Experiments exploring the effects of missing a night’s sleep on the human brain have found indications that a sleepless night actually increases connections between brain cells instead of impeding growth. However, the lack of sleep could also create brain “fatigue” and pressure, resulting in burnout.

The Forschungszentrum Jülich Institute of Neuroscience and Medicine team behind the discovery said that their findings might support the idea that sleep plays an important role in restoring the brain’s cellular balance.

Missing a Night’s Sleep Could Disrupt Cellular Balance

In a statement announcing the surprising discovery, study leader David Elmenhorst and colleagues note that scientists still are not in complete consensus about why humans and other animals need sleep. One proposal involves restoring synaptic connections between brain cells during certain stages of sleep, helping the brain maintain a form of cellular ‘homeostasis.’

For example, previous research has shown that synaptic connectivity increases during wakefulness. This increased activity also increases energy consumption, potentially resulting in problematic protein buildup. Conversely, scientists suspect that sleep helps restore baseline synaptic connections and protein levels, thereby maintaining a healthy cellular balance.

“Sleep is essential for synaptic homeostasis, a proposed mechanism whereby wake­fulness leads to synaptic potentiation, and sleep facilitates synaptic down-selection,” the research team explains in a recently published study.

Although previous studies suggest that missing a night’s sleep could disrupt this balance, the team notes that there is very little experimental data to support these conclusions.

Study Reveals Elevated Synaptic Activity After 28 Hours Awake

To explore the role of sleep in cellular homeostasis in the human brain, the researchers used an advanced brain-scanning technology called positron emission tomography (PET). According to the team’s statement, this tool can scan the human brain for signs of synaptic vesicle glycoprotein 2A (SV2A),  which they describe as a “marker” of brain synapses.

The team started by enlisting 40 study volunteers. Next, each volunteer was given a PET scan to establish baseline marker levels. After their first scan, 20 of the volunteers were told to get a normal night’s sleep. According to the study authors, the second half were assigned to “the sleep deprivation condition,” where they were told to miss a night’s sleep.

The next day, the team used the PET scan to search for telltale brain synapse markers. As hoped, the scans revealed a distinct difference between the two groups. Where the normal sleep group’s levels were within expected ranges, the synapse markers of the volunteers who had missed a night’s sleep were elevated.

A closer analysis found that once people passed 28 hours of continued wakefulness, their SV2A markers were higher “in several brain regions.” Notably, these increased markers were detected in the hippocampus, which plays an important role in memory, and in the thalamus, which is critical for information relay within the brain.

“Sleep deprivation led to significant increases in synaptic vesicle glycoprotein 2A binding in multiple brain regions, including the thalamus (+4.6%), hippocampus (+5.6%), and parietal cortex (+3.2%), whereas no changes were observed in controls,” the study authors write.

Sleep Deprivation Causes Fatigue and CHanges Neural COnnections

When discussing the study’s limitations, the authors note that the SV2A marker used is a “proxy” for connections between brain cells, not a direct measure. They also note that the observed changes after a missed night’s sleep “were relatively small.” Still, they add, the results in several regions across several study participants “suggest a biological connection between the need for sleep and the buildup of cell connections.”

“During sleep deprivation, the brain remains awake longer and continues to process stimuli and information,” they write. “Our study shows that after approximately 28.5 hours of wakefulness, a marker for synaptic density increases in several brain regions. This suggests that sleep deprivation not only causes fatigue but is also accompanied by measurable changes in neural connections.”

The study “Sleep deprivation increases levels of the synaptic density marker SV2A in the human brain” was published in PLOS Biology.

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.

A hummingbird, a beetle, and a human may inhabit the same moment, but according to new research, each species experiences that moment unfolding in a fundamentally different way.

While scientists have traditionally measured animal time perception using simple metrics like flicker detection, a new study argues that such approaches capture only a fraction of how creatures experience reality. Instead, the researchers propose that every species inhabits its own unique “timescape,” shaped by biological processes that govern how sensory information is assembled, updated, remembered, and interpreted.

Understanding these distinct temporal worlds, they say, could provide new insights into animal behavior, consciousness, and the evolution of perception itself.

