200.000 hours. That’s the average number of hours a human sleeps in 70 years of life. Current life-style that want us more productive, would like us to exploit such potential to improve our cognitive powers. It’s not a surprise in a society that loves short-cuts to everything. It takes about 360 hours of study to a Chinese person to be able to have an acceptable conversation in English. Experts say that with an hour a day for a year, a person should be able to play guitar at an acceptable level. Learning the fundamentals of programming in a basic university course might take about 6 months. The logic is simple, with 200.000 hours you can completely change and personalize your knowledge. And what is also true, is that we are not even remotely close to learning while sleeping.
In a 1997 episode of Friends, “The One with the Hypnosis Tape”, Chandler borrows from Rachel a smoking-cessation audiocassette, to which he listens while he is asleep. The tape tells him that he is “a strong, confident woman” who doesn’t need to smoke. He stops smoking, but also begins acting effeminately. That’s a great example of fiction, but a part recent cinema and television, the idea of learning while sleeping is around since 1927, when Benjamin Saliger invented and traded the Psycho-Phone for sleep learning, stating that “it has been proven that natural sleep is identical with hypnotic sleep and that during natural sleep the unconscious mind is most receptive to suggestions”. The guy sold some thousand units, achieving a good commercial success, with no results for the users obviously.
The idea has been around until 1956, when Charles Simon and William Emmons, researchers at the Rand Corporation, demonstrated that learning while sleeping has no scientific evidence. They attached electrodes to the scalps of participants, monitored them with EEG while asleep and played a tape listing facts and words. Their performance on a memory test upon awakening was no better than chance. The Psycho-Phone and the so called Hypnopedia theory were dead or at least considered not scientific anymore.
In the meantime, technology improved and curiosity about this learning while sleeping stayed. Modern experiments returned mixed results. A great essay written by Kenneth Miller explains us that “in 1996, Japanese researchers put a rudimentary form of sleep-learning to the test by eliciting what psychologists call a conditioned response – linking two stimuli so that repeating the second one triggers a response ordinarily associated with the first. They delivered mild electric shocks to the legs of five sleepers while playing a tone; after awakening, the subjects experienced increased heart rates when they heard the tone alone. The study proved that the sleeping subjects recalled the tone, at least subconsciously.”
The Guardian, in another famous article, reminds us that “in 2010, Susan Diekelmann and colleagues in Germany published a study in which subjects examined specific patterns of objects on a grid before sleeping in the laboratory. While studying, each subject was exposed to a subtle odour in the room, which was later re-introduced when subjects were in a sleep stage called slow-wave sleep. Subjects remembered 84% of the objects’ locations when their memories were paired with the odour during sleep.”
Other examples involved German people learning Dutch (Schreiner & Rasch, Cereb Cortex. 2014 Jun 23. pii: bhu139), a group learning musical tunes (Anthony et al. Nature Neuroscience 2012 Jun 26 15(8):1114-1116) and there are many other scientific experiments about learning while sleeping, cited by popular magazines and websites. But the final conclusion seems always the same: sleep is a time for digesting data, not ingesting it. During sleep, humans strengthen previously acquired memories, but apparently cannot accept new inputs.
In simple words our brain learns in 3 steps: acquisition, consolidation and recall. Acquisition occurs when new information is received, consolidation involves the stabilization of this information in the long term memory and recall is clearly the ability to access and retrieve the information later on, when required. The consolidation happens in a brain region called hippocampus. It takes care of storing new information and moving recent memories to the higher cortical centers where they are consolidated into long term memories. It happens when we sleep. If we don’t sleep, the hippocampus tissues degenerates and we don’t organize memories efficiently.
Researchers went further. According to Dr. Rosenberg, there are three types of memories which are consolidated during sleep and they are declarative (fact-based), emotional (emotion-based) and operational (related to skills learnt by doing). According to a post appeared on the Medical Daily, he says “we believe that declarative memories, such as fact figures and episodic memory occurs during slow wave sleep. Emotional memory processing, which involves the emotional center, the amygdala, and the prefrontal cortex, as well as operational memory… seems to occur during REM sleep”.
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Glimmers of hope in learning while sleeping
This exercise of “segmenting” the sleep and the activities occurring in our brain when we are asleep, led to an interesting discovery. As reported by the same post, “when researchers observed sleeping participants’ brains with EEG scans, they saw theta brain waves being emitted while the snoozers listened to the tape. Theta waves are known to emerge during heightened states of learning, which usually occur during waking hours, suggesting that some level of learning was happening”.
In other words, it seems the official position, that we cannot acquire entirely new information while asleep, can be challenged. There is no technology yet to manage incoming signals, but we assist to potential innovation also on this side. A study published in the journal Frontiers in Human Neuroscience explains that the researchers studied the electric signals in the brain of a trained pilot and then fed the data into novice subjects as they learned to pilot an aeroplane in a realistic flight simulator. Subjects who received brain stimulation via electrode-embedded head caps improved their piloting abilities and learnt the task 33% better than a placebo group. If we are moving in the direction of the brain upload of some abilities, I guess how long it will take to free some of the time used in the consolidation process for the upload. A post from the famous BBC future network, tells us an amazing story: “in the near future, technology may offer further ways of upgrading the brain’s sleep cycles. Memory consolidation is thought to occur during specific, slow, oscillations of electrical activity, so the idea here is to subtly encourage those brain waves without waking the subject. Jan Born, at the University of Tubingen, has been at the forefront of these experiments. In 2004, he found that he could help amplify those signals using transcranial direct current stimulation (tDCS), which passes a small electric current across the skull, successfully improving his subjects’ performance on a verbal memory test.”
It seems that if we are able to get in synch with proper brain’s oscillations during the sleep, we can have some concepts input without waking the person. Once again, it has to be proved with complex items and especially with topics a person has never studied before (i.e. when awake). The consequences of having such a great tool are dual, both positive and negative. Again, the good side of it, would be the possibility to learn many more topics and skills than what we have been to achieve before. The risky side is that your boss asks you to learn and master the presentation or the report for the meeting.
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