Why do we dream? Find out now
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What science and psychoanalysis say about dreams
Dreaming is an experience as common as it is mysterious. We spend about a third of our lives asleep, and during that time, our minds create visual narratives, often bizarre, that can leave us curious, confused, or even frightened. The question “why do we dream?” has intrigued humanity for millennia, from ancient civilizations that saw dreams as prophecies and divine messages. But what do science and psychoanalysis have to say about it? The answer, as we will see, is not singular but involves a fascinating dialogue between the biology of the brain and the complexity of the mind.
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Dreaming: a universal and mysterious experience
Dreams are sensory experiences that occur during sleep, composed mainly of images, sounds, and emotions, but they can involve all senses. They are not an exclusively human phenomenon; mammals and birds also exhibit sleep phases with similar characteristics, suggesting a deep and ancient biological function. Despite being a universal phenomenon, the exact purpose of dreams is still debated, with two major areas of knowledge offering complementary and sometimes divergent explanations: psychoanalysis and neuroscience.
The psychoanalytic view: the royal road to the unconscious
Psychoanalysis, founded by Sigmund Freud in the late 19th century, placed dreams at the center of understanding the human mind. For Freud, dreams were the “royal road” to the unconscious, a privileged access route to the desires, fears, and conflicts that reside outside our consciousness .
Freud and wish fulfillment
Freudian theory posits that the dream is the (disguised) fulfillment of an unconscious wish . During the day, our impulses and desires are censored by consciousness and social norms. When we sleep, this censorship decreases, and these repressed desires try to emerge. However, to avoid disturbing us to the point of waking up, they manifest in a disguised and symbolic form, through what Freud called the dream’s manifest content. The true meaning, or latent content, can only be unraveled through free association, one of the pillars of the psychoanalytic technique .
The dream as a guardian of sleep
Freud also proposed that dreams have the function of protecting sleep. By fulfilling a wish in a hallucinatory way, the dream prevents that impulse from waking us up. If we dream we are drinking water, for example, the brain may be preventing the sensation of thirst from waking us . Psychoanalyst Gustavo Soares adds that the dream also has an elaborative function, helping to process everyday emotional experiences. A nightmare, in this context, can arise when the person “hasn’t properly digested their emotions” .
Jung and psychic compensation
Carl Jung, one of Freud’s main collaborators who later diverged from his ideas, also saw dreams as a communication from the unconscious. However, for Jung, dreams were not just for fulfilling repressed desires. He saw them as an attempt by the unconscious to compensate and balance the psyche, bringing to light neglected aspects of personality or perspectives that consciousness ignores .
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The neuroscience of dreams: what happens in the brain
From the 1950s onwards, with the discovery of REM (Rapid Eye Movement) sleep, sleep science gained new momentum . Neuroscience began to investigate the neural correlates of dreams, seeking to understand their functioning from brain activity.
REM sleep and vivid dreams
REM sleep is the phase in which brain activity resembles wakefulness, eyes move rapidly, and most vivid dreams occur . This phase is crucial for memory consolidation and learning . The discovery of REM sleep was fundamental for dreams to be studied as a biological process, beyond symbolic interpretations.
The Activation-Synthesis Theory
In 1977, researchers J. Allan Hobson and Robert McCarley proposed the Activation-Synthesis Theory, one of the most influential in neuroscience . According to them, dreams are a natural physiological consequence of the brain. During REM sleep, the brainstem sends random electrical signals to the cerebral cortex. The brain, which is constantly trying to make sense of the world, receives this chaotic input and tries to “synthesize” a coherent story from it . In this view, dreams would not have a hidden meaning, being just the “best fit” the brain can make to interpret random neural activation.
Dreams outside REM: the DREAM database discovery
One of the most significant recent advances in the field was the creation of DREAM (Dream EEG and Mentation), the largest database of brain activity recordings during sleep and dream reports. An analysis published in 2025 in the journal Nature Communications, with data from over 2,600 awakenings from 505 participants, confirmed that dreams are not exclusive to REM sleep . They also occur during NREM (Non-Rapid Eye Movement) sleep, the deepest and calmest phase. Surprisingly, when there are dreams in NREM, brain activity more closely resembles wakefulness, as if the brain were “partially awake” . Furthermore, researchers applied artificial intelligence algorithms to analyze brain activity patterns before each awakening and were able to predict, with consistent results, whether the person was dreaming or not .
