that as humans, we do indeed learn while sleeping.

Researchers were surprised to learn that during the REM phase of sleep, people had a much more pronounced capability for learning. Interestingly enough, the material which was learned during the REM phase was transitioned into the conscious mind during the NREM sleep phase.

What is fascinating about this study, is that it used odor sensation in association with hearing. These two senses were chosen because both are still active while a person is sleeping. It is believed that if an odor was present when a piece of information was stored, the same odor could serve as an effective cue to retrieve the learned information and push it into working memory when needed. The idea is not entirely new. Norwegian scientists Trygg Engen and his wife Elizabeth were founders of the psychological study of olfaction and spent over 30 years studying olfactory cognition. In 1991 Professor Engen published their results in his book “Odor Sensation and Memory”.

At the end of the 1990s, TCAT University, which was one of the largest Information Technology and computer retraining centers in the Pacific Northwest, conducted a large scale experimental study focused on career retraining using subliminal learning. This was not a controlled study, but there was clear evidence of students learning copious amounts of new material with a very high degree of success in a remarkably short time. The school used subliminal audio CDs, along with peppermint plants in all classrooms. The same peppermint plants were also present in the test center where the students were tested to prove that they had gained the knowledge. The smell of peppermint served as a cue to help students recall the information which they learned while asleep. In this case, the smell of peppermint was not associated with a single piece of information, but rather with an entire block of recently learned information.

According to Dr. Tali Shenfield of the Richmond Hill Psychology Center, subliminal learning only allows for a basic level of information acquisition that doesn’t require complex cognitive processing and integration. Despite many claims, it is yet to be proven that a person is capable to do cognitive processing of acquired information while asleep. Researchers are unable to estimate the limits for the amount of information our brain can absorb in sleep learning. It is scientifically accepted that humans only use approximately 3% of their brain, but that refers only to the part that is conscious. Subliminal learning involves our unconscious mind and we still have very little knowledge about it.