The Science Behind Why We Dream

The Science Behind Why We Dream

Dreams have fascinated humans for thousands of years. Ancient civilizations saw dreams as messages from the gods or ways to peek into the future. But what does modern science say about why we dream?

Researchers still don’t fully understand the purpose and mechanics of dreaming.

However, studies in recent decades have shed more light on the science behind our nightly visions. Here’s an overview of some leading theories and discoveries about the causes and functions of dreams.

The Brain During Dream Sleep

To understand dreams, you must first know what’s happening in your brain as you sleep. Scientists identify several distinct sleep stages based on brain wave patterns, eye movements, and muscle tone.

The two main phases are rapid eye movement (REM) sleep and non-REM sleep. Dreams predominantly occur during REM sleep, which first starts about 90 minutes after you fall asleep. Your brain waves during REM look similar to when you’re awake.

During REM sleep, your eyes move quickly, your breathing and heart rate increase, but your body’s muscles are paralyzed, likely to prevent you from acting out dreams.

In contrast, non-REM sleep is divided into three stages characterized by deepening sleep. You spend more time in deep sleep early in the night and more time in REM later on.

REM sleep is critical for many brain functions. Studies show that depriving animals of REM sleep impairs their ability to learn and retain new information. REM sleep is also tied to emotional processing and memory consolidation.

Brain During Dream Sleep

The Activation-Synthesis Theory

One of the first scientific theories of dreaming was the activation-synthesis theory proposed by researchers Hobson and McCarley in 1977. This theory suggests dreams are our brain’s interpretation of random electrical signals during REM sleep.

According to this theory, the brainstem sends random electrical impulses to the forebrain that don’t relay actual sensory information. The cortex then attempts to make sense of these signals by constructing a story-like dream.

Supporters of this theory point to how dreams can seamlessly transition between events and contain things we’d never experience in real life. The activation-synthesis theory proposes our brains synthesize these bizarre dream elements to construct coherent dream plots.

However, this theory doesn’t explain why we dream about certain things or why dreams follow typical themes. Critics argue dreams reflect our experiences, concerns, and emotions rather than just random brain activity.

The Information Processing Theory

Many modern dream theorists believe dreaming helps us process information and emotions.

The information processing theory proposes dreams play a role in memory consolidation and integration. During sleep, your brain replays memories and sorts through information gathered that day. Dreams may be a byproduct of this processing.

Studies show we often dream about autobiographical memories and recent events. People are also more likely to remember new material and solve problems after a good night’s sleep.

REM sleep is believed to be important for turning new memories into long-term ones. Dreaming may strengthen these memories and allow the brain to connect new information with existing knowledge.

girls sleeping in dreaming

The Emotion Regulation Theory

The emotion regulation theory of dreaming focuses more specifically on how dreams help us manage emotions.

This theory suggests dreams allow the brain to process emotional experiences and reduce negative feelings. During REM sleep, your brain is highly active and able to integrate memories with associated emotions properly.

Dreams tend to be dominated by the emotions you felt about an experience, rather than objective details. Strong emotions in dreams may reflect the brain’s efforts to regulate those feelings and prevent emotional distress from building up.

Supporting this theory, studies demonstrate that REM sleep lowers levels of neurotransmitters linked to stress. Dreaming about emotional events could help release pent-up feelings and restore emotional balance.

Why We Dream About Certain Things

Scientists are still seeking to understand why some dreams recur or why certain themes are more common than others. Here are some factors that are known to influence dream content:

  • Daily experiences: We often process events, people, places, and concerns from our waking lives in dreams. Dreams may reflect what’s occupying your thoughts or important activities coming up.
  • Stress and conflicts: Unresolved tensions, fears, and stressful events tend to show up frequently in dreams. Nightmares are often linked to difficulties managing emotions.
  • Recent changes: Dreams commonly work through transitions such as starting a new job or relationship. Major life changes can spark dreaming.
  • Media exposure: Movies, books, songs, and news stories you experience before bed may be incorporated into dream plots. Dreams blend details from reality with fantasy.
  • Physical factors: Dreams can represent physiological needs like hunger, thirst, or a full bladder. Changes in pregnancy and menstrual cycles can also trigger vivid dreams.

