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

Dreams largely occur during REM sleep (but not entirely)

Modern imaging tools have enabled scientists to carry out in-depth studies of brain activity during sleep. Researchers know dreams arise largely during REM, blending emotion-driven visual imagery, memory consolidation, and weak associations to help us make sense of experiences, regulate emotions, and prepare for future situations.

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.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

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.

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.

Studies of psychedelic use may help shed light on the nature of consciousness

The nature of consciousness—what it is, where it comes from, and how it manifests as moment-to-moment experience—remains under debate by scientists. Recent studies show psychedelics were found to boost low-frequency brain signals known as delta waves, a behavior also seen during dream states.

We dream for around two hours each night, on average

Every night we lie down to rest, we spend about two hours traveling through seemingly real experiences as dreams bubble up from our subconscious during various phases of sleep. Despite the ubiquity of the experience, where dreams come from—and what their purpose is—remains largely unanswered.

The neuroscience of REM atonia disorders, where patients act out dreams

What prevents the typical person from acting out their dreams? Temporary paralysis of skeletal muscles, usually leading up to, and during, REM sleep. This academic article and related graphics explore what happens when this process doesn't go as planned, leading to REM sleep behavior disorder.

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.

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.

Gibberish, urine, and utter chaos: what happens when you sleepwalk

Sleepwalking, or somnambulism, occurs most frequently in children who are in the deepest stages of sleep. REM, the sleep stage in which most people dream, often causes temporary muscle paralysis, so it’s only when sleepers pass to the deeper stages of sleep that sleepwalking—and sleep talking—can occur.

Forty to 110 minutes of deep sleep is recommended per night

Adults typically spend 10% to 20% of the night in deep sleep, also known as slow-wave sleep, with the rest of the night spent either in light sleep or REM states.

Neural rhythms shape how we move, focus, remember, and interact with the world

Millions of neurons in the brain produce rhythmic electrical signals, or brain waves, that guide physical movement and help form and store memories. Researchers also use these rhythms to create brain-computer interfaces, letting people control devices using only their thoughts.

The body's sleep-wake cycle is one of its many circadian rhythms

The body's sleep-wake cycle is one of its many circadian rhythms, which are behaviors or biological processes that exhibit 24-hour patterns. These rhythms are deeply impacted by light exposure, food availability, and much more, meaning where you live impacts your sleep.

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.

Poor sleep increases the risk of developing Alzheimer's

Brain imaging studies reveal poor sleep leads to production of amyloid beta proteins—molecules linked to Alzheimer’s—which are cleaned from the brain during high-quality sleep. These findings suggest conditions like sleep apnea and insomnia increase the risk of developing the disease.

Explore a series of bedtime exercises to improve sleep

Low-impact, mindful movements can potentially help the body and mind relax before sleeping. Such exercises could be a helpful complement to regular exercise during the day.

Anesthetics slow brain activity by promoting inhibitory neurotransmitters

Drugs like propofol and isoflurane increase activity at the GABA receptor, which opens chloride channels. These ions enter neurons and hyperpolarize them, making them less likely to fire. Dexmedetomidine instead blocks norepinephrine receptors in the brainstem to sedate patients.

Deep brain stimulation helps manage movement in patients with neurological disorders

DBS is a surgical procedure that uses implanted electrodes to send electrical signals to targeted areas in the brain, interrupting abnormal neural activity. It may be implemented when medications lose effectiveness or cause disruptive side effects.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Olympians view sleep as a performance tool, prioritizing routine and environment

Elite athletes emphasize consistent sleep routines, dark and cool environments, the well-placed nap, and tools like eye masks, white noise machines, and supplements like melatonin (particularly for jet lag). This priority belies a core principle: recovery and performance are inseparable. Read more ways Olympians "sleepmaxx" here.

Watch what depression does to the brain

This video explores the neurobiology of depression and why unraveling the complexities of this disease and its etiology will potentially improve treatments. Effective depression treatment, as this video highlights, can eventually make a depressed brain look like a healthy one on brain scans.

The human brain only uses 5% more energy during active tasks versus resting

Despite only being 2% of the weight of a human body, the average adult brain consumes 20% of its energy, with the majority of it spent on maintaining homeostasis—the stable equilibrium conditions of temperature, acidity, blood sugar, and other properties in the body. For infants, the consumption is closer to 50%.

Ray Dalio credits much of his success to his transcendental meditation practice

Dalio took up transcendental meditation after learning that The Beatles practiced it on a trip to India in 1968. He says the practice allows him to clear his mind, be more creative, and unlock his subconscious.

Brain hemispheres control opposite sides of the body without either dominating

Although distinctions exist between the two halves—language processing is left-oriented, and emotions are right-oriented—signals are sent along neural pathways between the hemispheres and across different regions to collectively process information about external stimuli.

The science behind why some noises have color names

Different noise colors (white, brown, pink, blue) have been proven to affect mood and focus. An audiologist explains that these sounds are named after specific light wave frequencies. While individual preferences vary, certain noises consistently impact sleep, stress reduction, cognitive performance, and problem-solving. The article highlights how these sounds can enhance productivity, relaxation, and even gaming experiences.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

1440: Everything you need to know about Alzheimer's

What is Alzheimer's, and is it different from dementia? In short, yes—Alzheimer's is a specific brain disease that falls under the umbrella of dementia. However it is the most prevalent form of the condition, accounting for 60 to 80% of reported dementia cases.

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Salvador Dalí believed he was his own dead brother, who had died nine months before he was born

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Watch how algorithms can be designed to train themselves and self-improve without human input, to the point where the optimized code is too complex for programmers to understand.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

A small portion of The Winstons' 'Amen, Brother,' an obscure '60s gospel record, is the basis for thousands of hip-hop tracks, making it one of the most sampled records ever that's informally known as 'the Amen break.'

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

44% of Americans say they pray at least once a day—discover how your state's religiosity stacks up against the rest of the country.

After the Boston Tea Party, colonists switched to coffee, which became the main morning drink for revolutionaries.

Walt Disney's early film 'Alice's Wonderland' was a groundbreaking innovation in the silent film era

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO