A Near-Death Experience (NDE) is a distinct subjective experience that some people report after a near-death episode, which is defined as either: when a person is clinically dead, near-death, or in a situation where death is expected. The earliest known description of a near-death experience was a recount by Plato in his Myth of Er, (circa 420 BC). However, it wasn’t until 1975 that Dr. Raymond Moody coined term near-death experience. (IANDS, 2016).

According to Rivas et al. (2016), one of the central discussions surrounding NDE research is whether they signal the existence of a broader reality, indicating that there may be more going on than just imagination. Greyson (2015), outlines two types of paradigms that attempt to explain NDEs: the mechanistic- reductionist paradigms which include psychological and physiological explanations; and a non-reductionist paradigm, which essentially entertains the notion of post-mortem survival, that is that some aspect of consciousness survives after physical death. This is also known as the survival hypothesis (Irwin & Watt, 2007).

Let us first explore the mechanistic-reductionist paradigms, starting with the psychological explanations. There have been a number of psychological explanations put forward to explain NDEs (Greyson, 1983; Greyson, 2015):


It has been suggested that NDEs are a form of depersonalization. (Noyes & Kletti, 1976; Noyes & Kletti, 1977; Noyes, 1979; Noyes &Kletti, 1981). Depersonalization is when an individual loses all sense of identity, with their thoughts and feelings seeming unreal. It also includes a psychological detachment from their body, which is seen as a defence mechanism in response to perceived threat of death (Greyson, 2015; Irwin & Watt, 2007). Noyes (1979) however, has highlighted that the depersonalization model does not account for all NDE phenomena. In fact, some NDE characteristics represent a complete contrast to this model. For example, Irwin & Watt (2007) point out a key difference in that depersonalization also includes confusion over self-identity and reality, but in contrast, this is not the case with near-death experiencers, who have reported feeling a strong sense of self and mental clarity – more so than in waking consciousness.  Holden et al (2009) have also found that near-death experiencers as a group have been found to be psychologically healthy and are similar to the general population in many regard.


Dissociation is a psychological defence mechanism that is triggered in order to deal with pain or anxiety. In a study carried out by Greyson (2000), it was found that the dissociative symptoms in near-death experiencers were not consistent with a psychiatric disorder, but rather with non-pathological responses to stress. I have also observed this in my own experience. Having worked with many dissociated patients and a few near-death experiencers over the years, it seems that dissociation as a model again cannot account for the full range of NDE phenomena, as is the case with depersonalization.

The Expectancy Model

The notion that individuals replace an unpleasant reality, (such as fatal danger) with a pleasant fantasy in order to avoid an emotional freeze response ties in with the expectancy model which also postulates that NDEs are defence mechanisms protecting against the threat of death, but the model additionally adds that these are imagined constructs built from one’s personal and cultural expectations (Greyson, 2015). However, there have been a number of studies which challenge the expectancy model. A Study carried out by Abramovitch (1988), found that there was a conflict between the reported NDE and the cultural expectation, which led to the individual feeling confused about their NDE. Additionally, Athappilly et al. (2006) found that NDEs reported before 1975 (which was when the term “near-death experience” was coined) did not substantially differ from those collected post 1975. They concluded that their data challenged the hypothesis of prevailing cultural models influencing NDEs. NDEs in children also challenge the expectancy model as they may not yet have fully constructed their own personal, cultural and religious expectations. Despite this, it has been found that NDEs reported by children are similar to those reported by adults. (Bush, 1983; Morse et al., 1985).

Other psychological explanations

Other psychological explanations include post-traumatic stress disorder (Greyson, 2001), fantasy proneness (Irwin &Watt, 2007), recollection of birth memories and autoscopy (Greyson, 2000). However similar to the discussion above, none of these theories account for the full range of NDE phenomena (Greyson, 2000; Greyson, 2001; Irwin & Watt, 2007).

The second type of mechanistic-reductionist paradigm are the physiological explanations:

Cerebral anoxia

Cerebral anoxia is one such theory put forward which accounts for NDEs by suggesting that they are a result of an oxygen shortage in the brain (Blackmore, 1993). However, van Lommel et al. (2001) point out that most patients that have been clinically dead should report an NDE if this was the case, yet only a few do. Additionally, Parnia et al. (2001) have found that oxygen levels were higher in those that experienced NDEs. It should be noted however, that Braithwaite (2008) has put forward an argument stating that van Lommel’s conclusion regarding cerebral anoxia was over simplified, and did not account for the different types of cerebral anoxia which produce a wide range of neurophysiological consequences.

