Can A Person Learn While Sleeping?

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?

Some Studies Show It Is Possible To Learn New Information During Sleep, Such As New Vocabulary In A Foreign Language.

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Electrical Brain Stimulation:
Walker has developed a device applying precisely timed electrical pulses to enhance slow-wave sleep and memory consolidation during sleep. Challenges remain for home use implementation.

Vibration And Motion:
Research by Sophie Schwartz found gentle rocking motions increased sleep depth by stimulating the vestibular system. Walker sees potential in vibrating mattresses or combining motion with sound.

Acoustic Techniques:
Synchronizing tones to brain waves can enhance sleep, but care must be taken to avoid overstimulation risks. Tailored, adaptive approaches may be ideal.

Meanwhile:

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.

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Sanam Hafeez, a clinical neuropsychologist and professor at Columbia University, explains how this might be possible.

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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.

Updated: 6-21-2019

How Does Your Brain Take Out The Trash?

Let’s Talk About Brainwashing

In this Spotlight, we introduce the glymphatic system: the brain’s dedicated waste clearance system. Now implicated in various conditions, it is high time that we became acquainted.

Astroglia Plays A Pivotal Role In The Brain’s Trash Collection Service

Many of us are relatively familiar with the lymphatic system; it performs a number of roles, one of which is clearing metabolic waste from the gaps between cells, referred to as the interstitial space.

However, the central nervous system (CNS), which comprises the brain and spinal cord, does not have any true lymphatic vessels.

Because the CNS is highly active, metabolic waste can build up quickly.

The CNS is also very sensitive to fluctuations in its environment, so the body needs to remove cellular garbage somehow, and that’s where the glymphatic system comes in.

Before the discovery of this brain-based garbage disposal system, scientists believed that each individual cell handled its own metabolic detritus.

If the cellular system became overloaded or slowed down as we aged, metabolic garbage would build up between the cells. This garbage includes products such as beta-amyloid — the protein associated with Alzheimer’s disease.

Astroglia

The term “glymphaticTrusted Source” was coined by Maiken Nedergaard, a Danish neuroscientist who discoveredTrusted Source the system. The name is a reference to the glial cells, which are vital to this waste clearance system.

Glial cells get relatively little coverage, compared with neurons, despite being just as numerousTrusted Source in the brain. They were long considered little more than lowly support cells, but are now held in higher regard.

Glia protect, nourish, and insulate neurons. They also play a role in the immune system and, as we now know, the glymphatic system.

In particular, a type of glial cell known as astroglia are important. Receptors, called aquaporin-4 channels, on these cells allow cerebrospinal fluid (CSF) to move into the CNS, setting up a current that shunts fluid through the system.

CSF is a clear fluid that surrounds the CNS, providing it with mechanical and immunological protection, among other things.

The glymphatic system, which runs parallel to arteries, also harnesses the pulsing of blood in circulation to help keep things moving.

As the blood vessels expand rhythmically, they drive the exchange of compounds between the interstitial space and the CSF.

The glymphatic system connects with the lymphatic system of the rest of the body at the dura, a thick membrane of connective tissue that covers the CNS.

The Importance of Sleep

Following Nedergaard’s discovery, she ran a series of experiments on mice to develop a better understanding of how this system worked and when it was most active. In particular, the team focused on sleep and Alzheimer’s.

Nedergaard and her team found that the glymphatic system was most busy as the animals slept. They showed that the volume of interstitial space increased by 60%Trusted Source while the mice were sleeping.

This volume increase also boosted the exchange of CSF and interstitial fluid, speeding up the removal of amyloid. They concluded that:

“The restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake [CNS].”

This early work inspired a wave of new studies, the most recent of which was published this month. The researchers looked at the impact of high blood pressure on the function of the glymphatic system.

Over time, high blood pressure causes blood vessels to lose their elasticity, becoming increasingly stiff. Because the regular pulsing of arterial walls drives the glymphatic system, this stiffening impedes its function.

