During dream sleep, the brain connects new information learned during the day with information already stored in the mind, creating a revised mind-wide web of associations.

The brain consolidates memories during sleep

During sleep, the brain appears to process memories from the day and encode them into long-term storage. At the same time, the brain prunes old memories out of the brain that are no longer useful. Understanding this process also sheds light a various neurodegenerative diseases.

How dreams affect your memory

In 1999, scientists conducted a study in which participants were asked to recall images flashed before them for milliseconds. They found that participants who slept before recalling the information performed better than those who had been asked to recall the same information that same day. This was some of the earliest convincing evidence of how crucial sleep is for learning and memory, findings that current research continues to strengthen.

Dreams largely occur during REM sleep (but not entirely).

The dreaming brain, as understood by scientists

Technology has advanced to where the seemingly separate fields of psychology and neuroscience are asking the same questions about dreams, such as whether they're more closely related to perception or visualization. Some field-intersecting findings include research that shows people with impaired face perception don't dream of faces, those with brain legion-related cognition difficulties deal with similar issues in dreams, and children's dreams change in parallel to their cognitive development.

Sleep is no longer considered a binary state—scientists are seeking to map a variety of liminal states between sleep and waking, including the hypnagogic state associated with boosts of creativity.

Dream interpretation has evolved from ancient mystical explanations, to dream reports, to tracking electrical activity in the brain and more.

Your brain moves through four distinct sleep stages every night

Each stage plays a key role in memory, repair, restoration, and other key biological functions. The full cycle generally proceeds from light sleep and deep rest into vivid REM dreaming, which repeats between three and five times nightly.

The study of dreams, formally called oneirology, has evolved over the centuries, from anecdotal interpretations to advanced brain imaging.

Cerebrospinal fluid flushes waste from your brain during sleep

Recent research suggests a nightly brain cleanup as an important purpose of sleep. Brain waves have been observed to work in lockstep with the brain’s blood flow and cerebrospinal fluid flow, allowing for a cleansing tide that washes away toxic waste.

Why don’t you remember all your dreams?

Despite being a near-nightly occurrence, we remember very few of our dreams. Researchers believe reduced activity in regions where memories are stored, a different neurochemical environment during sleep, and rapid transition during waking contribute to this phenomenon.

The hippocampus, located deep inside the temporal lobe, appears to play a central role in dreaming and memory, according to recent research on dreaming and damage to that area of the brain.

Sharp wave ripples in the brain tag experiences for long-term memory storage

These ripples were known to quickly replay neuronal sequences during sleep for consolidation. While awake, they help the brain prioritize memories to remember, and their disruption can impair memory formation.

Sleeping on a problem does seem to help—in fact research published in 2026 suggests scientists can seed people's dreams with sound cues about a difficult puzzle during REM sleep and they'll be better able to solve it.

Consistency and emotional engagement can improve the formation of memories

While sleep lets the brain re-trigger neurons associated with our experiences to cement them in long-term memory, repeating actions, like storing one's keys in the same location, can mimic these benefits. Emotionally charged memories are often ruminated upon, improving their future recall.

Several brain regions are involved in lucid dreaming, a state in which a person knows they're dreaming.

Why do dreamers twitch?

This thought-provoking piece highlights newer research suggesting sleep twitches may not be random dream leftovers, but instead a crucial way our brains map and understand our bodies. From sleeping rat pups to dreaming octopi, this biological mapping system appears universal across animal species.

How your subconscious influences your decisions

How much of your desires and daily choices are truly yours? One of the most effective ways to influence someone's subconscious is when they're asleep. To study this possibility, researchers trained participants to be able to dream lucidly, a phenomenon that occurs when a dreamer knows they're dreaming.

Delta brain waves happen during deep sleep, while REM cycles resemble being awake

As the brain cycles from wakeful rest to deep sleep, different brain waves emerge. Alpha waves occur during restful waking states, while theta waves can be associated with light sleep and meditation. Delta waves are observed during deep sleep—but REM cycles more closely resemble active awake states.

