Dreams: Causes, Types, Meaning, What They Are, And More

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Medical News TodaySubscribeWhat does it mean when we dream?

Medically reviewed by Thomas Johnson, PA-C — Written by Hannah Nichols — Updated on May 16, 2025

Causes
What are dreams?
Interpretations
Dream themes
Brain activity and dream types
FAQ
Summary

Dreams are stories and images that our minds create while we sleep. Dreaming may have benefits, such as helping the brain process information gathered during the day.

Dreams may reflect the cognitive functioning of the brain, which processes memories, conscious and unconscious thoughts, and our experiences in the world.

Fast facts on dreams

We may not remember dreaming, but everyone is thought to dream between 3 and 6 times per night
It is thought that each dream lasts between 5 to 20 minutes.
Around 95 percent of dreams are forgotten by the time a person gets out of bed.
Dreaming can help you learn and develop long-term memories.
Blind people dream more with other sensory components compared with sighted people.

Causes

Person lying on a bed — Guido Mieth/Getty Images

There are several theories about why we dream.

Possible explanations include:

representing unconscious desires and wishes
interpreting random signals from the brain and body during sleep
consolidating and processing information gathered during the day
working as a form of psychotherapy

From evidence and new research methodologies, researchers have speculated that dreaming serves the following functions:

offline memory reprocessing, in which the brain consolidates learning and memory tasks and supports and records waking consciousness
preparing for possible future threats
cognitive simulation of real-life experiences, as dreaming is a subsystem of the waking default network, the part of the mind active during daydreaming
helping develop cognitive capabilities
reflecting unconscious mental function in a psychoanalytic way
a unique state of consciousness that incorporates experience of the present, processing of the past, and preparation for the future
a psychological space where overwhelming, contradictory, or highly complex notions come together from the dreaming ego, notions that are unsettling while awake, serving a need for psychological balance and equilibrium

Much remains unknown about dreams. They are challenging to study in a laboratory, but technology and new research techniques may help improve our understanding of dreams.

Phases of sleep

There are five phases of sleep in a sleep cycle:

Stage 1: Light sleep, slow eye movement, and reduced muscle activity. This stage forms 5% of total sleep.
Stage 2: Eye movement stops, and brain waves become slower, with occasional bursts of rapid waves called sleep spindles.
Stage 3: Extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves.
Stage 4: The brain produces delta waves almost exclusively. It is difficult to wake someone during stages 3 and 4, which are “deep sleep.” There is no eye movement or muscle activity. People awakened while in deep sleep do not adjust immediately and may feel disoriented for several minutes after waking up.
Stage 5: This stage is rapid eye movement (REM). Breathing becomes more rapid, irregular, and shallow, eyes jerk rapidly in various directions, and limb muscles are temporarily paralyzed. Heart rate increases, blood pressure rises, and males may develop penile erections. When people awaken during REM sleep, they can describe bizarre and illogical tales. These are dreams.

Neuroscience offers explanations linking the rapid eye movement (REM) phase of sleep as a likely candidate for the cause of dreaming.

Resources for healthy sleep

To discover more evidence-based information and resources on the science of healthy sleep, visit our dedicated hub.

What are dreams?

Dreams are a universal human experience. They are a state of consciousness characterized by sensory, cognitive, and emotional occurrences during sleep.

The dreamer has reduced control over the content, visual images, and memory activation.

No cognitive state is as extensively studied yet frequently misunderstood as dreaming. There are significant differences between the neuroscientific and psychoanalytic approaches to dream analysis.

Neuroscientists aim to understand the structures involved in dream production, organization, and narration. However, psychoanalysis concentrates on the meaning of dreams and places them in the context of relationships in the dreamer’s history.

Reports of dreams tend to be full of emotional and vivid experiences that contain themes, concerns, dream figures, and objects that correspond closely to waking life.

These elements create a novel “reality” out of seemingly nothing, producing an experience with a lifelike timeframe and connections.

Nightmares

Nightmares are distressing dreams that cause the dreamer to feel several disturbing emotions. Common reactions to a nightmare include fear and anxiety.

They can occur in both adults and children, and causes include:

stress
fear
trauma
emotional difficulties
illness
use of certain medications or drugs

Lucid dreams

Lucid dreaming occurs when the dreamer is aware that they are dreaming and may have some control over their dream.

This measure of control can vary between lucid dreams. Lucid dreams can occur in the middle of regular dreams when the sleeping person suddenly realizes they are dreaming.

Some people experience lucid dreaming at random, while others have reported being able to increase their capacity to control their dreams.

Margaret’s story: Dreams

“My dreams are vivid in color and rich with language and conversation. Dreams are a mix of information processing from the days and moments before sleep and emotions that we are still working through. In a more scientific sense, I believe they serve as a way to help us process our experiences and emotions.

Those recurring dreams — like ones I used to have about missing too many law school classes and not being allowed to sit for the final exam — speak to fears or traumas that our bodies still hold on to.