Using a mouse model of hypertension, the scientists demonstrated that high blood pressure-induced artery stiffening did interfere with the way that the garbage disposal system worked; it prevented it from efficiently getting rid of large molecules in the brain, such as beta-amyloid.

This finding might help explain why scientists have found links between elevated blood pressure and cognitive decline and dementia.

Parkinson’s Disease

Parkinson’s disease is another condition characterized by the buildup of protein in the brain. In this case, the protein is alpha-synuclein.

This has led some researchers to wonder whether the glymphatic system might be implicated here, too.

In Parkinson’s disease, there is disruption in the dopamine pathways of the brain. These pathways play an important role in sleep-wake cycles and circadian rhythms; therefore, people with Parkinson’s often experience sleep disturbances.

A review published in Neuroscience & Biobehavioral Reviews proposes that the disrupted sleep patterns could hinder the glymphatic removal of debris, including alpha-synuclein, helping it build up in the brain.

Brain Trauma

Chronic traumatic encephalopathy results from repeated blows to the head; it used to be called “punch-drunk” syndrome because it occurs in boxers.

Symptoms can include memory loss, mood changes, confusion, and cognitive decline.

Some researchers believe that disruptions to the glymphatic system caused by brain trauma may increase the risk of developing chronic traumatic encephalopathy.

The authors of the review write that, following a traumatic brain injury, “Difficulties with sleep onset and maintenance are among the most commonly reported symptoms.”

As we have seen, this interferes with the glymphatic clearance of proteins from the interstitial space during sleep.

At the same time, these types of injury can cause the relocation of aquaporin-4 channels — those important receptors on astroglia that are vital for glymphatic clearance — into a position that hinders the removal of junk proteins from the interstitial space.

The authors believe that the disruption of this system could “provide one link in the explanatory chain connecting repetitive [traumatic brain injury] with later neurodegeneration.”

Diabetes

Beyond a possible role in neurological conditions, some researchers have investigated how disturbances in the glymphatic system may be involved in the cognitive symptoms of diabetes.

Scientists have shown that diabetes can impact a rangeTrusted Source of cognitive functions, both early in the disease’s progression and further down the line.

Some researchers are asking whether the glymphatic system might be involved here, too. A study carried out in mice used MRI scans to visualize the movement of CSF in the hippocampus, a part of the brain involved in forming new memories, among other tasks.

The scientists found that in the mice with type 2 diabetes, clearance of CSF “was slowed by a factor of three.” They also found a correlation between cognitive deficits and impairment of the glymphatic system — if the trash was not getting cleared, thinking skills were hampered.

Aging

As we age, a certain level of cognitive decline is almost inevitable. There is a wide range of factors involved, and some scientists believe that the glymphatic system could play a role.

A study publishedTrusted Source in 2014 investigated the efficiency of mice’s glymphatic systems as they aged; the authors found a “dramatic decline in the efficiency.”

In a reviewTrusted Source of the glymphatic system and its role in disease and aging, the authors write that reduced activity in the system as we age might “contribute to the accumulation of misfolded and hyperphosphorylated proteins,” increasing the risk of neurodegenerative diseases and, perhaps, exacerbating cognitive dysfunction.

We still know comparatively little about the glymphatic system. However, because it cleanses our most sensitive and complex organ, it is likely to influence our overall health to some degree.

The glymphatic system might not contain the answers to all of our questions about neurodegenerative diseases and beyond, but it could hold the key to some interesting new perspectives.

Updated: 4-6-2025

Mary Whiton Calkins

Born: March 30th 1863

Died: February 26th 1930

She was an American philosopher and psychologist, whose work informed theory and research of memory, dreams and the self. In 1903, Calkins was the twelfth in a listing of fifty psychologists with the most merit, chosen by her peers. Calkins was refused a Ph.D. by Harvard University because of her gender.

