Some people who survive cardiac arrest describe vivid experiences from a time when they appeared unconscious. Dr Sam Parnia has spent more than two decades trying to investigate those accounts. His studies ask what survivors remember, whether they could perceive events around them, and what their brains were doing during attempts to save their lives.

Research reviewed to 17 September 2026.

When a survivor describes watching the medical team from above, encountering a brilliant light or reviewing events from their life, how should that account be understood? Listening establishes what the person remembers. Finding out when the experience occurred, and how it became possible, requires a different kind of investigation.

Dr Sam Parnia, a physician and researcher at NYU Langone, approaches these questions through resuscitation medicine: the care of people whose circulation has failed and who may be revived. His laboratory works on improving survival and preventing brain injury, alongside its research into consciousness. Understanding a survivor’s experience is part of that broader concern with what happens to the person during and after treatment. About the Parnia Lab.

Parnia’s best-known projects, the AWARE studies, bring together three kinds of evidence. Researchers interview survivors, introduce pictures and sounds that might later be recognised, and use instruments to record aspects of brain function. Each method answers a different question. Much of the interest—and difficulty—lies in connecting their results.

What happens when the heart stops?

In cardiac arrest, the heart stops pumping blood effectively. The brain loses its normal supply of oxygen, and the person usually becomes unresponsive very quickly. Cardiopulmonary resuscitation, usually shortened to CPR, uses repeated chest compressions to move some blood through the body while rescuers try to restore effective circulation. A defibrillator may also deliver an electrical shock when the heart’s rhythm is one that can be treated in this way. American Heart Association: cardiac arrest explained.

Because CPR can supply some blood to the brain, a stopped heart does not tell us exactly how much brain function remains during treatment. This is one reason researchers need measurements as well as observations of whether a patient moves or responds.

Cardiac arrest is also different from brain death. A diagnosis of death using neurological criteria requires an irreversible loss of the capacity for consciousness and spontaneous breathing. The people interviewed in Parnia’s studies survived a potentially reversible interruption of circulation; they had not recovered from properly diagnosed irreversible brain death. Keeping that distinction in mind helps us understand what reports of consciousness “after death” actually refer to. NHS Blood and Transplant: death diagnosed using neurological criteria.

The experiences that prompted the research

Survivors’ accounts can include a sense of separation from the body, unusual peace and clarity, light, encounters understood as meetings with deceased relatives, and a review of their lives. A life review can mean more than remembering a sequence of events: people describe considering their actions, intentions and treatment of others. Some also report seeing or hearing details of the medical treatment taking place around them. Parnia Lab: accounts of consciousness around cardiac arrest.

These descriptions raise related but distinct questions. An account of peace or a life review invites investigation into the person’s inner experience. A claim to have seen something in the hospital room offers the possibility of checking the account against an event outside the person’s memory. Neither kind of account should be silently substituted for the other.

Parnia and colleagues have also tried to make the language of research more precise. In 2022, they proposed the term recalled experience of death for a particular kind of vivid, often transformative recollection associated with a life-threatening event. Their framework describes recurring themes such as separation from the body, movement towards a destination, life review, a sense of being home and a return to ordinary life. It distinguishes these from conventional dreams, confused experiences during severe illness and memories of waking in intensive care. Parnia and colleagues’ 2022 research framework.

The proposed definition is debated. For example, other researchers question whether frightening experiences should be excluded from this category or attributed to confusion. That disagreement matters: the definition chosen will affect which accounts a study counts as near-death experiences. The framework represents an attempt to organise research, rather than a definition accepted by everyone in the field. Martial and colleagues’ response.

Beginning with hospital survivors

One of Parnia’s early studies, published in 2001, followed cardiac-arrest survivors at Southampton. Researchers interviewed 63 people and assessed their accounts using the Greyson Near-Death Experience Scale, a questionnaire that scores features associated with these experiences. Seven people remembered something from the period in question; four gave accounts that met the scale’s threshold for a near-death experience. The Southampton study.

This illustrates why it helps to ask both whether a person remembers anything and what they remember. An ordinary recollection and an account of leaving the body are different findings. Using a common questionnaire gives researchers a consistent way to classify accounts, although any classification also shapes what is included.

The study was small, with only four qualifying accounts. Its contribution was to show how the question could be investigated systematically in a hospital. This approach is called prospective research: the researchers plan the investigation and follow patients as events occur, then interview survivors, rather than recruit only people already known to have an unusual story.

AWARE: could an account be checked against events in the room?

