I was born almost strangled. Spent the first minutes of life without oxygen. I do not remember it, but I know what clinical death is from other causes — not from personal experience, but from several dozen read and cross-checked reports.
The near-death experience (NDE) is one of those phenomena around which "paranormals" and "materialists" long ago dug trenches and shoot at each other. Rarely does anyone stand on the field and speak in a normal voice. Let me try.
What is actually observed
The classic NDE set: out-of-body, movement through a tunnel, light, meeting with the departed, life review, return. Not in everyone. In a small but stable share of people who survived cardiac arrest or another near-death state. Per the meta-analysis Parnia et al. (2014, Resuscitation): around 9–18% of cardiac arrest survivors report some form of NDE.
A well-documented phenomenon. The issue is not whether it occurs. The issue is its interpretation.
What neuroscience says
Today we have several neurobiological mechanisms, each explaining part of NDE:
— Hypoxia and reperfusion. Under oxygen starvation, some visual cortex cells start firing chaotically, subjectively experienced as "a tunnel with light at the end". Shown in clinical and experimental work (Blackmore, 1993; Nelson et al., 2006).
— DMT and endogenous psychedelics. Rick Strassman proposed the brain releases its own DMT during dying. Experimentally not confirmed in humans yet, but DMT has been detected in rat pineal gland (Nichols et al., 2018).
— Gamma activity burst before death. Lempert et al. (1994), then Borjigin et al. (2013, PNAS): in the final seconds of life EEG records a brief gamma surge, particularly in regions linked to perception and memory. The brain "switches on" one last time at unprecedented intensity. Hypothetically this accounts for the "heightened awareness" many survivors report.
— REM intrusion. Nelson et al. (2006): people with NDEs show REM intrusions into wakeful states more often. The hypothesis is that NDE is a variant of REM dreaming in extreme conditions.
No single mechanism explains the full NDE. Taken together, they explain most of what survivors report.
What neuroscience does not know
The honest edge.
Reports of accurate resuscitation details perceived "from above" (so-called veridical perceptions) are methodologically difficult. Pim van Lommel (Lancet, 2001) assembled a Dutch cohort of 344 patients; 18% reported NDEs, some with verifiable details. But the AWARE protocol (Parnia et al., 2014), designed specifically to test "from above" perception, gave modest results: of 101 cardiac patients, only one recalled an event independently verifiable.
That does not mean veridical perceptions are a myth. It means their rarity and reproducibility difficulty should make us cautious.
Also open: long-term personality shifts. Many NDE survivors report radical changes in values, reduced fear of death, altered attitude to work. This is statistically testable. And confirmed. But may be explicable as a PTSD-like reorganisation after extreme experience, rather than "contact with another reality".
What I think
Three levels.
Established: NDE is a real neurocognitive phenomenon. Has a characteristic phenomenology. Appears in 9–18% of surviving cardiac arrests. Has long-term personality consequences.
Preliminary: part of the phenomenology (tunnel, light, life review) is explained by known neurobiological mechanisms. The terminal gamma burst may be a key to the "heightened consciousness" report.
Speculation: veridical perceptions, if they really exist, may indicate something beyond the standard model of consciousness. Or they may be an artefact of memory reconstructed in hindsight from available fragments. Right now the honest answer is "I don't know".
In the Neural Cosmology frame, NDE is an interesting boundary case. If consciousness is an information-processing local node in a larger network, then what happens at the moment the node exits the network? The standard interpretation: the process stops. The non-standard: for a brief instant the node loses its "filter" and sees something normally inaccessible.
I honestly don't know which of the two is right. And while the "I don't know" stays, I keep the door ajar. Only ajar — so no draft blows in from the neighbouring office where they sell "contact with spirits" for $150.