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

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

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

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.

For most of recorded history dreams were considered divine in origin.

What do your dreams mean, according to science

Humans have been interpreting dreams as signs from deities, spirits, or the psyche for ages, and research shows that reflecting on and analyzing one's dreams can be beneficial. In alignment with dreams' elusive nature, they have no objective or clearly assigned meaning. However, variations of common dreams, such as a surprise exam in a forgotten class, are rife with shared primal fears.

Animal brain studies show brain activity similar to what we'd expect during dreams, but parsing whether animals are truly dreaming depends on how one defines dreaming and how scientists could prove it.

The REM cycle—named for the 'Rapid Eye Movement' that occurs during this stage of intense dreaming—happens around four to six times per night.

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.

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.

We dream for around two hours each night, on average, but the exact purposes of dreams remains under investigation.

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.

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.

Dreams have long been used for religious and political power.

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

The earliest record of dream interpretation dates to Ancient Sumer, an analysis of a Sumerian priest king's dream around 2700 BCE.

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.

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.

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.

Scientists are learning to guide your dreams using sound and touch.

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.

An estimated 1 in 250 people—a small subset of the population—reports they've never remembered a single dream.

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.

Sleep research indicates dogs likely dream about their toys, food, and owners.

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.

Cerebrospinal fluid flushes waste from your brain during sleep, performing a nightly brain cleanup that's an important purpose of sleep.

Famed psychologist Sigmund Freud believed dreams were symbolic expressions of desire.

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.

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.

What happens when we sleep

Sleep is a highly specialized and complex process that begins via signals from a region of the brain called the hypothalamus. As explained in this overview video from The Economist, the hypothalamus maintains our circadian rhythm by using light cues from our environment to regulate sleep via a compound known as melatonin. Once asleep, the brain begins the "sleep cycle" and progresses through the four stages of sleep over and over again each night.

People with a sleep disorder called REM Sleep without Atonia don't experience the temporary paralysis of skeletal muscles that typically occurs during REM sleep—instead, they have vivid dreams that they act out during sleep.

Brain activity sometimes goes into overdrive around the point of death according to researchers' recent analysis of patients' brains before and after they were taken off their ventilators.

There's a new (contested) physiological explanation for near-death experiences based on analysis of the brains of resuscitated coma and cardiac arrest patients.

Emerging research suggests that cannabis, used by about 9% of American adults as a sleep aid, may suppress rapid eye movement and lead to worse quality sleep and fewer remembered dreams.

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.

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

Sleep research published in 2021 confirmed that there is a 'creative sweet spot' when people are drifting off to sleep, and that if they wake up at that point to work, it can boost their creative problem-solving.

The body's response to cardiac arrest has been linked to near-death experiences.

The benefits of lucid dreaming

Lucid dreams happen when the dreamer knows they've stepped out of the bounds of waking life. Studies show it can help dreamers cultivate creativity, process grief, and work through trauma. A 2021 study found that 85% of participants with PTSD no longer qualified for the diagnosis after a week of trauma-informed lucid dreaming in which they intentionally witnessed (and therefore integrated) recurring nightmares or changed the outcome completely.

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.

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

Some scientists argue NDEs are constructed by the brain, not actually experienced

Despite the powerful memories associated with NDEs, scientists question the idea that the experiences prove consciousness endures after death, opting instead to find physiological explanations for common reports of out-of-body experiences, euphoric and lucid thinking, and more.

What happens in a dying brain?

Near-death experiences usually happen during death or on the border of life and death when a person isn't understood to be conscious. This article details the science of what's going on with the brain during NDEs.

Roughly 1 in 5 people experience lucid dreaming at least once a month—that's the ability to control or influence your dream environment.

Scientists are studying dying patients' brain activity in the final moments of life

In the final moments of life there are distinctive bursts of coordinated neural activity. Researchers are interested in parsing that data to better understand the dying process and also exploring how this data relates to our understanding of consciousness.

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.

How do brain scans work?

There's only one thing in our solar system sophisticated enough to study itself: the human brain. But this self-investigation is challenging because a living brain is shielded by skull, swaddled in tissue, and made up of billions of tiny cells. How do we study living brains without harming their owners? Two experts explain how the various techniques like EEGs, fMRIs, and PETs work in this TedEd talk.

The main criticism of a recent neurophysiological explanation for near-death experiences is that these events are too complex to be explained as a neurochemical response to an oxygen-deprived brain.

How science explains déjà vu

Take a fun look at the science explaining the odd experience of déjà vu, which some theories suggest is actually a sign of a healthy brain.

Neural implants blur the line between personal intention and machine execution

A key ethical dilemma—the contemplation conundrum—explores whether implants might misinterpret mere imagination as intent to act. Neuroscientists have found no brain signal that clearly marks when someone decides to act, making intent hard to detect in neurotechnological systems.