According to research, the absence of Earth’s gravity can temporarily disrupt familiar perception mechanisms and trigger profound shifts in self-awareness
As preparations for long-duration missions to the Moon and Mars continue, scientists are increasingly focusing not only on astronauts’ physical health but also on how the brain operates in space. In a new study, researchers from Birkbeck College at the University of London have proposed that gravity plays a far more important role in consciousness than previously recognized. They suggest that the lack of normal gravitational pull may temporarily weaken deeply ingrained perception processes and lead to states vaguely reminiscent of some effects associated with psychedelics.
Annahita Nezami and Elisa Raffaella Ferre examined data from neuroscience, psychology, and space medicine. They view Earth’s gravity as one of the foundational reference points the brain uses to construct its understanding of the world. From birth, the balance organs, vision, and body position sensations constantly rely on the direction of gravitational force to help determine spatial orientation and interpret movement. In modern neuroscience terms, this is considered a fundamental “super-priority” that the brain depends on when shaping conscious experience.
In weightlessness, signals from the inner ear no longer match the expectations developed through evolution. A conflict arises between information from the balance organs, vision, and muscles, forcing the brain to reorganize its functioning. Astronauts have long reported spatial disorientation, sleep disturbances, mood swings, altered body perception, and even episodes of depersonalization—where a person feels detached from their own identity or perceives the surrounding world as unreal.
At the same time, many space travelers describe positive experiences as well. Observing Earth from orbit often triggers the “Overview Effect”—a profound sense of unity with humanity, intense emotional impact, and a shift in life values. Scientists propose that this phenomenon may stem from the same neurocognitive processes activated when gravity’s influence diminishes.
This hypothesis is supported by data from magnetic resonance imaging and electroencephalography. After extended missions, astronauts showed fluid redistribution within the skull, changes in gray matter, and reorganization of connections between different brain regions. Particularly intriguing were alterations in the default mode network—a system linked to self-awareness, internal dialogue, and reflection on personal experience. Some of these changes persisted for months after returning to Earth.
The authors note that similar shifts in brain activity have been previously observed under the influence of psilocybin and LSD. However, the mechanisms differ entirely: psychedelics act on serotonin receptors, whereas weightlessness is an external environmental factor. Yet in both cases, the most stable perception patterns weaken, while interactions between various brain regions intensify.
Scientists believe that spaceflight could serve as a unique natural laboratory for studying the nature of consciousness without the use of drugs. This could prove valuable not only for future colonists on the Moon and Mars but also for a fundamental understanding of how human perception of the self and the world around us develops.
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