Temporal lobe paroxysm

In addition to cerebral anoxia, it has also been suggested that NDEs are a result of temporal lobe paroxysm, a seizure-like neural function or the result of direct electrical stimulation to the area (Greyson, 2015; Irwin & Watt, 2007). This produces out-of-body and autoscopy experiences, as well as illusionary body displacement sensations (Blanke et al., 2002; Blanke et al., 2004). However, a few key differences have been observed. For example, temporal lobe seizures frequently produce distortion of the immediate environment along with feelings of loneliness and sadness, which is different to NDEs, in which feeling of peace and calm are commonly reported. Additionally, electro-cortical stimulation or seizures do not produce the communication with deceased relatives, as do some NDEs (Irwin & Watt, 2007).

Chemical release models

Chemical release models (such as neurotransmitter and endorphin release) are another suggested cause for the occurrence of NDEs (Saavedra-Aguilar & Gomez-Jeria, 1989; Jansen, 1997). However, Sabom (1982) has argued that the known effects of endorphins last longer than the typical and NDE; and additionally Fenwick (1997) has highlighted that Jansen’s hypothesis contains several weaknesses, for example, contrary to Jansen’s proposal, some individuals experiences NDEs that are unlikely to upset cerebral physiology. Once again, it has been suggested that this theory does not accommodate all aspects of NDEs (Irwin & Watt, 2007).

Cardiac arrest model

An important area of current research is the cardiac arrest model. Researchers have found that a small number cardiac arrest survivors have reported memory recall (from during the event), which is consistent with NDEs (Parnia & Fenwick, 2001; Parnia et al., 2014;). During a cardiac arrest, the cortical brain activity shuts down within around fifteen seconds (resulting in a flat electroencephalogram EEG reading), to a point where complex conscious processing is no longer possible (Rivas et al., 2016), hence posing the question of how people are able to recall experiences. Braithwaite (2008) however, argues that a flat (EEG) reading (assuming no technical error) does not necessarily indicate total brain inactivity, and suggests that deep sub-cortical brain structures could still be active, which may account for some of the occurrences. Additionally, Chawla et al. (2009) reported that there was a very brief surge in electrical brain activity at time of death, which they suggest could be responsible for the occurrence of NDEs. On a similar note, Borjigin et al. (2013) found a surge in electrical brain activity in rats within the first 30 seconds of cardiac arrest, which they too, suggest is a possible cause for NDEs. However, Greyson (2015) highlights that the electrical activity is very small in relation to the brain activity observed before the arrest, and hence is unlikely to account for NDEs. He also noted that this experiment was conducted with rats and may not necessarily be accurate in the case of humans.

The timing of an NDE in relation to cardiac arrest also needs to be considered. NDEs are commonly associated with clarity of thought, therefore Parnia & Fenwick (2002) have argued that NDEs cannot occur during the cardiac arrest recovery period as this is commonly associated with confused thinking; and neither can they occur when the person starts to go unconscious as this happens too quickly. French (2005) challenges this notion, highlighting that some researchers still argue that there is a possibility of the NDEs occurring during both the periods mentioned above. The cardiac arrest model also raises the question of why such few survivors of a cardiac arrest experience NDEs, although it is thought that age may play a part. (van Lommel, 2001).

The fact that near-death experiencers report vivid sensory imagery, mental clarity and clear memory, presents a challenge for the mechanistic-reductionist theories because these characteristics are inexplicable if viewed from the perspective that consciousness is an epiphenomena of the brain (Greyson, 2015; Laszlo & Peake, 2014). This has led to some researchers proposing a non-reductionist theory, which suggests that consciousness is not a by-product of the brain, but is rather received by the brain (Grosso, 2015; Goswami & Pattani, in prep; Lorimer, 1984). Van Lommel (2001) has also proposed that, “complete and endless consciousness is everywhere in a dimension that is not tied to time or place, where past, present and future all exist and are accessible at the same time” (p.xvii).