The larger AWARE study—short for AWAreness during REsuscitation—used hidden pictures to test reports of out-of-body perception. Pictures were placed on shelves facing upwards, where patients could not see them from their beds. Someone who described viewing the room from above could be asked whether they had seen a picture.

Published in 2014, the study recorded 2,060 cardiac arrests. Of 330 discharge survivors, 101 completed detailed interviews. Nine of those 101 met near-death-experience criteria. Two described seeing or hearing resuscitation events; one account could be checked against medical information.

That patient recalled a machine directing rescuers to deliver a shock and described a staff member involved. Records supported those details. The researchers inferred about three minutes of awareness from the defibrillator’s operating sequence. They had no recording of his brain activity to establish what his brain was doing then.

Both patients who described treatment events were resuscitated in rooms without the picture shelves. The study therefore obtained a corroborated account of treatment, but no successful identification of a hidden picture. How the patient acquired the information remained unresolved. The AWARE study.

AWARE II: introducing sounds and measuring the brain

The follow-up study, AWARE II, used portable equipment that researchers could bring to a resuscitation. A tablet displayed an image facing upwards above the patient, continuing the attempt to test reports of seeing from an elevated position. Sensors also estimated oxygen levels in the front of the brain. The aim was to investigate whether reported awareness might be related to how effectively blood and oxygen reached the brain during CPR. The study’s research summary.

Headphones provided a separate test: a recording repeated three fruit names—apple, pear and banana—during CPR. Afterwards, survivors were asked about their memories and asked to name three fruits. The researchers wanted to distinguish remembering that one had heard the words from choosing the same words without remembering the recording. That second possibility is called implicit learning: earlier exposure influences a later response without conscious recollection.

The results, published in 2023, covered 567 cardiac arrests across 25 hospitals. Fifty-three patients survived; 28 were interviewed. Eleven described memories or perceptions, including six whose accounts the researchers classified as recalled experiences of death. No one identified the experimental image. One named the three correct fruits, but did not remember hearing them. The study also examined accounts from a separate group of 126 community survivors; those people were not additional patients monitored during the hospital study. The AWARE II study.

To treat matching fruit names as evidence that the recording influenced memory, researchers would need to show that guessing was an unlikely explanation. As critics pointed out, familiar fruit names can be chosen without having heard a recording. They also emphasised a wider difficulty: an experience remembered after recovery may have occurred before unconsciousness, during treatment or as the person recovered. The interview alone cannot settle its timing. Martial and colleagues on the study’s methods.

Why the brain recordings attracted attention

Alongside the memory tests, AWARE II used electroencephalography, or EEG. Sensors on the scalp detect electrical activity produced by the brain. The recorded signals contain rhythms that researchers describe using names such as alpha, theta and delta. These names describe how quickly the signals fluctuate: alpha is faster than theta and delta. They do not identify a particular thought, memory or vision. An introduction to EEG.

Researchers obtained interpretable EEG recordings from 53 patients. Some recordings showed organised rhythms during CPR, even though the patients showed no outward signs of awareness. This attracted interest because it suggested that the brain’s electrical activity during resuscitation could be more complex than a simple, continuous shutdown. Greyson and van Lommel’s discussion of the EEG findings.

However, the recordings and the remembered experiences could not be matched in the way needed to explain an individual account. Only two of the 28 interviewed survivors had EEG data, and neither reported remembering an experience. The researchers therefore could not show which brain pattern accompanied a particular life review or out-of-body experience. Recordings from one patient cannot establish what another patient’s brain was doing.

That distinction is easy to lose when the findings are compressed into a headline. Detecting brain activity during CPR and hearing a survivor’s extraordinary recollection are both observations worth investigating. Establishing a relationship between them requires recordings and recollections from the same person, with a reliable way to connect their timing.

A more controlled setting: the 2025 surgical study

Emergency resuscitation is a difficult setting for research. Staff must prioritise treatment, equipment cannot always be attached in time, and many patients do not survive to be interviewed. A planned operation offers an opportunity to prepare measurements in advance.

In 2025, Joshua Ross, Parnia and colleagues reported a study of 36 patients undergoing operations involving deep hypothermic circulatory arrest. In these procedures, cooling reduces the body’s oxygen requirements so circulation can be temporarily stopped for surgery. This was a feasibility study: its main purpose was to find out whether the proposed research methods could be used successfully.

During the planned pause in circulation, a tablet displayed pictures and headphones played a recording naming three fruits. Thirty-five patients were later interviewed about their memories and the experimental material. No one remembered seeing the pictures or hearing the fruit names. Three nevertheless named the correct fruits when asked to guess. The authors acknowledged that chance could explain those answers.

