Dreams

Dreams and their associated interpretations have varied widely across different cultures and periods of time. Dream interpretation has its roots in the oldest historical records of Mesopotamia, China, Egypt, Greece, and Rome,^[1] and continues to remain a  source of wisdom and insight within many cultures today.

Theories on Dreaming

Theory	Theorist/Researcher	Key Concepts	Notable Ideas
Freudian Theory of Dreaming	Sigmund Freud	Manifest content, latent content	Dreams are a pathway to the unconscious; dreams have hidden meanings linked to desires and conflicts.
Collective Unconscious	Carl Jung	Collective unconscious, archetypes	Dreams tap into shared universal knowledge and symbols common to all humans.
Emotional Regulation Theory	Rosalind Cartwright	Emotional regulation, problem-solving	Dreams help process emotions, linking current feelings to past memories, aiding in mood regulation and problem-solving.
Activation-Synthesis Theory	J. Allan Hobson and Robert McCarley	Random neural activity, synthesis	Dreams are the brain’s attempt to make sense of “random” neural activity during REM sleep; not inherently meaningful.
Threat-Simulation Theory (extended to Social-Simulation Theory)	Antti Revonsuo Revonsuo, Tuominen, & Valli	Evolutionary advantage, threat practice Social rehearsal, bonding, empathy	Dreams act as an evolutionary mechanism for rehearsing responses to threats. Dreams simulate social interactions and strengthen social cognition and emotional skills.
Expectation-Fulfillment Theory	Joe Griffin	Emotional discharge, instinct fulfillment	Dreams serve to deactivate emotional arousals not expressed during the day, likened to “flushing” emotional stress. This is considered controversial and hard to test.
Memory Consolidation Theory	Multiple researchers	Memory processing, long-term memory formation	Dreams play a role in processing and integrating memories, with sleep aiding in the consolidation of new information.
Continual-Activation Theory	Jie Zhang	Memory processing, neural activity	Dreams are a byproduct of the brain’s need to constantly create and consolidate memories, especially when external input is low. This still has limited empirical support.

Dream Theories

Freud’s Dream Analysis Sigmund Freud posited that dreams are a pathway to the unconscious. By analyzing dreams, Freud thought people could increase self-awareness and gain valuable insights to help them deal with the problems they faced in their waking lives. Freud made distinctions between the manifest content and the latent content of dreams:

• Manifest content is the actual content, or storyline, of a dream.
• Latent content, on the other hand, refers to the hidden meaning of a dream.

For example, a dream about being chased might symbolize a deeper concern about an unresolved issue.

Jung’s Universal Symbols Carl Jung expanded the psychological significance of dreams by suggesting they connect us to a collective unconscious—a shared heritage of archetypes and symbols. He believed dreams could reveal universal truths that transcend individual experience.

Contemporary Dream Theories

The exploration of dreams didn’t stop with Freud and Jung. Modern theories offer diverse perspectives:

• Rosalind Cartwright’s Emotional Regulation Theory: Dreams are seen as a cognitive space where emotions are processed and regulated, linking present experiences to past memories, and aiding in coping with stress.

  Cartwright’s theory is supported by evidence from studies that have shown that emotional experiences during waking life can influence dream content. According to this theory, conditions like depression may represent a failure to sufficiently regulate mood at night.

  Unlike Freud and Jung, Cartwright’s ideas about dreaming have found empirical support. For example, people who experience traumatic events are more likely to have nightmares, and people who are going through a period of intense stress may have more vivid and emotionally intense dreams.

  She and her colleagues published a study in which women going through divorce were asked several times over a five-month period to report the degree to which their former spouses were on their minds. These women were awakened during REM sleep in order to provide a detailed account of their dream content. There was a significant, positive correlation between the degree to which women thought about their former spouses during waking hours and the number of times their former spouses appeared as characters in their dreams (Cartwright, Agargun, Kirkby, & Friedman, 2006).

• 

  Activation-Synthesis Theory by Hobson and McCarley: This theory challenges the search for hidden meanings in dreams, suggesting instead that dreams are the brain’s attempt to interpret random neural signals during REM sleep.

  According to this theory, during REM sleep, the part of our brain that controls our thoughts, imagination, and emotions becomes very active. This can cause random signals to be sent to the brain, which may include images, memories, emotions, and sensations. According to this theory, the brain then tries to make sense of these random signals by creating a story or narrative out of them. This process is known as synthesis. The brain combines different signals to create a dream that is like a movie, where we experience a variety of scenes, characters, and events.

  Building on activation-synthesis theory, neuroscientists J. Allan Hobson and Karl Friston have proposed that both waking and dreaming consciousness operate through predictive processing—the brain’s constant effort to predict incoming sensory information and minimize prediction errors. During waking life, the brain uses a hierarchical system where each level generates predictions about what sensory information it will receive, then adjusts these predictions based on actual input.^[2]

  During REM sleep, this same hierarchical system continues operating, but with a crucial difference: sensory input is minimal. The brain must rely almost entirely on its internal, high-level predictions to generate experience. This explains why dreams often lack fine-grained perceptual details compared to waking life—the brain is operating primarily from abstract, top-down predictions rather than detailed sensory data.

  From this perspective, dreams represent the brain continuing its fundamental job of making sense of the world, but doing so in the unique neurochemical environment of sleep where external reality checks are absent. 

• Threat-Simulation Theory: Dreams are considered an evolutionary adaptation, providing a virtual reality where we can rehearse responses to threats.