While everyone dreams, recalling dreams varies significantly from person to person. Factors like waking up during REM sleep, keeping a dream journal by your bed, and focusing on your dreams improve your chances of remembering them.

conceptual dreams

Common Dream Themes and Their Meanings

Dreams express our inner world in the language of symbols. Here are some insights about why common dream motifs could appear:

  • Flying dreams: Often represent a sense of freedom, overcoming something once holding you back, feeling in control, or having a new perspective.
  • Falling dreams: Could symbolize loss of control, feeling unsupported, or having uncertainty about the future. Falling often relates to anxiety.
  • Being chased: This classic nightmare reflects feeling threatened, avoiding something, or recognizing unhealthy patterns you feel powerless to stop.
  • Teeth falling out: Associated with communication problems, loss of power and control, embarrassment, or significant life changes.
  • Being naked: Dreams about public nudity relate to feelings of vulnerability, exposure, or not being prepared. They often occur during major life transitions.
  • Failing an exam: This popular dream expresses performance anxiety, fears of not measuring up in life, or worry about a lack of knowledge on a topic.

While dream symbols provide clues to interpreting meaning, the most accurate interpretations come from your personal associations. Your dreams reflect your inner world, so you are the best interpreter.

Lucid Dreaming

Lucid dreaming occurs when you realize you’re dreaming within a dream. In a lucid dream, you can control dream events to a certain degree and interact intentionally with the dream world.

Researchers estimate over 50 percent of people have experienced lucid dreams before, often by chance. However, you can learn to lucid dream on purpose with practice.

Lucid dreaming first emerged conceptually in the late 19th century and became a topic of scientific study in the 1980s. To investigate it, sleep scientists look for distinct brain wave patterns, eye movements, and other cues that indicate when a sleeper becomes aware within a dream.

Initial studies suggest lucid dreaming may have psychological benefits and could enhance self-awareness during wakefulness. However, more research is needed to understand its implications.

surreal dreams

Potential Functions of Dreaming

While we don’t fully understand why we dream, researchers believe dreaming likely serves many important functions for our brains and overall well-being. Here are some of the potential benefits and purposes scientists propose for dreams:

  • Memory processing: Dreaming may help strengthen memories and integrate new information into existing knowledge.
  • Emotional regulation: Expressing and regulating emotions in dreams could help prevent negative feelings from escalating or spilling into wake life.
  • Fear extinction: Facing frightening dream scenarios repeatedly may desensitize us to anxiety triggers and reduce future fears.
  • Rehearsal for threats: Dreams allow us to rehearse potential threats and practice dealing with frightening situations that may have survival advantages.
  • Problem-solving: Dreams can link abstract information in creative new ways and may incubate solutions to vexing problems.
  • Creativity: The whimsical, loopy nature of dreams could spark imagination, new perspectives, and creative drive.
  • Threat simulation: Vivid nightmares may function as a threat simulation mechanism, allowing us to experience potential dangers through dreams rather than real life.
  • Virtual stimulation: Some theorists propose dreams provide a form of virtual reality experience that activates brain systems for survival needs like social bonding, aggression, and sex drives.

While dreams may serve all these functions, researchers caution we can’t definitively prove the purposes of dreams yet. More research is needed to uncover the mechanisms and motivations behind our nightly adventures.


Dreams continue to mystify scientists and psychologists. However, ongoing research is lifting the veil on the biology, causes, and possible uses of our nightly dream worlds.

While many questions remain unanswered, science is getting us closer to understanding the secrets of why we dream. Learn here more about dreams and their science.