What is a near-death experience?

Out-of-body exper­i­ences, meet­ing deceased loved ones, see­ing a light at the end of a tun­nel… These images and sen­sa­tions are recoun­ted by people who have come close to the bound­ary between life and death. Near-death exper­i­ences only became of real interest to sci­ence in the 1970s, yet they are not that uncom­mon and they say some­thing about our con­scious­ness. After the pub­lic­a­tion of the book Life After Life, writ­ten by the Amer­ic­an doc­tor Ray­mond Moody in 1975, the first sci­entif­ic stud­ies were pub­lished. Interest in this phe­nomen­on has peaked over the last ten years. The Coma Sci­ence Group team has been study­ing near-death exper­i­ences for a dec­ade, with the aim of gain­ing a bet­ter under­stand­ing of consciousness.

Near-death exper­i­ences (NDEs) are altered states of con­scious­ness that can affect any­one, regard­less of age, sex or reli­gious belief or lack there­of. The team gathered around 2,000 testi­mon­ies from all over the world, with great­er rep­res­ent­a­tion from French and Eng­lish speak­ing coun­tries, in order to obtain a more pre­cise defin­i­tion. NDEs are rich and intense sub­ject­ive exper­i­ences, with clear pro­to­typ­ic­al ele­ments: an out-of-body sen­sa­tion, encoun­ters with entit­ies, some­times deceased people, and the vis­ion of a tun­nel with a light at the end. Each exper­i­ence is per­son­al and unique, but there are recur­ring ele­ments. It is these pro­to­typ­ic­al aspects that dif­fer­en­ti­ate NDEs from oth­er sub­ject­ive states, such as dream­ing, which is infin­itely vari­able. Usu­ally, these are pos­it­ive exper­i­ences, des­pite the context.

A wide vari­ety of states can lead to an NDE. Most often, the per­son is clin­ic­ally dead, i.e. in car­di­ac arrest, but coma, trauma, anaes­thesia or stroke can some­times be the cause of a near-death exper­i­ence. Indi­vidu­als may exper­i­ence this phe­nomen­on in oth­er con­texts where their life is not in danger: dur­ing faint­ing, in med­it­at­ive states, dur­ing intense anxi­ety or orgasm. In addi­tion, people with a tend­ency to exper­i­ence dis­so­ci­at­ive states are more prone to these phe­nom­ena. For example, they may per­form an action mech­an­ic­ally, without real­ising it, until they reach a more intense state, a feel­ing of leav­ing their body.

Near-death exper­i­ences have a sig­ni­fic­ant impact on people’s lives, and for the most part they are largely pos­it­ive. People report a reduced fear of death and a more altru­ist­ic, less mater­i­al­ist­ic and more spir­itu­ally ori­ented state of mind. How­ever, 10–15% of testi­mon­ies attest to neg­at­ive con­sequences. The exper­i­ence of an NDE is too extraordin­ary to be integ­rated into one’s life after­wards. This can lead to anxi­ety and post-trau­mat­ic stress. The num­ber of neg­at­ive NDEs may be under­es­tim­ated, as they are not neces­sar­ily shared. 

The Coma Sci­ence Group’s first task is there­fore to determ­ine the pre­cise char­ac­ter­ist­ics of near-death exper­i­ences. The labor­at­ory is also inter­ested in under­stand­ing the poten­tial neuro­physiolo­gic­al or cog­nit­ive basis for these phe­nom­ena. What hap­pens in the brain dur­ing a near-death exper­i­ence? Imme­di­ately after car­di­ac arrest, there is a peak in elec­tric­al activ­ity in the brain, which emits faster waves in cer­tain spe­cif­ic regions, includ­ing the tem­poro-pari­et­al region, the area asso­ci­ated with con­scious­ness. The brain would be in great pain, but just before and after the heart stopped, a spike in elec­tric­al activ­ity would allow an NDE to be gen­er­ated. This could be a defence mech­an­ism or a way for the brain to cope with this physiolo­gic­al suf­fer­ing. At the same time, cer­tain hor­mones or neur­o­trans­mit­ters, such as endorphins, seem to con­trib­ute to the feel­ing of well-being. How­ever, most of these explan­a­tions are merely hypo­theses. Although the phe­nomen­on is becom­ing bet­ter under­stood, there is still a great deal of research to be done to prove it.

To gain a bet­ter under­stand­ing of what hap­pens in the brain dur­ing clin­ic­al death, the research team stud­ied the elec­tro­en­ceph­al­o­grams (EEGs) of patients between life and death. The sci­ent­ists then gath­er testi­mon­ies from sur­viv­ing patients. In the labor­at­ory, they also work with psy­che­del­ic sub­stances to try to repro­duce sub­ject­ive exper­i­ences that resemble IMEs. To do this, healthy par­ti­cipants (with no par­tic­u­lar dis­orders and who have nev­er exper­i­enced an NDE) are giv­en a dose of dimethyl­trypt­am­ine (DMT), psilo­cybin or ket­am­ine. By cross-ref­er­en­cing the res­ults with those of a study car­ried out by experts in psy­che­delics at Imper­i­al Col­lege Lon­don, the sci­ent­ists observed sig­ni­fic­ant over­laps between exper­i­ences under DMT and dur­ing an NDE. The same images and sen­sa­tions recur, such as encoun­ters with entit­ies or a feel­ing of har­mony with one’s envir­on­ment. How­ever, one dif­fer­ence was noted: dur­ing an IME, people have the feel­ing of being on a fron­ti­er, par­tic­u­larly that of death. This feel­ing is less pre­val­ent with DMT.

Accord­ing to cur­rent research, an NDE is a form of hal­lu­cin­a­tion. It is a men­tal exper­i­ence with per­cep­tions dis­so­ci­ated from the phys­ic­al envir­on­ment. Nev­er­the­less, des­pite their recur­rent nature, there are still many unknown ele­ments about the brain, death and con­scious­ness. This defin­i­tion could there­fore be called into ques­tion tomor­row. Explain­ing near-death exper­i­ences would give us a bet­ter under­stand­ing of con­scious­ness, its ori­gin and its construction.

Sirine Azouaoui