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Why do we dream? The main biological functions
Although science does not yet have a definitive answer for the function of dreams, some hypotheses are widely accepted and studied.
Memory consolidation and learning
The most widespread hypothesis is that dreams help in memory consolidation . During sleep, especially REM, the brain revisits and processes the day’s experiences, associating them with past memories . Dreaming, therefore, may be a byproduct of this process of organizing and storing information. There is also the theory that dreams are a “slow and gradual learning” that begins in the womb, with the formation of the first sensory representations .
Emotional regulation
Dreams, particularly nightmares, may play a crucial role in processing and regulating difficult emotions . They act as a “private theater” where the mind can explore and elaborate on conflicts, fears, and anxieties in a safe environment . By dreaming, we can relive stressful situations in a way that allows us to “rehearse” emotional responses and find solutions, helping to maintain our self-identity and sense of who we are .
Threat simulation and preparation for real life
Another interesting theory, proposed by researchers like Revonsuo, suggests that dreams function as a “threat simulation” . In this perspective, the brain uses dreams to “train” our response to dangerous situations, preparing us to better deal with threats in real life. This function would have evolutionary value, increasing our chances of survival.
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When dreams can be a warning sign
Most of the time, dreams are a healthy and normal part of our mental life. However, in some cases, they can be a warning sign for more serious conditions. A growing body of neurobiological research suggests that some vivid and recurring nightmares can anticipate illness, signaling physiological changes before the onset of symptoms or detection by conventional diagnostic methods .
The so-called REM Sleep Behavior Disorder (RBD), in which the person physically acts out their dreams, often precedes the motor symptoms of Parkinson’s disease by several years . A 2019 meta-analysis showed that about one-third of patients with RBD developed Parkinson’s or Lewy body dementia after an average of five years . Although these dreams are not a diagnosis, they are a relevant indicator that should be investigated by a healthcare professional.
Conclusion
The question “why do we dream?” does not have a simple answer, but a rich tapestry of explanations that complement each other. Psychoanalysis invites us to see dreams as encrypted messages from our inner world, while neuroscience shows us their biological basis and their importance for memory and learning. The truth likely lies at the intersection of these two views. Dreaming is a complex phenomenon that reveals the deep interconnection between the functioning of our brain and the richness of our emotional life. More than a mystery to be unraveled, dreaming is an essential function that helps us learn, regulate our emotions, and build our own story.
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Frequently Asked Questions
After all, why do we dream?
There is no single answer. Psychoanalysis sees dreams as the disguised fulfillment of unconscious desires and a gateway to the unconscious. Neuroscience understands them as a biological process related to memory consolidation, emotional regulation, and processing daily information.
What is Freud’s theory of dreams?
Freud believed that dreams are the “royal road to the unconscious” and represent the (disguised) fulfillment of repressed desires. Dream content is composed of day residues and manifestations of childhood desires, which appear symbolically to bypass the censorship of the conscious mind .
What is REM sleep and its relationship to dreams?
REM (Rapid Eye Movement) sleep is the phase in which brain activity resembles wakefulness and eyes move rapidly. It is during REM that most vivid dreams occur. This phase is crucial for memory consolidation and learning .
Do dreams have meaning?
For psychoanalysis, yes, and their meaning can be unraveled through analysis. For neuroscience, specifically through the Activation-Synthesis Theory, dreams would be an attempt by the brain to make sense of random neural signals, without intrinsic symbolic meaning . Current science tends to see dreams as a combination of biological and emotional processes.
Why do we have nightmares?
Nightmares can be triggered by stress, anxiety, insomnia, post-traumatic stress disorder (PTSD), or exposure to disturbing content. In psychoanalysis, they are seen as a failure to elaborate conflicts and difficult emotions .
Is it possible to dream outside REM sleep?
Yes. Recent research, including from the DREAM database (2025), confirmed that dreams also occur during NREM (Non-Rapid Eye Movement) sleep, the deepest stage of sleep .
Does dreaming help fix what we learn?
Yes. One of the most accepted functions for sleep and dreams is memory consolidation. During sleep, especially REM, the brain revisits the day’s experiences, associating them with past memories and helping to solidify learning .
What can be considered a warning sign in dreams?
Very vivid and frequent nightmares, or REM Sleep Behavior Disorder (RBD), where the person “acts out” their dreams, can, in some cases, be an early sign of neurodegenerative diseases, such as Parkinson’s, and should be investigated by a doctor .
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