Quantifying the Experience of Time

Jakob von Uexküll, an early 20th-century German zoologist, developed the idea that different animals experience reality in their own unique bubble, dictated by their biology’s unique combination of sensory inputs and processing. From the German word for “environment” or “surroundings,” he called the unique sensory experience of each animal an “Umwelt.”

In previous work, the critical flicker fusion threshold (CFFT), which measures the Hz at which a creature perceives a flickering light as steady and continuous, was used as the sole metric to quantify how animals perceive visual content over time, but the researchers say this is far too shallow a standard.

CFFTs occur in a broad range of frequencies between 4 and 500 Hz, which the researchers say could give a false impression of the rate at which experiences flow for other creatures. The authors note that “Even in humans, CFFTs are uninformative about the temporal regularities over which our perceptual mechanisms anticipate, organize, revise, or attend to perceptual inputs.”

The issue, they say, is that CFFTs only measure retinal sensitivity, not how a creature cognitively experiences timescales. This can lead to the false assumption that certain animals perceive time more rapidly than others, but that may be incorrect without accounting for the full cognitive picture.

A More Complete View

Looking beyond CFFTs alone, the team identified five Umwelts to understand the biological elements of animal experience, which include: synchronization, revision, attention, persistence, and stability. They define synchronization as how an animal puts together the pieces of a single moment, revision as how perception is updated with fresh input, attention as how long focus remains on a single thing, persistence as how long content remains after a stimulus offset, and stability as how long it takes for perception to switch.

The researchers note that various studies have shown that single species display remarkably different performance measurements across these tasks, suggesting that, rather than relying on a single metric, such as CFFTs, to define how granularly an animal perceives time, different species exhibit distinct temporal experience organizations.

According to the team, temporal illusions are important for understanding how these elements vary in different species. By understanding where perception of time goes astray between input and recognition, researchers can gain a better idea of the processes the animal uses to construct its perception of time.

Time’s Illusions

These types of sensory illusions typically occur within a 100-450 millisecond time range in humans, such as apparent motion. When an object moves relative to the eye in such a brief time, it can appear to move even when it is stationary, an experience common to both vertebrate and invertebrate species. These illusions also occur in the auditory systems and the tactile systems that interpret an animal’s nervous system signals.

The researchers say that these Umwelts could be the root of understanding the phenomenology of time perception in animals. By better understanding these metrics, researchers could develop models of how they relate to one another and possibly even uncover aspects of temporal experience that don’t exist in humans.

Altogether, the researchers say their work can be used to explore consciousness from empirical, theoretical, and philosophical perspectives, and can also contribute to ecology by helping us better understand animals and their relationships to their environment, as well as the predator/prey relationship.

Additionally, a better understanding of these temporal experiences could inform infrastructure design, such as reducing avian collisions with wind turbines by increasing blade visibility to various bird species.

The paper, “Timescapes of Non-Human Experience,” appeared in Trends in Cognitive Sciences on June 17, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

A growing body of evidence suggests that leaving Earth may do far more than challenge the human body. According to a new study, the absence of gravity itself could temporarily reshape consciousness, loosening the brain’s most strongly ingrained assumptions and opening the door to altered perceptions, expanded awareness, and even experiences that resemble some aspects of psychedelic states.

As humanity prepares for longer stays on the Moon, commercial space tourism, and eventual missions to Mars, researchers contend that understanding what happens to the mind in microgravity may be just as important as understanding the engineering that gets astronauts there. According to them, gravity may not simply keep people anchored to the ground—it may also help anchor human consciousness itself.

In a new paper published in Frontiers in Psychology, researchers Dr. Annahita Nezami and Dr. Elisa Raffaella Ferre of Birkbeck, University of London, explored decades of neuroscience, psychology, and spaceflight research to propose that Earth’s gravitational pull acts as a deeply embedded “super-prior” within the brain. By disrupting this ancient reference point, microgravity may trigger widespread changes across neural networks that underpin perception, self-awareness, and emotional regulation.

“Human consciousness has evolved under the constant pull of terrestrial gravity, yet its role in shaping perception and awareness has received limited theoretical attention,” researchers write. “As spaceflight transitions from short missions to long-duration habitation, understanding how consciousness responds to non-terrestrial gravity becomes increasingly urgent.”