  The theory suggests that dreaming should be seen as an ancient biological defense mechanism. Dreams are thought to provide an evolutionary advantage because of their capacity to repeatedly simulate potentially threatening events. This process enhances the neurocognitive mechanisms required for efficient threat perception and avoidance by allowing us to practice dealing with potential threats in a low-stakes environment.

  An updated view extends threat-simulation into our social lives in the social-simulation theory: dreams frequently rehearse social interactions, not just dangers. Content analyses show that dreams are rich in social scenarios, consistent with the prediction that dreaming helps maintain or refine social cognition and bonding (Tuominen, Stenberg, Revonsuo, & Valli, 2019). 

• Expectation-Fulfillment Theory: Dreams are thought to serve as a psychological “flush,” deactivating unexpressed emotional arousals from the day.

  According to Joe Griffen, dreams are nature’s evolutionary solution to animals’ need to inhibit arousals, such as anger, the urge to eat, or the urge to mate; whenever such instincts are inappropriate or dangerous to act on at the time, the arousals are safely deactivated later in dreams. This practice frees up space in the brain to deal with the emotional arousals of the next day and allows instinctive urges to stay intact. In effect, the expectation is fulfilled (the action is “completed”).

  This theory also says that excessive worrying arouses the autonomic nervous system, which increases the need to dream during REM sleep. This deprives the individual of the refreshment of the mind and body brought about by regenerative slow-wave sleep.

• Memory Consolidation Theory: This theory posits that dreams facilitate the processing and integration of memories, helping to transfer information from short-term to long-term storage.

  This theory suggests that while we sleep, our brains process and consolidate the memories and experiences of the day, integrating new information with existing knowledge. According to this theory, during sleep, the brain processes and consolidates declarative memories, which are related to the conscious recall of facts and events. This process of consolidation involves the transfer of memories from the hippocampus, where they are initially stored, to other parts of the brain for long-term storage.

  While many theories focus on how dreams process past experiences, recent research suggests dreams may also be forward-looking. Research by Erin Wamsley (2021) found that over half of dreams incorporate memories from multiple past experiences, and approximately 26% of dreams relate to specific upcoming events. Importantly, many future-oriented dreams combine fragments from several past experiences to construct novel scenarios.^[3] This constructive episodic future simulation suggests dreams don’t simply replay memories—they actively recombine past experiences to help us anticipate and prepare for probable future events. While these dreams rarely depict future events realistically, the activation and recombination of future-relevant memory fragments may serve an adaptive function, helping us mentally rehearse various possibilities.

• Jie Zhang’s Continual-Activation Theory: Dreams are a byproduct of the brain’s need to continually process information and maintain neural circuitry, especially during periods of sensory deprivation like sleep.

  This theory also suggests that when external sensory input is low, such as during sleep, the brain may generate its own input in the form of dreams to keep the neural circuits active and engaged.

Lucid dreams are dreams in which certain aspects of wakefulness are maintained during a dream state. In a lucid dream, a person becomes aware of the fact that they are dreaming, and as such, they can acquire the ability to control the dream’s content (LaBerge, 1990).

Recent research (Horikawa, Tamaki, Miyawaki, & Kamitani, 2013) has uncovered new techniques by which researchers may effectively detect and classify the visual images that occur during dreaming by using fMRI for the neural measurement of brain activity patterns, paving the way for additional research in this area. Artificial intelligence may even be used to recreate the visual components of dream content using fMRI scans of sleeping participants.^[4]

Research has lent support to some of these theories, particularly those emphasizing the role of dreams in emotional regulation and memory consolidation, but this field is ever-evolving due to the difficult work of analyzing dreams and rapidly evolving technological advancements. Do any of these theories seem to best fit with your own dream experience?

Research Highlight: Enhancing Memory During Sleep

Can you strengthen memories while you sleep? Recent research suggests it’s possible through a technique called Targeted Memory Reactivation (TMR).

How It Works

Your brain naturally replays and strengthens memories during sleep—a process called memory consolidation. TMR takes advantage of this by creating associations between learning material and sensory cues like sounds or scents. When these same cues are presented again during sleep, they prompt the brain to reactivate and strengthen those specific memories (Carbone & Diekelmann, 2024).

For example, students might study vocabulary while an incense stick burns nearby, then place the same incense by their bed while sleeping. The familiar scent triggers memory reactivation during the night, leading to better recall the next day.

What the Research Shows

Studies have demonstrated TMR’s effectiveness across different types of learning. Students who studied English vocabulary or history lessons with a specific scent present, then were exposed to that same scent during sleep, showed significantly improved test performance compared to control groups (Neumann et al., 2020; Vidal et al., 2022). The technique has successfully moved beyond laboratory settings into actual classrooms, where 6th graders achieved substantial memory improvements using this approach at home.

Interestingly, timing matters. Memory cues delivered during specific phases of deep sleep—particularly during slow-wave sleep “up-states”—produce stronger memory benefits than cues delivered at other times (Ngo & Staresina, 2022). Different sleep stages also appear to support different types of memory: slow-wave sleep is particularly important for factual information, while REM sleep may be especially important for emotional memories and physical skills.

While promising, TMR doesn’t work universally—effectiveness varies depending on factors like sound intensity, sleep quality, and individual differences. The technique works best when sleep isn’t disrupted, as sounds that are too loud can actually impair memory rather than help it. Researchers are now exploring whether TMR might have clinical applications, such as reducing nightmares or helping update unwanted emotional memories, though much more research is needed.^[5]

 

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