Learning During Sleep

Information picked up while we slumber can stay with us when we awake, even if we aren’t aware of it.

By | August 26, 2012

Alessandro Zangrilli" > Wikipedia, Alessandro Zangrilli

Israeli scientists have found the strongest evidence yet that people can learn new information while they are sleeping, rather than simply strengthening memories already made.

Anat Arzi from the Weizmann Institute of Science in Rehovot, Israel played tones to sleeping volunteers before wafting smells of deodorant, shampoo, rotten fish, or dead animals past their noses. The smells triggered a sniffing reflex and the pleasant ones drew stronger sniffs. Then, when Arzi played the tones alone, the volunteers still sniffed, and more strongly to tones that had been paired with nice odors.

This conditioned response lasted through the night and into the next morning when the volunteers woke up. Although they still sniffed when they heard the tones, none of them were aware of what they had learned.

“This work is transformative in that it shows that humans can acquire information not only without awareness but also in a non-conscious state,” says Kimberly Fenn, a psychologist from Michigan State University, who was not involved in the study.

“There’s a kind of dogma that says the brain encodes new information when it’s awake, and consolidates memory while asleep,” explained Jan Born, a sleep researcher from the University of Lübeck. “This paper shows that the contrast between these two modes of activity isn’t that sharp.”

Decades of research has already shown that the brain actively processes information while we sleep, and we can strengthen existing information with the right triggers, such as odors present at the time of initial learning. But its ability to learn while snoozing has been less clear.

Several groups have tested for advanced forms of learning during sleep, like picking up the links between pairs of words. All such experiments have failed. The only positive results came from studies showing that a very basic form of learning known as classical conditioning can occur in sleeping rats and infants, which begin to associate two stimuli—say, a tone and a puff of air—if they are presented together.

By contrast, Arzi’s experiments used a different technique called “trace conditioning,” where the tone and the smells are separated by more than a second. “This is considered a more advanced type of learning, and unlike classical conditioning, it depends on the hippocampus,” she said. “This is the type of learning associated with more complicated cognitive tasks, and therefore finding it in sleep is potentially important and novel.”

Arzi also took steps to ensure that her subjects were not inadvertently waking up. Throughout her study, a sleep technician monitored the volunteers’ brain activity and halted the experiment whenever they showed signs of rousing. All such trials were left out of the final analysis.

Arzi’s volunteers only learned a very simple response, and it is not clear if we can pick up more complex information while sleeping. “This does not imply that you can place your homework under the pillow and know it in the morning,” she said. “There will be clear limits on what we can learn in sleep, but I speculate that they will be beyond what we have demonstrated.”

Fenn agreed. “It is difficult to imagine that any form of declarative information, even simple vocabulary learning, could be accomplished in a sleep state,” she said. “That being said, this study may have strong implications for conditioning of undesirable behaviours.”

Addictions, for example, are sometimes treated by teaching people to associate the drugs they crave with something repulsive. Although such approaches are controversial, our hours of slumber could provide a prime opportunity to enshrine such associations, and the lack of awareness when we wake up would only be a bonus, Arzi noted. “If you have some bad habit that you want to get rid of, awareness may only hinder your efforts,” she said. “If you could learn to get rid of the habit during sleep, you may do it without awareness as to why.”

A. Arzi et al., “Humans can learn new information during sleep,” Nature Neuroscience, doi:10.1038/nn.3193, 2012.

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Avatar of: Moonfleet Eldai

Moonfleet Eldai

Posts: 1457

August 27, 2012

An interesting find. Since our brains solidify, in our sleep, knowledge we acquired during or waking hours and that this passes as a dogma. Here, learning while sleeping seems to suggest the possibility that an opposite mechanism can also take place.

Stories of solving equations in our sleep when preparing for math tests can probably be familiar to many of us and I suppose can indicate that knowledge solidification is in progress. If we associate smells to stuff we are studying by day and then in the night during our sleep find a way to inhale one of these fragrances can't we potentially trigger subject-guided solidification of information ?. Sounds like an Idea, a bit crazy though !

Avatar of: Free Bike

Free Bike

Posts: 1

August 27, 2012

So what If say I would like to learn a good habit ? how do I go about it ?

