What Do Near-Death Experiences Tell Us?

Near-death experiences tell us something real and something limited. They show that people whose bodies are in grave danger can have vivid, deeply meaningful experiences, often of light, peace or leaving the body, that they remember for years. They do not, by themselves, show what causes those experiences or what happens after death. Scientists are still debating both.

Those two ideas fit together. You can take someone’s experience completely seriously and still be careful about what it proves. That is how this article approaches the subject.

What do people report?

A near-death experience, or NDE, is a vivid experience reported by some people who came close to dying. Much of the research focuses on cardiac arrest, when the heart suddenly stops pumping blood. A 2025 review in Nature Reviews Neurology describes NDEs as episodes of “disconnected consciousness” with rich, often mystical content.

Accounts vary, but some features come up again and again. A summary from the University of Liège, where that review was led, lists the sense of leaving the body, visions of intense light and deep feelings of peace. A team led by resuscitation researcher Sam Parnia of NYU Langone Health adds a heightened, lucid inner experience and a life review, in which people look back on how their actions and intentions affected others. That team prefers a different name, “recalled experiences of death,” a term it says a consensus of scientists proposed as more accurate.

Not every account is pleasant. In the first AWARE study, described below, some survivors’ memories involved fear, or scenes of violence or persecution. Many people say the experience changed them. A Dutch study that followed survivors for eight years found that this change often unfolded over several years.

How common are they?

It depends on who is asked and how an NDE is defined. In a well-known Dutch study published in The Lancet in 2001, 62 of 344 cardiac arrest survivors (18%) reported an NDE. In the first AWARE study, about 9% of survivors who gave detailed interviews did. A 2010 Slovenian study found 21%. Across these studies, roughly 9% to 23% of cardiac arrest survivors report one.

NDE-like experiences are not limited to hospitals. A 2019 online survey of 1,034 people in 35 countries found that about 10% reported one at some point. It used a standard questionnaire called the Greyson NDE Scale.

What did the AWARE studies find?

AWARE stands for AWAreness during REsuscitation. These hospital studies tried to move beyond stories by testing awareness during cardiac arrest itself.

The first AWARE study, published in 2014, covered 2,060 cardiac arrests. Of the 101 survivors who completed detailed interviews, 46% had some memories, 9% had NDEs, and 2% described seeing and hearing real events during their resuscitation. The team reported one case with a verifiable period of awareness at a time when brain function was not expected.

AWARE II, published in 2023, went further. At 25 hospitals, researchers ran a hidden test during CPR, using a computer to show images and headphones to play sounds. They also recorded brain waves and brain oxygen. Of 567 cardiac arrests, only 53 people survived, and 28 completed interviews. Eleven recalled memories or perceptions that suggested some awareness. Six described a transcendent experience of death. None identified the hidden image. One identified the sound.

The brain recordings were striking. Even though oxygen levels in the brain were very low, brain-wave patterns like those of a normal, conscious brain sometimes appeared as late as 35 to 60 minutes into CPR. The authors concluded that consciousness and thinking may occur during cardiac arrest. Because so few patients survived, the numbers remain small.

What could explain them?

Several brain-based explanations have some evidence behind them. None has been shown to explain everything.

• Oxygen and carbon dioxide. When blood flow fails, the brain gets less oxygen (hypoxia) and carbon dioxide builds up (hypercapnia). In a 2010 study of 52 cardiac arrest survivors, those with higher carbon dioxide levels were more likely to report an NDE.
• Dream sleep slipping into waking. REM sleep is the stage when most vivid dreams happen. Sometimes its features, like dream images or brief paralysis, intrude on waking moments. In the 2019 survey, 47% of people who reported NDEs also reported this kind of REM intrusion. Among people with no NDE-like experience, it was 14%.
• Brain chemistry. The 2025 review proposed a model called NEPTUNE. It describes a cascade: falling blood flow brings low oxygen, high carbon dioxide and acid build-up, while overexcited brain cells disrupt the brain’s chemical messengers. The authors suggest serotonin may play a double role, bringing calm through one receptor and vivid visions through another. That links NDEs to research on mystical experiences caused by psychedelic drugs.
• Old survival responses. The same review suggests NDEs may have roots in ancient threat and coping responses. It adds that some people may be more prone to them, such as those who easily feel detached from their surroundings.
• A final surge. Studies in animals, and in two of four dying patients in a 2023 study, found a burst of fast gamma brain waves as oxygen fell. It included a region some scientists see as key to conscious experience.

What remains unexplained?

Quite a lot. The Dutch Lancet study found that NDEs were not linked to how long the heart was stopped, to medication, or to fear of death beforehand. Its authors argued that if lack of oxygen alone caused NDEs, most people who were clinically dead should report one. Only a minority do. Why some people have them and others do not is still unclear.

Timing is another puzzle. Does the experience happen during the arrest itself, or as the brain restarts during recovery? The 2025 review suggests that studying how brain activity slowly returns after resuscitation could help researchers find the brain activity behind NDEs.

Underneath it all sits a bigger unknown: how brain activity produces experience in the first place. Our article on consciousness explores that question. Scientists disagree here too. After the NEPTUNE model appeared, Parnia’s group replied in the same journal, calling for research “without prejudice” and stressing that these experiences follow a consistent pattern. The debate is far from settled.

What would change the answer?

A few kinds of results would shift the debate:

• Verified perception. If people with no signs of consciousness could reliably identify hidden images or sounds, with the timing confirmed by monitors, that would be very hard to explain as a memory built later. So far, AWARE II found no hits for images and one for sound.
• Reliable prediction. If measurements such as carbon dioxide levels or brain-wave patterns could predict who will have an NDE, and what it will contain, the brain-based view would grow much stronger.
• Bigger, repeated studies. Most findings so far come from small groups. Larger studies that repeat results would matter more than any single striking case.

Our guide to what would count as evidence explains why claims like these need careful tests. Our companion piece, What Happens When We Die?, looks at what medicine can and cannot say about the end of life.

If this subject touches a recent loss, or a frightening experience of your own, you don’t have to sort it out alone. In the U.S., you can call or text 988 to reach the 988 Suicide & Crisis Lifeline. It is free, confidential and open around the clock, and you do not need to be in crisis to reach out.

If you or someone you love has had a near-death experience, it was real as an experience: felt, remembered and often life-changing. Honoring it does not require deciding what caused it. The best science so far offers partial answers, strong clues and open doors. Keep asking what these experiences mean, and keep listening to the people who have them.