What is the brain up to when the mind wanders?

As you stare into the distance while washing your home's seemingly never-ending pile of dishes, the brain activates its default mode network. This collection of "task-negative" brain regions associated with memory, reward, action consideration, and prediction alight with activity when humans mentally turn inward, possibly giving rise to the brain's ability to wander and humans' ability to construct internal narratives about the world.

The brain will attempt to rest itself in periods of chronic sleep deprivation

Skimping on sleep lengthens reaction times and blunts decision-making skills. At a certain point, the brain will try to sneak sleep where it can, shifting sections offline even as you remain awake. Going without sleep raises blood pressure, undermines the immune system, and increases one's risk of dementia.

Psychedelics set off a flurry of brain activity that may permanently alter it

The brain seems to experience a sharp increase in communication between areas that generally don't interact. New research suggests a thin, sheet-like gray matter structure tucked deep within the brain, between the insular cortex and striatum, may be the key to this change. The area is centrally located and home to many of the receptors that psychedelics target, potentially rewiring the brain and rewriting thought patterns.

A sleep expert discusses the broad benefits of quality rest

In this three-part series, renowned sleep expert Matthew Walker and doctor Peter Attia explore the role of sleep in memory consolidation and mental health, and the detrimental effects of chronic lack of sleep. The latter has been linked to increased risk of dementia, hypertension, and more.

Visualizing how we dream via Google search trends

When dreams perplex us, we often want to understand them—and in the age of Google, millions go to its search engine to find answers. Now, researchers have compiled a decade's worth of dream-related queries to glean dream trends across seven languages. See what dream was most commonly searched in Arabic in 2015, or what fears and hopes are specific to one culture and time alone with this unique visual essay.

How to remember everything

On average, people can remember seven different things using their working memory. To better retain all the things we need to remember, Tiago Forte developed the Second Brain method: a simple approach for immediately capturing, organizing, and storing the myriad tasks, learnings, and resources we collect throughout the day.

Memory exists as multiple types stored across various brain systems

Memory isn't one uniform function—it's made up of multiple systems, like declarative (facts/events) and non-declarative (skills/habits), which involve different brain areas such as the hippocampus, amygdala, and cerebellum.

'Those who dream by day are cognizant of many things which escape those who dream only by night.'

- Edgar Allan Poe (1809-1849) in "Elenora"

Modern media exposure may impact whether people dream in color or black and white.

Research suggests the brain maintains connections to lost limbs

Decades-old research suggested brain reorganization after amputations, but brain scans show unchanged limb representations. Phantom limb pain may result from such unchanged brain maps, which may enhance prosthetic limb control in brain-computer interface technology.

Mathematicians often solve problems using wordless mental processes

It's a common technique among expert mathematicians, where thinkers rely on intuition, blurry perceptions and subconscious work—no writing, no formulas. The state is distinct from daydreaming, and often relies on sudden illuminations stemming from extended periods of subconscious reflection.

Sleep is often viewed individually, when its impact and meaning may be more communal

At any given point, roughly 2 billion people may be asleep on Earth. The typical scientific description of sleep focuses on its individual impact, but the phenomenon shapes whole cultures and eons. This essay prompts a fresh rethinking of the importance of sleep for humanity.

Dreams have long been used for religious and political power.

Long-term memory formation may not need short-term memory

New research shows that long-term memories can still develop even when short-term memory formation is blocked, suggesting the brain uses separate pathways for short- and long-term memory. This discovery could help scientists open new avenues for treating memory loss in diseases like Alzheimer’s.

Playing music enhances the creation, storage, and retrieval of memories

Scans of the brains of individuals who play instruments have shown enhanced connectivity between multiple brain regions—visual, auditory, and motor cortices—and the corpus callosum, which connects the two brain hemispheres. These complex connections are strengthened through practice and then used in other activities that involve both logic and creativity. The brains of musicians also appear to give experiences multiple types of memory tags, such as audio, emotional, and conceptual, improving their processing.

