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

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

Dreams have long been used for religious and political power.

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.

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

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

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

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.

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

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 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.

Near-death experiences have been reported across cultures for millennia.

Humans have speculated about alien life since ancient times

Around 50 B.C.E., Roman poet and philosopher Lucretius shared the idea that alien life was possible, which was put forth by Greek philosopher Epicurus. The writing is believed to be the first straightforward assertion in Western literature that aliens must exist.

Dreaming under the Nazi Regime

Days after Hitler seized power, a man told psychoanalyst Charlotte Beradt that he had dreamed of being forced to raise his arm in a Nazi salute ("It took me half an hour to get my arm up, inch by inch"). Beradt recorded this dream and many others so they "might one day serve as evidence." This is an English translation of her work, "The Third Reich of Dreams."

Philosophers have debated the nature of time since at least the 6th century B.C.E.

Greek philosopher Parmenides of Elea was skeptical of time and reasoned that if it were real, then the present would emerge from nothing because the future did not yet exist. Just as the color red is our perception of a specific wavelength of light, others have suggested time is a psychological projection based on how we interpret the world.

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.

The earliest mention of time travel

Time travel has fascinated humans for centuries. It appears in myths, literature, and science fiction. One of the earliest examples comes from the 400 BCE Hindu epic Mahabharata, describing time dilation long before Einstein’s Theory of Relativity. By the 19th century, stories introduced machines enabling time travel—setting the stage for modern sci-fi.

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

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

Salvador Dalí idolized Freud but was disappointed after they met

Sigmund Freud's writings on dreams and the unconscious profoundly influenced Dalí and his work, and the artist came to idolize the Austrian psychoanalyst. When they met, Freud viewed Dalí as an odd curiosity, and the artist came away disappointed, significantly lowering his opinion of the psychoanalyst.

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 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.

Wilhelm Wundt's place in the history of psychology

While ancient philosophers considered the central problems of psychology, it was Wilhelm Wundt who first called himself one. Here's a quick video overview of his contribution.

Apophenia, 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.

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.

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

Scholars trace existential anxiety back to early Hebrew scriptures

Paul Megna, a scholar of literature and philosophy, notes that the existentialist ideas of Kierkegaard (and, to a lesser extent, Sarte and Camus) had their roots in much earlier texts, which posited that "fear of the Lord" was "the beginning of wisdom."

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

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

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.

Ancient Greece originated roughly 4,000 years ago around the Aegean Sea, and over centuries expanded as far as Spain and India.

The ancient Greeks and Romans viewed comets and meteors as divine omens

Both considered the appearance of a comet or its fragments as a precursor to significant events, such as the birth of a notable figure or the death of a ruler. One observed in 44 BCE was believed to be a sign of the deification of Julius Caesar after his assassination.

An analysis of ancient texts found that dementia was rare in ancient Greece.

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.

Wilhelm Wundt, the forgotten father of modern psychology

He was the first psychologist to call himself one, and he influenced a whole generation of early psychologists. Learn about the life and works of Wilhelm Wundt with this thorough entry from a philosophy encyclopedia.

Wealthy Egyptians slept on woven beds to allow air circulation in hot climates

The history of beds is a fascinating look at economics, social science, and cultural beliefs around what takes place during sleep. This brief survey of the history of bed-making begins roughly 5,000 years ago and runs through ancient Egypt and Rome to modern Europe. Take a look here.

Surrealism toyed with ideas from psychoanalysis

The movement's artists were interested in the ideas being explored in the burgeoning fields of psychology and psychoanalysis. Dalí, in particular, often created works that toyed with Freudian theories.

The scientific name for northern lights came from two Greco-Roman gods

Although cave paintings may have depicted them millennia earlier, one of the oldest known references to auroras is a Babylonian cuneiform tablet from about 600 BCE. In 1619, Galileo Galilei named the phenomenon in the northern hemisphere "aurora borealis" after the Roman goddess of dawn—Aurora—and the Greek god of the north wind—Boreas.

How seizures (potentially) alter consciousness

Seizures occur when intense electrical activity floods the brain, prompting significant loss of self-control and a variety of sensory disruptions and hallucinations. Cultures interpret the episodes differently, with many contemporary norms viewing them as negative while others characterize them as intense spiritual occasions. Author Fyodor Dostoyevsky viewed his seizures this way, as well as cultures in Mongolia, some Shamanic indigenous religions, and others.

One researcher posed a theory that aliens played a significant role in human evolution

Researcher Zecharia Sitchin proposed that Sumerian cuneiform tablets revealed that Sumerian gods were aliens who landed on Earth in Mesopotamia and influenced the creation of modern humans. While his ideas gained cultural interest, they are widely rejected by mainstream scholars.

Before alarm clocks, people relied more heavily on their circadian rhythms, humans hired to wake them, and on tools such as candle clocks that dropped pins in metal trays at roughly set intervals.

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.

The connection between druids and Stonehenge is a historical misconception.

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

The 'definitive' history of magic mushrooms

Where did magic mushrooms come from, and how did they get their magical reputation? This article explains the history of the psychedelic fungi from pre-history to now. The earliest concrete evidence of psychedelic mushroom use is 12,000-year-old murals in Northern Australia that portray mushroom iconography. Considering how many species seek out and consume psychoactive substances, such as Siberian reindeer, it's possible human use of these psychedelic mushrooms may predate these murals.

The prophetic Oracle of Delphi was believed to have a direct line to the Greek god Apollo.

The history of ghosts, explained

The afterlife has perplexed humans across different periods, cultures, and belief systems. The desire to understand what comes next is often explored through the telling of ghost stories. Learn more about the spooky phenomena here.

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

Ancient ghost stories appeared in texts like 'The Odyssey'

Sharing ghost tales has been around for centuries. Ancient Mesopotamia, Rome, and Greece each had their own chilling stories about encountering spirits. Find mentions of specters in some of history’s most famous writings like the "Epic of Gilgamesh" and "The Odyssey."

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.

The origins of our fascination with time travel

Humans have been captivated by the prospect of leaping forward and backward in time for thousands of years. Georgia Institute of Technology Science Fiction Studies Professor Lisa Yaszek recounts how the concept has been utilized by storytellers from 400 BCE to modern-day to explore our relationship with the supernatural, technology, and the past. In a way, this historical recounting is a journey through time.