The term out-of-body experience was introduced in 1943 by George N. M. Tyrrell in his book Apparitions,[1] and was adopted by researchers such as Celia Green[2] and Robert Monroe[3] as an alternative to belief-centric labels such as "astral projection", "soul travel", or "spirit walking". OBEs can be induced by brain traumas, sensory deprivation, near-death experiences, dissociative and psychedelic drugs, dehydration, sleep, and electrical stimulation of the brain,[4] among others. It can also be deliberately induced by some.[5] One in ten people have an OBE once, or more commonly, several times in their life.[6][7]