Déjà vu is a memory illusion involving brain regions correcting inaccurate memories

Neuroscientists suggest the phenomenon is your brain recognizing that this feeling of familiarity is incorrect, showing off the brain's internal fact-checking system. Younger people experience déjà vu more often because their brains have higher excitatory activity and stronger memory monitoring systems.

Pareidolia, the cognitive bias that leads people to find meaning in randomness, helps explain why humans look for meaning in their dreams and even in their tea leaves.

Brain activity goes into overdrive around the point of death

Recent studies suggest increased electrical activity in the brain during and after clinical death could be responsible for near-death experiences. Both high-frequency gamma waves (linked to perception and attention) and low-frequency beta waves (related to focus and concentration) increased and became more synchronized across multiple brain regions, potentially resulting in a near-death state of heightened consciousness.

Synaptic plasticity allows neurons to communicate effectively and form memories

First proposed in 1949, synaptic plasticity allows the brain to adjust communication strength between neurons. This ability to change synaptic strength—either briefly or over long periods—is essential for learning and memory, with long-term synaptic plasticity forming the basis of how memories are stored.

The doorway effect is when people forget their task when entering a new space

The "why did I come in here?" feeling after walking into a room comes from the brain creating event boundaries to organize memories. Mentally revisiting a previous room can help recall tasks and reverse memory loss. (Some readers may experience a paywall.)

Sensory memory is information collected from your senses

Lasting seconds before moving into short-term memory or being forgotten, sensory memory aids in environmental awareness and navigation. Key brain regions involved include auditory, somatosensory, gustatory, visual, and olfactory cortices.

Sleep paralysis occurs when the body fails to 'unfreeze' in sync with waking.

How brain cells carry information

At any moment, there is an electrical storm coursing through your body. Discover how chemical reactions create an electric current that drives our responses to everything from hot pans to a mother’s caress.

Researchers use the brain's ability to edit memories to explore memory deletion

Scientists have successfully implanted false memories in mice after studying how the editing process works in the brain. Beyond potentially deleting memories in those with PTSD, upcoming research may allow clinicians to forecast the onset of neurodegenerative diseases.

What’s with the teen brain, anyway

In this video NIDA explores the intriguing similarities between the processes of brain development and computer programming. This analogy helps us understand why toxic environmental factors like drugs, bullying, or lack of sleep strongly affect a teenager’s life The information provided by this video can empower your children or students with information they need make better decisions.

False memories can form during recall when new information is incorporated

Often formed due to suggestion and misinformation, false memories can lead to serious consequences, such as wrongful convictions. The time between an event and recalling it affects one's susceptibility to false memories.

A pregnant woman's brain sheds gray matter, perhaps explaining 'baby brain'

The brain areas involved in processing information and emotions decrease by an average of almost 5% during pregnancy. Researchers discovered in a 2025 study that this mostly temporary change—the brain hadn't fully returned to its normal size six months after pregnancy—seems to be associated with self-reported improved bonding and less hostility toward the child postpartum.

How the brain processes a calendar year

When most of us picture a calendar year, we have a foggy image in our minds of the months, in rough, calendar-like grids. But for some folks, that picture is a whole lot more clear. Around 1 percent of the population has a strange ability known as "calendar synaesthesia," which means they're able to visualize in crisp detail an elaborate calendar of the months of the year. Learn how it works here.

Explaining the physical connection between the gut and brain

This video overview from Duke University helps visualize the gut-brain axis—a physical connection of nerves running from the brain to digestive tract that acts as a physical and chemical link.

Nightmares are unpredictable, but are linked to stress, anxiety, trauma, and more.

Carl Jung proposed the controversial idea of the 'collective unconscious'—all humans share a common psychic realm.

How alcohol rewires your brain

Alcohol doesn't just make you tipsy—it rewires your brain chemistry in real time. It slows your brain with GABA, spikes dopamine to make you feel unstoppable, and blocks glutamate so you can't form memories. That mix explains everything from slurred speech to blackouts … and brutal hangovers.