Changes in felt gravity from Memantine

Changes in felt gravity can be described as the experience of the perceived direction or intensity of gravitational pull being altered in a way that does not correspond to one's actual physical orientation. During this state, a person may feel as though they are floating upward, sinking downward, being pulled sideways, tilting at unusual angles, or drifting through weightless space. The effect arises from a disruption in the brain's proprioceptive and vestibular processing systems, which normally provide a constant, unconscious awareness of one's orientation relative to the earth's gravitational field.

The subjective quality of this effect varies considerably. Some users describe a gentle floating sensation, as if gravity has simply been reduced and they are slowly lifting off the ground or their bed. Others experience a more dramatic sense of falling or being pulled in a specific direction, which can produce a rollercoaster-like sensation of acceleration. In its most extreme form, the concept of "up" and "down" may become entirely meaningless, with the person feeling as though they exist in a directionless void where spatial orientation has no fixed reference point. Some report a sensation of being gently rotated or spun, while others feel that the room itself is tilting around them.

Changes in felt gravity are most commonly induced under the influence of moderate to heavy dosages of dissociative compounds such as ketamine, DXM, PCP, and diphenidine, where the progressive disconnection from bodily sensation naturally disrupts the proprioceptive cues that ground one's sense of spatial orientation. The effect is also produced by psychedelic compounds, particularly at higher doses of LSD, psilocybin, and DMT, as well as cannabinoids and Salvia divinorum, which is particularly noted for producing dramatic gravitational distortions and the sensation of being pulled in unusual directions.

The experience often has a profound impact on the overall character of the altered state. The loss of one's normal gravitational reference can contribute to a sense of leaving the body, floating through space, or entering other dimensions. In dissociative hole experiences, changes in felt gravity often combine with visual and spatial hallucinations to create the impression of moving through vast architectural spaces, falling through infinite voids, or soaring through cosmic landscapes. The vestibular disruption can also contribute to physical discomfort in some users, producing dizziness or nausea, particularly when the felt gravitational changes conflict with visual information.

Subjective reports frequently describe this effect as one of the more remarkable and memorable aspects of the dissociative experience. Users often report that the sensation of weightlessness or gravitational shifting produces a childlike sense of wonder and delight, comparing it to floating in water, riding a roller coaster, or the moments of freefall during a dream. Others find the experience disorienting or unsettling, particularly when it is accompanied by dizziness or when the gravitational shifts are rapid and unpredictable.

Changes in felt gravity are often accompanied by other coinciding effects such as physical disconnection, dizziness, internal hallucination, and derealization. The combination with physical disconnection creates a compound effect where not only does gravity feel altered, but the body itself feels remote or absent, amplifying the sensation of floating or drifting through space. When experienced alongside vivid internal hallucinations, the gravitational changes often become integrated into the hallucinatory content, making the imagined environments feel physically real.