I also believe dreams are a way for the spiritual world to guide us. Dreams that I remember tend to be ones I know I’m supposed to reflect on and try to figure out what the message is. I’ve even had dreams that led me to a store to buy a very particular moonstone for myself. One of my daughters has prophetic dreams — nothing massively life changing, but things she sees ahead of time. In this sense, dreams help us access the spirit world — and vice versa. A vivid connection to our intuition.”

Interpretations

What goes through our minds just before we fall asleep could affect the content of our dreams.

For example, during exam time, students may dream about course content. People in a relationship may dream of their partner. Web developers may see programming code.

These circumstantial observations suggest that elements from the everyday reemerge in dream-like imagery during the transition from wakefulness to sleep.

Memories

The concept of “repression” dates back to Sigmund Freud, the founder of psychoanalysis. Freud maintained that undesirable memories could become suppressed in the mind. Dreams ease repression by allowing the brain to reinstate these memories.

A 2023 study found a strong link between the content of dreams and the consolidation of newly formed memories, and a 2024 study found that dreams relating to memory may reflect the role of sleep in updating the consolidation of memories and new information gathered throughout the day.

Dream lag

Dream lag is the images, experiences, or people which emerge in dreams being the same as what a person knows in real life.

The idea is that certain types of experiences take a week to become encoded into long-term memory, and some of the images from the consolidation process will appear in a dream.

The dream-lag effect seems to occur in dreams that appear at the REM stage but not those that occur at stage 2.

Memory types and dreaming

Two types of memory can form the basis of a dream.

These are:

autobiographical memories, or long-lasting memories about the self
episodic memories, which are memories about specific episodes or events

A 2024 study exploring different types of memory within dream content among 246 participants found that how individuals remember their past relates to how they experience their dreams, showing that dreaming is a uniquely personal experience.

In 1900, Freud described a category of dreams known as “biographical dreams.” These reflect the historical experience of being an infant without the typical defensive function. Many authors agree that some traumatic dreams perform a function of recovery.

One paper hypothesizes that the central aspect of traumatic dreams is communicating an experience the dreamer has in the dream but does not understand. This can help an individual reconstruct and come to terms with past trauma.

Dream themes

Dream themes can link to the suppression of unwanted thoughts, which increases the occurrence of those suppressed thoughts in dreams.

2023 research indicates the five top subjects or themes of dreams tend to be:

falling
school, teacher, or study
being chased but not being physically injured
enjoying food
repeatedly trying to do an action

Some dream themes appear to change over time. A 2022 study demonstrated that the COVID-19 pandemic in 2020 resulted in a higher rate of pandemic-related nightmares and dreams with distressing content. This could be due to the higher state of emotional anguish.

What do they mean?

Many people hypothesize as to what dreams mean, with some interpretations below:

Relationships: Some have hypothesized that one cluster of typical dreams, including being an object in danger, falling, or being chased, relates to interpersonal conflicts.
Sexual concepts: Another cluster that includes flying, sexual experiences, finding money, and eating delicious food links to libidinal and sexual motivations.
Fear of embarrassment: A third group, containing dreams that involve being nude, failing an examination, arriving too late, losing teeth, and being inappropriately dressed, links to social concerns and a fear of embarrassment.

Brain activity and dream types

In neuroimaging studies of brain activity during REM sleep, scientists found that the distribution of brain activity might link to specific dream features.

Several bizarre features of typical dreams have similarities with well-known neuropsychological syndromes that occur after brain damage, such as delusional misidentifications for faces and places.

Dreams and the senses

A 2024 study found that vision was the most common sensory experience in dreams, followed by audio and touch. By recruiting 533 participants who completed a custom dream diary detailing their dreams, the study found that sensory-rich dreams link to higher emotional intensity.

Interestingly, the study also found that nightmares had more auditory and tactile senses, meaning sound and touch were more common in nightmares than in dreams.

Pain

It has been shown that a person can experience realistic, localized painful sensations in dreams through direct incorporation or from memories of pain.

In one 2023 study, patients with chronic pain seemed to experience pain in their dreams alongside pain in their waking lives.

Death in dreams

A 2023 study states that dreams or nightmares involving death could link to mental health conditions such as:

trauma
anxiety regarding death
anxiety disorders

Death anxiety tends to link to nightmare prevalence, meaning that treating death anxiety could lead to a decrease in nightmares.

Frequently asked questions

How are dreams caused?

Possible theories for the causes of dreams include:

representing unconscious desires
the mind interpreting random signals from the brain and body during sleep
processing and understanding information experienced during the day

What do dreams mean?

Dreams are open to interpretation by the individual. Many dreams may point to underlying desires, wishes, fears, and anxieties.

Summary

Dreaming may benefit a person by helping the brain process information and experiences during the day. Some believe many different types of dreams and themes point to underlying desires or anxieties.

Neurology / Neuroscience
Psychology / Psychiatry
Sleep / Sleep Disorders / Insomnia

How we reviewed this article:

SourcesMedical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Medically reviewed by Thomas Johnson, PA-C — Written by Hannah Nichols — Updated on May 16, 2025

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