Avatar of: corrigible


Posts: 42

August 27, 2012

Decades ago I composed and arranged music for multiple instruments and subscribed to several magazines for musicians. (After many a twelve hour work day of composing and arranging I burned out and never since have done more than piddle with it.) One of the magazines I subscribed to back then had an article claiming that research had shown that creativity could be increased by taking control of one's dreams and, indeed, I found after much waking effort, that I could to SOME extent at least take charge of my dreams. And on at least four occasions I DREAMED a beautiful, exciting musical composition, full blown, and was able to recall it and reduce it to paper and thence to sound in a fully orchestrated piece. I could care less whether anyone believes it or not. I know that four of the works I enjoy most out of years of effort, came to me, full blown, in dreams. Each has a dreamlike quality that is difficult to describe, but that impacts others when they hear it.
Later, wishing to push this "dream business" farther, and having developed the ability to be aware that I was dreaming, I began to take notice of certain things that may interest anyone who wishes to examine dreams and dreaming scientifically. I became aware that I was unable to perform mathematics in a dream. Also, in a dream, I could read copy. However, when I would go back to reread an interesting sentence, it would not be the same and I could not remember what I had read that I wanted to reread. Naturally, in order to reread what I was dreaming, I would have had to recall an entire article or at least a paragraph. And, likewise, in doing math, I would have to recall what I had done in a problem I was "seeing" myself do in writing. And, for whatever reasons, I realized my mind could create elaborately complex landscapes, colors, sounds, music, even paintings and such, but could hold, say, an entire paragraph even as I was staring at it in a dream.
What I sought to reread, I had to recreate ver batim, and I just could not make it happen.
But I tried repeatedly to do at least some very simple addition and subtraction that required no carrying, or anything I would have to glance back at to keep it in mind. At first I literally could not add 3 plus 5, but over time I could. Multiplication past memorize tables was totally beyond me.
What scientific value has this? Who knows. I may haver read somewhere that iMRIs have been done one people dreaming. Much may have to do with what portions of the brain are active. But what mystifies me is the complex musical movements and instrumental arrangements came to me FULL BLOWN, and what landscapes in intricate detail, FULL BLOWN... that I could recall when I awakened if I were fortunate enough to be awakened while I was hearing or seeing such a full blown conceptualization.
Taking a diary, and describing a "scene" I had awakened from dreaming, I wrote for HOURS details I vividly recalled and could revisit in my conscious mind.
In recent years I have focused on some philosophical issue or some mathematical problem and have dreamed I was working on it and -- although i could not dream the activity of solving it, I DO sometimes awaken with a new insight that enables me to
go to my desk and work the problem, or think through a highly complex set of philosophical steps in thinking something through. My mind, it seemed, could more easily come through with an enormously complex process of calculation or creativity, and yet could not consciously add two to three and get five, by going through the process step by step.
Think what you will. My only purpose in sharing this is to SUGGEST some approaches to examining why a complex thing can be dreamed into solution full blown, but cannot be performed in a step by step way, more than at the simplest of levels.
Having tried memorizing such things as the periodic table of elements wearing earphones, I'm not sure that helped at all. I succeeded but also worked on the memorization when awake. It amuses me to see that one would remember something as primitive as the smell of something rotten... and have a veritable conditioned reflex derived from that. Surely, if there is learning during sleep, we could learn something calling on more brain areas that just that. Can't we? ( : > )

Avatar of: Guest


August 29, 2012

Nice. My sister is in that lab in the Weizmann institute. I would suggest to let people smell cigarette smoke immediately followed by the smell of vomit or a dead animal corpse during their sleep. maybe we can rid the world of smokers this way.

Avatar of: Eyal Yablonka

Eyal Yablonka

Posts: 1

August 29, 2012

Nice. My sister is in that lab in the Weizmann institute. I would suggest to let people smell cigarette smoke immediately followed by the smell of vomit or a dead animal corpse during their sleep. maybe we can rid the world of smokers this way.

August 30, 2012

I've bought and later made my own 'hypnosis' tapes which I played all night. I don't smoke anymore and quit drinking too.

Avatar of: Luis Henrique

Luis Henrique

Posts: 1457

September 4, 2012

I lighted hers cigarette and right after I put my shoes (which smells very, very bad) next to my wife nose for 3 weeks. Without knowing, she quit 15 years of smoking :) I'm so happy!

Avatar of: aderrah hasnul

aderrah hasnul

Posts: 2

September 23, 2012

An interesting post indeed. I never knew that humans' brains were so cool and we could actually learn new information and process them while sleeping rather than strengthening memories already made. These actually makes me wonder, if only we could just sleep for hours and hours while still be able to learn new things in school or in university. I bet the school and the university would be a quiet place instead.

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