Every human brain evolved under the constant force of Earth’s gravity. From before birth onward, sensory systems constantly rely on gravity cues to determine which way is up, where the body is in space, and how to interpret movement.

Researchers argue that this constant exposure has made gravity one of the brain’s most reliable assumptions. In the language of predictive neuroscience, the brain constantly generates expectations about the world and updates them using incoming sensory information. Gravity, they say, functions as a basic expectation—a “1G super-prior”—that helps stabilize consciousness.

Remove that constant, and things begin to change.

In orbit, vestibular signals from the inner ear become unreliable. Visual, proprioceptive, and balance information no longer align as the brain evolved to expect. The resulting mismatch generates anticipation errors, forcing widespread recalibration.

Those changes are already well documented among astronauts. Space travelers commonly experience spatial disorientation, altered body perception, sleep disturbances, mood swings, and, in some cases, feelings of depersonalization or derealization—states in which individuals feel separated from themselves or perceive their surroundings as unreal.

Astronauts have also reported more positive and profound experiences. Many describe feeling “unmoored,” “expanded,” and deeply interconnected with humanity, or overwhelmed by awe while viewing Earth from orbit. This phenomenon, known as the Overview Effect, has been associated with lasting shifts in values, increased environmental concern, and enhanced feelings of oneness.

The study suggests that these experiences might originate from the same neurocognitive processes triggered when gravity’s stabilizing role is weakened.

“By perturbing the most stable embodied reference – gravity itself – spaceflight offers a rare window into how fundamental expectations shape consciousness,” researchers write. “The loosening of perceptual boundaries in microgravity has been proposed as a neurocognitive foundation for the Overview Effect.”

Brain imaging studies lend support to the idea. MRI scans of astronauts before and after extended-duration missions have revealed structural changes, including fluid redistribution, enlargement of brain ventricles, and gray matter remodeling. Functional MRI studies have also found changes in connectivity among vestibular, sensory, and default mode network regions involved in awareness and the combining of internal and external information.

Especially intriguing are changes observed in the default mode network, a system involved in introspection, self-referential thought, and consciousness. Activity inside this network appears to diminish after spaceflight, with some changes persisting for months after astronauts return to Earth.

Electroencephalography studies have likewise detected reductions in alpha-wave activity during and after missions, another sign that brain function is being reorganized in response to microgravity.

These neural changes led the researchers to an unexpected comparison.

Many of the same large-scale patterns recorded after spaceflight resemble effects previously documented under psychedelic compounds such as psilocybin and LSD. In both situations, highly organized brain networks appear to loosen, while communication between previously separate regions increases.

Researchers stress that the mechanisms are entirely different. Psychedelics act through serotonin receptors, whereas microgravity represents an environmental disruption rather than a pharmacological one. Yet both seem to converge by weakening the brain’s highest-level assumptions and increasing the combination of sensory information.

According to researchers, this convergence phenomenon suggests that spaceflight could provide scientists with a natural, drug-free model for studying transformative states of consciousness.

The researchers argue that terrestrial gravity, microgravity, and psychedelic states may represent different conditions along a spectrum defined by the strength of the brain’s deeply ingrained “1G super-prior.” As that stabilizing role weakens, top-down constraints relax, potentially increasing neuroplasticity and mental flexibility.

The implications go beyond astronaut health. Understanding how consciousness changes in unfamiliar environments may provide new clues to the neural foundations of self-awareness. It could also prove increasingly important as private citizens spend more time in space and human settlements expand away from Earth.

Researchers suggest that microgravity offers scientists something that cannot be replicated on Earth—a chance to observe what happens when one of evolution’s oldest assumptions suddenly disappears.

“By situating consciousness in an environment for which evolution offers no precedent, spaceflight positions microgravity as a powerful natural neurocognitive catalyst for transformative experience,” researchers write. “In stepping beyond Earth’s gravity, we gain a unique vantage point from which to examine the contingent foundations of human awareness and the conditions under which it can be fundamentally transformed.”

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com