Neurogel

Neurogel is a fluid used as a brain-computer interface and preservation medium by missionaries of the Bright Way during interstellar voyages. Yinrih are incapable of losing consciousness without dying, making anesthetic technologies for preserving crew during slower-than-light interstellar travel such as hypersleep unusable.

Neurogel serves a number of functions. It suspends metabolism while keeping the brain and nervous system active, cushions the suspended person against high G-forces, and bridges the user's nervous system with the ship's computer without invasive implants.

Neurogel is contained within machines called metabolic suspension capsules or amnions. Missionaries are fully submerged in neurogel during transit. The amnion presents a simulacrum to the suspended missionary while accelerating their time perception in order to make the trip seem to pass more quickly.

This simulacrum can be addictive, and missionaries are rigorously screened, and undertake a regimen of prayer and meditation so they don't dissociate, believing the simulacrum to be reality and forgetting their identity in the real world.

The addictive nature of neurogel makes it an object of abuse by so-called gel-heads.