Calkins is a key figure in the history of women psychologists. At Wellesley College, Calkins established the first psychological laboratory for women. She was the first woman to complete the requirements for a doctoral degree in psychology with the unanimous support of the Harvard University psychology faculty, although the university refused to bestow it on the grounds that Harvard did not accept women.

She later became president of the American Psychological Association and the American Philosophical Association, and was the first woman to be president of both.

She taught psychology and philosophy at Wellesley College for four decades, and conducted research there and at Harvard University for the majority of that time.

To date, attempts to have Harvard award Calkins with a Ph.D. remain ongoing in spite of her passing in 1930. In recent years, women are fighting for Calkins right to such prestigious academic recognition, among them psychologist Kathryn Boatwright who, along with the help of her students, not only wrote a yet another petition to Harvard University, but also created a website to raise awareness to this issue in 2002.

Sleep Stage Definitions:

NREM or Non-rapid eye movement sleep is a type of sleep that includes three stages, characterized by little to no eye movement and varying levels of brain activity. It plays a crucial role in physical recovery, memory consolidation, and overall health.

REM Sleep, or rapid eye movement sleep, is a stage of sleep characterized by rapid eye movements, increased brain activity, and vivid dreaming. It plays a crucial role in memory consolidation, emotional processing, and overall brain health.

Core Sleep refers to the essential stages of sleep that are crucial for physical recovery and mental well-being, primarily including light sleep and deep sleep. It plays a vital role in processes like tissue repair, memory consolidation, and immune function.

Deep Sleep, also known as slow-wave sleep, is a crucial stage of the sleep cycle that helps the brain and body recover and regenerate. It is characterized by slow brain waves and is essential for memory consolidation, growth, and overall health.

Updated: 6-7-2024

The NEXTUP Model: A Science-based Perspective On Dreaming

Dreams have long been shrouded in mystery and associated with the supernatural, often seen as omens, messages from the gods, or glimpses into otherworldly realms. Throughout history, various cultures have attributed profound significance to dreams, interpreting them as divine guidance or as a means of communication with the spiritual world.

However, despite these rich cultural interpretations, it is crucial to approach dreams from a scientific perspective to unravel their true nature and function. Understanding dreams through a scientific lens not only demystifies them but also enhances our comprehension of the human mind, offering valuable insights into the intricate workings of our cognitive and emotional processes.

When Brains Dream: Exploring the Science and Mystery of Sleep by Antonio Zadra and Robert Stickgold offers a profound exploration into the enigmatic realm of dreaming, backed by rigorous scientific inquiry and innovative theoretical models.

The authors, both leading experts in the field of sleep research, unravel the complexities of why we dream and what our dreams signify.

The book delves deeply into the nature of dreams, emphasising their vital role in our cognitive and emotional lives. Zadra and Stickgold meticulously explain how dreams are not merely random occurrences but essential processes that help us navigate and adapt to the complexities of life.

Central to the book is the NEXTUP model, which stands for “Network Exploration to Understand Possibilities.” This model is a sophisticated framework that posits dreaming as a fundamental cognitive process where the brain explores vast networks of stored memories to generate new possibilities.

This model provides a comprehensive framework for understanding the purpose and mechanics of dreaming. Here is a summary of the key elements of the NEXTUP model along with the research methods used:

Element 1: Exploration of Memory Networks: The model posits that dreaming is a process wherein the brain explores vast networks of stored memories. During this exploration, the brain searches for associations and connections among these memories that are not immediately apparent during wakefulness.

Research Methods And Evidence:

Sleep Studies And Experiments: By utilising electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), researchers observed brain activity during REM sleep. These studies showed that memory-related areas like the hippocampus are highly active during dreaming.

Dream Reports And Analysis: Participants’ dream reports were analysed, revealing how dreams often incorporate elements from both recent experiences and long-term memories, supporting the idea of memory network exploration.

Element 2: Possibility Generation: Dreams create new possibilities by combining disparate pieces of information, fostering creativity and problem-solving, and often leading to innovative ideas and insights.

