Can A Person Learn While Sleeping? (#GotBitcoin?)
A growing number of neuroscientists believe that sleep not only helps cement memories, but is actually a time to learn something new. Can A Person Learn While Sleeping?
For most people, the 16 hours spent awake each day are hardly enough time to get critical tasks done, let alone acquire knowledge. Yet a growing number of neuroscientists believe that sleep not only helps cement memories, but is actually a time to learn something new—even a foreign language.
Sanam Hafeez, a clinical neuropsychologist and professor at Columbia University, explains how this might be possible.
Learn This Word: Hypnopedia
Through decades of research, Dr. Hafeez says, scientists have concluded that while we’re bombarded by stimuli all day, sleep is the time when the brain filters all that information. “I think of it as a computer shuffling process: junk, junk, junk, important, junk,” she says. “As it tunes out all these distractions, the brain encodes information and decides how important a memory or a piece of information is.”
A study published in 1965 using electroencephalograms (EEGs) showed that hypnopedia, or sleep-learning, was a real thing. In that and later studies, researchers showed that during certain cycles of sleep that don’t include dreaming, the hippocampus—the primary area of the brain related to memory and learning, as well as in the retrieval of new learning—is activated.
This happens, Dr. Hafeez says, through “neural oscillatory activity,” or the up-and-down of wakefulness that occurs during Stage 2 non-REM sleep, when the heart rate slows and body temperature drops. The “up-down” moments of neural activity, called sleep spindles, last half a second to two seconds and have been shown to play an essential role in sensory processing and long-term consolidation of memory.
“The up spindles of wakefulness help the brain communicate across different areas, transferring data to the correct part of the brain,” she says. Another way to look at it, she says, is the “up” phase is akin to the brain coming up for air for a split second and filing information in the appropriate place for later recall.
‘Guga’ Means ‘Elephant’
In a recent study by researchers at the University of Zurich published in the scientific journal Cerebral Cortex, 68 German students were asked to learn some new Dutch words before 11 p.m. Half the students were allowed to go to sleep while the words were played back to them. The other half stayed awake while listening to the words.
After three hours of sleep or wakefulness, the 68 students were tested on their memory of the new vocabulary at 2 a.m. Researchers found that those who had listened to the words while sleeping retained much more than those who didn’t sleep.
To ensure that the inferior performance of those who stayed awake wasn’t due to sleep deprivation, researchers used EEGs. “The results were clinically significant,” Dr. Hafeez says.
For further evidence that the “up” phase of spindles are the secret to sleep learning, Dr. Hafeez points to another study published in the journal Current Biology by researchers at the University of Bern in Switzerland.
Sleeping participants were exposed to made-up words and their translation while asleep. When the translation was replayed two to four times during the “up” state of a sleep spindle, recall was high, she says. “If they were told that ‘guga’ means ‘elephant’ while sleeping, they were able to remember that ‘guga’ was related to something big when they were awake.”
At least two other studies conditioned subjects to associate smells or sounds with new information while they were asleep. These participants retrieved that new learning when awake, without knowing that they had been exposed to new knowledge as they slept, Dr. Hafeez says.
She notes that people with schizophrenia have few sleep spindles, and women tend to have many more spindles than men, leading many neuropsychologists to infer that brain estrogen production may be important for the consolidation of memory.
Priming Your Spindles
A small industry of YouTube videos has cropped up, aiming to teach new languages that people can listen to while sleeping. Dr. Hafeez isn’t advocating for these sleep-learning language videos, but does believe that good sleep hygiene can help facilitate a higher number of spindles per night. That helps with learning and memory consolidation, both during sleep and while awake.
She recommends cutting back on caffeine by 4 p.m., exercising well before bedtime and using the bed exclusively for sleep. Then, she says, when you listen to that history podcast as you nod off at night, you just might remember a few more details about Henry VIII.
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