The various states of altered consciousness are presented together with a short resume of the history and the main research results in the area. UNIO MYSTICA - the mysterious experience of unity is thereafter explained in more detail. The phenomenology of the experience is elucidated and a distinction between the contents and thequality of the experience is introduced. Furthermore the conditions linkage to psycho-physiological, somato-psychic and psychological functional processes are discussed. Finally the ontological status ofthe experience and its importance for our understanding of the human consciousness are encircled.Den ændrede bevidstheds forskellige tilstande præsenteres og en kort gennemgang af områdets historie og væsentligste fo...