Veridical studies

This theory is supported by veridical studies, which, according to Rivas et al. (2016), minimise the possibility of inaccurate or fabricated accounts. In their recently published book, the authors present 104 independently corroborated cases. They consider a number of different cases which include after-death communication with strangers, and NDEs during cardiac arrest. They also specifically excluded cases that lacked sufficient evidence to suggest that the NDE took place during the time of clinical death. After careful consideration of the reductionist argument, they concluded that consciousness has the “ability to function independently of the brain, and hence is a phenomenon that is independent of the brain” (p.219). Similarly, Holden et al (2009) reviewed 93 cases of out-of-body experiences in NDEs. Eighty of these cases were corroborated independently, and it was found that 92% of these were accurate.

Another factor that strengthens the non-reductionist view and potentially provides evidence for post-mortem survival is communication with deceased relatives or friends during the NDE, particularly where the experiencer meets an unknown person whose identity is later confirmed by living friends or relatives (Alexander, 2012; Rivas et al., 2016; Sartori, 2015); or in cases where the experiencer reports back information that they could not have previously known, for example, meeting a deceased person who they did not know had died. A combination of veridical cases and meeting deceased friends or relatives challenges the reductionist notion that NDEs are a hallucination. (Greyson, 2015).

NDEs and blind participants

Ring & Cooper (1997, 1999) conducted a study in which 80% of the blind participants reported an NDE/OBE, during which they experienced visual perception; however, not all the cases were independently corroborated. The authors do discuss some possible explanations for apparent sight in the blind and consider both the dream hypothesis, which they reject, as well as Blackmore’s (1993) retrospective reconstruction theory, which suggests that participants reconstruct a plausible account based on various other perceived cues. The authors commented that although Blackmore makes a plausible argument, they could see no evidence of it amongst the study participants (Ring & Cooper, 1997).

NDE after-effects

Another area that potentially strengthens the non-reductionist argument are the after- effects that are experienced by near-death experiencers. Whilst it has been argued that some of these changes, such as a spiritual transformation may have come about due to unconsciousness processing (hence indicating a psychological explanation for their occurrence), after-effects such as miraculous healing (P. Sartori, personal communication, 16th August 2013), psychokinetic abilities and unintentional poltergeist-like influences seemingly provide an argument in favour of the non-reductionist view (Rivas et al., 2016).

One of the potential issues with NDE research is methodology, especially since NDEs are an unpredictable occurrence. For example, psychological hypotheses cannot give an indication of what processes and defences were operating at the time of the experience, but rather they can only test cognitive and personality traits of the experiencer. Similarly, methodological sophistication limits the extent to which physiological theories can be tested (Greyson 2015). Another factor to take into consideration is the researcher’s own belief system whilst processing another’s NDE, and to what extent this could create a bias. (NDERF, 2016). Rivas et al. (2016) however, make an interesting point by highlighting that although strictly controlled experiments are very conducive, anecdotal evidence is not necessarily unscientific, especially in the case of veridical studies.


Whilst the psychological and physiological approaches presented some plausible explanations for some of the NDE features, it appears that none of the models were able to account for the full range of NDE phenomena. Furthermore, just because the reductionist explanations may be valid in certain circumstances does not necessarily mean that NDEs are not a “real phenomena”. The reductionist models however do raise an interesting question as to why such few people experience an NDE, especially in relation to the cardiac arrest model.

From the critical evidence presented, it seems that the non-reductionist model significantly challenges the reductionist worldview. Moreover, other findings in parapsychology, such as biocommunication with plants (Backster, 2003), non-local communication in correlated brains (Grinberg-Zylberbaum et al., 1994), and the effects of remote prayer on bloodstream infection (Leibovici, 2001) further strengthen the non-reductionist notion. Additionally, advances in quantum physics in recent years have also presented anomalies which question whether the materialistic world-view represents the complete scientific picture (Goswami, 2008; McEvoy & Zarate, 1996).

Although there are some valid arguments raised from both sides, it is evident that the non-reductionist model questions the current scientific paradigm. I have been using parapsychological research to inform my psychotherapy practice for some time and I find it immensely useful when working with bereavement or anxiety surrounding death. Whilst the “hard-problem” of consciousness still remains unresolved and ongoing research needs to be conducted, a fair representation of the arguments presented need to be more prominently included in current training and education.


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