Astral projection, like all spiritual experiences, occur as hallucinations, primarily in the amygdala, and temporal lobes of the brain.
What people practice in real life is hallucinogenic induction, by several different means. They all do pretty much the same thing; poison and/or chemically overload one or more parts of the brain. The temporary “silence” creates the impression of superiority of some ability or sensation.
This is a cognitive illusion, as the “silence” of the disabled or damaged part of the brain, makes what areas of the brain that are still functional, only seem much “louder”.
Most types of brain damage from induced cognitive distortion, (getting high) never heal.
Please work a bit more on learning to discern between fantasy and fact.