Research Methods And Evidence:

Memory And Learning Experiments: Experiments demonstrated that sleep, particularly REM sleep, improves problem-solving and creative thinking. Participants often showed enhanced performance on tasks requiring creative solutions after a night of dreaming.

Neuroimaging Techniques: Brain scans indicated that regions involved in creative thinking are active during REM sleep, supporting the model’s emphasis on possibility generation.

Element 3: Emotional Processing and Integration: Dreams help process and integrate emotional experiences, aiding in emotional regulation and resilience by replaying and reinterpreting these experiences within a broader context.

Research Methods And Evidence:

Dream Reports And Analysis: Analysis of dream content often shows a strong emotional component, with many dreams reflecting concerns and emotional issues from waking life.

Comparative Studies: Studies of individuals with disrupted REM sleep (e.g., due to sleep disorders) show difficulties in emotional regulation, underscoring the role of dreaming in emotional processing.

Element 4: Threat Simulation And Rehearsal: Dreaming provides a safe space for simulating and rehearsing responses to potential threats, preparing individuals for real-life challenges.

Research Methods And Evidence:

Dream Content Analysis: Many dreams involve threatening or challenging scenarios, which supports the idea that dreams function as a rehearsal for dealing with threats.

Comparative Studies: Research on populations with frequent nightmares (often related to PTSD) highlights how dreams can reflect and rehearse responses to waking life threats.

Element 5: Memory Consolidation And Reorganisation: Dreams play a crucial role in consolidating and reorganising memories, selectively reactivating recent experiences and integrating them with existing memories to strengthen important information while discarding less relevant details.

Research Methods And Evidence:

Memory And Learning Experiments: Participants show improved memory recall and performance on tasks learned before sleep, particularly after REM sleep, indicating that dreaming aids in memory consolidation.

Neuroimaging Techniques: Imaging studies reveal that regions involved in memory processing are highly active during REM sleep, supporting the role of dreams in reorganising memories.

Element 6: Narrative Construction: The fragmented and bizarre nature of dreams results from the brain’s attempt to weave diverse pieces of information into coherent narratives.

Research Methods And Evidence:

Dream Reports And Analysis: Detailed analysis of dream narratives shows that, despite their often bizarre content, dreams strive to create coherent stories, reflecting the brain’s effort to make sense of diverse information.

Element 7: Adaptive Function: Dreaming enhances cognitive flexibility and problem-solving abilities, enabling better adaptation to changing environments.

Research Methods And Evidence:

Problem-Solving And Creativity Studies: Studies demonstrate that individuals who dream about complex problems or tasks often show improved ability to solve these problems, highlighting the adaptive function of dreams.

Element 8: Neurobiological Mechanisms: The model is grounded in neurobiological processes, highlighting specific brain activity patterns during REM sleep, with active memory and emotion-related regions and less active logical thinking regions, facilitating memory exploration and emotional processing.

Research Methods And Evidence:

Neuroimaging Techniques: Advanced imaging studies confirm the unique patterns of brain activity during REM sleep, supporting the neurobiological basis of the NEXTUP model.

When Brains Dream is an insightful and scientifically grounded book that offers a new understanding of the purpose and mechanisms of dreaming. Unlike previous theories, such as Freud’s psychoanalytic model which emphasises unconscious desires, or Hobson and McCarley’s Activation-Synthesis model that views dreams as random byproducts of brain activity, the NEXTUP model highlights the purposeful and adaptive functions of dreams.

This book is essential reading for anyone fascinated by the science of sleep and dreams.

It not only offers a compelling new model for understanding the purpose of dreaming but also situates this model within the broader context of dream research, contrasting and building upon earlier theories to offer a richer, more integrated understanding of this vital aspect of human cognition.

Written By Rohan Roberts

Rohan Is The Director Of The Dubai Science Festival. He Is The Founder Of Intelligent Optimism And Café Scientifique Dubai.

He is currently the Director of Innovation and Future Learning at GEMS Education (world’s largest private education provider).

Can A Person Learn While Sleeping?

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