“The Enigma of Consciousness and the Mind-Brain-Reality Relationship: Scientific and Epistemological Implications of the Phenomenology of Consciousness Between Ordinary States, Near-Death Experiences (NDEs), and Other Non-Ordinary Expressions of the Mind” Near-Death Experiences (NDEs) are defined as the memory of impressions that occurred in critical conditions with loss of consciousness, including elements such as the experience of leaving the body, the vision of a tunnel with or without a light at the end, of deceased relatives, the encounter with superior entities and a review of one's life in a climate of profound serenity and well-being. The most critical and embarrassing aspect is their transcendent content, which the dominant culture tends to consider a priori as a hallucinatory phenomenon, a mere expression of an organic brain disorder. Several scientific interpretations are now available, including: a) Concentric retinal ischemia as a trigger of tunnel vision; b) intracellular electrolyte alterations; c) release of endogenous opioids; d) delirium; e) relationship with hallucinogen receptors; f) temporal lobe epilepsy; g) alterations of the right temporoparietal junction; h) residual brain activity during cardiac arrest; i) REM sleep intrusions; l) expectations of the afterlife. However, all these interpretations still remain hypotheses without any proof, while some of them can be refuted on the basis of other known facts; furthermore, their phenomenology is completely different from that of the delirium observed in intensive care. Finally, individual cases rigorously documented in the international scientific literature have demonstrated the possibility of correctly perceiving the facts that occurred in the resuscitation room during cardiac arrest in the context of an out-of-body experience. A large body of philosophy and literature has contemplated the moment of passing away and the period immediately following since ancient times with some elements that recall those well described today in the scientific literature on NDEs, from the Egyptian Book of the Dead, to the Bardo Throtol (the Tibetan Book of the Dead) to Plato's myth of Er (Republic X, 614-621), while references to the vision of light or the review of one's life can be found in literature from Homer to Dickens to Milan Kundera. NDEs therefore constitute a complex and fascinating topic, still far from understood and endowed with profound epistemological implications; their phenomenology in fact challenges current scientific knowledge on the physiology of the brain and the mind, posing new questions on the nature, physiology and physiopathology of consciousness and the psyche, on the still mysterious mind-brain relationship and on the mind-reality relationship.