Robert Monroe, a radio executive who began having spontaneous out-of-body experiences in 1958, did more than anyone to bring astral projection out of occult literature and into a modern, ostensibly technical idiom. His Monroe Institute, founded in Virginia, developed Hemi-Sync, paired tones played separately to each ear that are claimed to synchronise brainwave activity and ease the transition into an out-of-body state, and it has run residential programmes on that basis for decades. Parapsychologists took the claim seriously enough to test it: experiments asked projectors to identify a hidden target, a number or an image placed in another room, while apparently out of body, and results have been mixed and none has been independently replicated to a standard that satisfies mainstream science.
Neuroscience offers a competing account that does not require anything to leave the body at all. Out-of-body experiences can be induced in a laboratory by disrupting the brain's usual integration of vision, touch and balance, most famously by stimulating the temporoparietal junction, and similar sensations occur reliably during sleep paralysis, in the hypnagogic state between waking and sleep, and near death. Believers and researchers on the sceptical side agree on the phenomenology, that people vividly experience separating from the body, and disagree entirely on what that experience is evidence of. Between the two positions sits the practice itself, taught today largely through the same relaxation, breath and visualisation methods older occult manuals describe, now packaged as a skill anyone can learn rather than a rare gift.