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