People often assume that nighttime dreams are much stranger than the thoughts that drift through our minds during the day. A new study published in Consciousness and Cognition shows that waking mind wandering is just as densely packed with bizarre elements as dreaming, though the nature of the weirdness differs. The findings suggest that both states share a similar foundation of spontaneous offline simulation, challenging old ideas about the strict boundaries between sleep and waking consciousness.
Spontaneous thoughts make up a large portion of our inner mental lives. When our attention drifts away from the task at hand, our minds wander freely through memories, fantasies, and hypothetical scenarios. Nighttime dreaming operates in a largely similar way, unfolding without our direct, deliberate control. Psychologists and neuroscientists have long debated whether dreaming and waking mind wandering exist on a fluid spectrum or represent entirely different categories of experience.
A central point of debate has been the concept of bizarreness. Dream bizarreness refers to the unusual, unlikely, or physically impossible events that happen while we sleep. Common examples include encountering deceased relatives, noticing a familiar room in the wrong city, or suddenly gaining the ability to fly. Some researchers view these strange occurrences as proof that dreaming is fundamentally disconnected from waking life. Others propose that dreaming is essentially just a more intense version of waking mind wandering.
One leading psychological theory suggests that both states are governed by how much cognitive control we exert over our minds. During focused tasks, our thoughts are tightly constrained. During daytime mind wandering, those deliberate constraints loosen, allowing thoughts to drift. In sleep, those constraints are thought to become even weaker, resulting in unguided transitions. If this framework holds true, researchers expected dreams to feature much more discontinuity and bizarreness than daytime thoughts.
To test these ideas, philosophers and consciousness researchers Manuela Kirberg and Jennifer Windt from Monash University in Australia designed a new investigation. Past research often relied on simple questionnaires asking participants to rate the overall strangeness of an experience on a single scale. Kirberg and Windt wanted to look closer at the specific types of unusual elements that populate both states to see exactly how the boundaries of reality bend when the mind goes off script.
The researchers used a method called a self-caught design to capture natural experiences as they happened in daily life. Twenty-one participants recorded one daytime mind wandering episode and one nighttime dream every day for a multi-week period. Participants used a smartphone app to log an audio description of their thoughts or dreams immediately after waking up or noticing their attention had drifted.
This approach yielded 379 distinct audio reports. By having external judges evaluate the transcripts rather than relying on participant self-ratings, the study provided a more objective measure of unusual mental content. The judges broke down each report into individual elements, such as specific people, locations, actions, and objects. They then categorized any oddities into three main types of bizarreness: incongruity, vagueness, and discontinuity.
Incongruity happens when elements are mismatched or simply impossible, such as a dog breathing fire. Vagueness occurs when a location or identity is completely undefined. Discontinuity refers to sudden jumps in time or space, like a person popping out of nowhere. The investigators also measured the density of these unusual traits by calculating the percentage of bizarre elements compared to normal elements within the reports.
When looking at the reports as whole stories, dreams did appear weirder. About half of the dream reports contained numerous strange elements, compared to only a third of the mind wandering reports. This surface-level analysis confirmed the traditional idea that sleep produces wilder thoughts than wakefulness.
Zooming in on the density of the individual elements revealed an entirely different pattern. The researchers found that roughly eight percent of all dream elements were bizarre, compared to nine percent of the elements in mind wandering episodes. Waking mind wandering and nighttime dreaming contained nearly the exact same concentration of strange features. The two states just express that strangeness in different ways.
Beyond the unusual features, the researchers noticed that actions dominated the content of both states. Rather than just seeing passive images, people actively simulated themselves doing things. Additionally, social interactions and other characters made up about a fifth to a quarter of the content in both types of reports, showing that we simulate social worlds whether we are awake or asleep.
In dreams, incongruity and vagueness are incredibly widespread across all categories of thought. Dreamers frequently report contextual mismatches, like finding a childhood bedroom tucked inside a modern office building. Dreams also feature very specific subtypes of bizarreness that never appeared in the daytime mind wandering reports. These unique dream features included fused identities, where a single character possesses the combined physical or personality traits of two completely different people.
Dreams also exclusively featured ongoing transformations. In a sleep state, a friend might slowly morph into a coworker, or a moving train might smoothly shift into a car. These slow, blended mutations give dreams a highly combinatorial narrative structure. The resting brain slowly stitches different memory fragments together to maintain an ongoing, if somewhat illogical, storyline.
Waking mind wandering is highly fragmented by comparison. The researchers found that discontinuity was twice as frequent in daytime thoughts as it was in sleep. When the waking mind wanders, it jumps abruptly from one topic or location to the next. Objects and people do not slowly transform. Instead, they simply vanish and are replaced by completely new, disconnected thoughts. Waking spontaneous thought behaves more like rapidly changing television channels than a blended movie.
The researchers observed that strange elements in daytime thoughts were mostly concentrated around changes to the self. A person might imagine themselves in a different career or looking slightly older. Dreams featured these same alterations but pushed them to impossible extremes. A dreamer might inhabit a completely different body or become a fictional cartoon character in their sleep.
The study provides a highly detailed look into the nature of spontaneous thought, but the methodology does carry certain limitations. The sample size of individual participants was relatively small, even though they submitted hundreds of reports combined. The researchers also noted that participants recorded their experiences at home, meaning there is no brain activity data to confirm exactly which sleep stages produced the dreams.
Participants also submitted longer descriptions and higher quantities of nighttime dreams than daytime wandering episodes. Because people typically remember dreams from the late morning hours just before waking up, and those late-stage dreams are known to be especially unusual, the study might have captured a specific subset of highly vivid dream logic.
Recognizing exactly how these two conscious states diverge and overlap will help scientists better understand how the human brain pulls apart and recombines memories to simulate reality. Future studies could explore how an individual’s age might alter the frequency and strangeness of their unguided thoughts. The relationship between age and the qualitative aspects of spontaneous thought is still poorly understood, providing a fertile ground for upcoming research.
Ultimately, the findings show that analyzing mental bizarreness is like turning a kaleidoscope. Depending on the exact angle or scale of measurement, a completely different pattern of similarities and differences emerges. Nighttime dreams cannot simply be dismissed as inherently more bizarre than daytime daydreams. A nuanced approach is required to fully grasp the limits of human imagination.
The study, “The kaleidoscope of bizarreness: The analysis of first-person-reports shows the relationship between dreaming and mind wandering to be complex,” was authored by Manuela Kirberg and Jennifer Windt.