Three patients recalled other experiences around the operation, including one possible recalled experience of death. Useful EEG recordings were obtained for nine patients, but none belonged to those three. The study showed that these tests could be attempted during planned surgery, while also revealing how much technical improvement was needed to connect a remembered experience with a brain recording. The 2025 surgical feasibility study.

What the 2026 analysis adds

A paper published in 2026, led by Elise Huppert with Parnia among its authors, took a closer look at the physiological question: how do electrical activity and oxygen supply relate to recovery of the heartbeat during CPR? It was an additional analysis of hospital monitoring data, not a separate replication of the survivor-interview findings.

Alpha rhythms were observed as late as 35 minutes into CPR, while slower theta or delta rhythms appeared as late as 60 minutes. Patients showing alpha activity were more likely to regain an effective heartbeat, although the small sample limited conclusions about who ultimately survived. Huppert and colleagues, 2026.

The finding matters for efforts to protect and restore brain function. Electrical activity can reappear during prolonged resuscitation under suitable conditions. It does not follow that a patient was continuously conscious for an hour. CPR was taking place throughout the relevant period, and an EEG rhythm by itself cannot tell us whether someone was experiencing a life review, hearing a voice or having no reportable experience.

How Parnia interprets the findings

Parnia is particularly interested in the apparent clarity and coherence of some accounts. People can describe an organised, meaningful experience associated with a period of profound physical crisis. He proposes that one explanation may involve disinhibition—the weakening of the brain’s usual restraints on its own activity.

In his account, changes near death may allow access to memories and aspects of awareness that are ordinarily unavailable. This could help explain why some people describe an unusually comprehensive review of their lives. It remains a hypothesis: the studies have not traced that proposed process in an individual while they were having and later remembering such an experience. Parnia’s interpretation, described by NYU Langone.

His book Lucid Dying, published in 2024, develops his broader view of what resuscitation science and these accounts might mean for our understanding of life and death. Readers interested in his perspective can explore it alongside the research papers, which provide the methods and results behind particular claims. About Lucid Dying.

The debate continues. In a 2026 letter, Parnia and colleagues called for empirical research into recalled experiences of death without prejudice. Such a letter contributes an argument to a scientific discussion; it does not add a new group of experimental results. Parnia and colleagues’ 2026 letter.

How much can these studies establish?

The work documents that some survivors report detailed experiences associated with cardiac arrest and treatment. It also shows how hard it is to establish their precise timing and explain how they occurred. Most people enrolled after a cardiac arrest cannot ultimately contribute an interview. Consequently, the frequency of reports among interviewed survivors cannot simply be applied to everyone whose heart stops.

Questions about an afterlife require a further evidential step. A convincing demonstration of perception independent of the brain would need to exclude explanations involving remaining or recovering brain function, ordinary hearing, chance and memories formed at another time. The studies described here have not achieved that. Nor does merely labelling an account a hallucination provide a detailed explanation of it.

It helps to distinguish the experience, its cause and its meaning. A person may remember profound peace and subsequently live differently. That can be an important fact about their life while the biological explanation remains uncertain. Taking the account seriously and examining its interpretation carefully are compatible activities.

Why these accounts matter to the Metaphor Society

Descriptions of leaving the body, travelling towards light, crossing a boundary and returning home have a particular interest for anyone studying metaphor. They give experience a shape through movement, direction and place. A person describing “home”, for example, may be communicating a sense of recognition and belonging that a list of emotions would struggle to convey.

This is a way of examining the accounts, rather than a finding from Parnia’s experiments. It does not require us to decide in advance that an experience is merely figurative. Instead, we can ask what the person means by their words. Does “returning” suggest relief, disappointment, responsibility or a changed relationship with ordinary life? What does a life review communicate about how the person now understands their relationships?

The same care applies to scientific language. Saying that the brain “switches off” invites us to imagine a single switch with two positions. Actual resuscitation involves changing circulation, oxygen supply and electrical activity. The metaphor may be convenient, but it can obscure the very processes researchers are trying to measure.

The patient beyond the experiment

Parnia’s wider programme asks how people live after cardiac arrest, including its effects on memory and psychological wellbeing. It also investigates children’s experiences after critical illness and episodes in which people with severe dementia unexpectedly regain a degree of mental clarity. These are separate clinical questions, connected by an interest in the relationship between observable brain impairment and a person’s capacity for experience. The laboratory’s patient research.

Alongside this work are efforts to improve CPR and prevent brain injury. For a resuscitation researcher, bringing back an effective heartbeat is only part of the task; the person’s subsequent recovery also matters. The laboratory’s resuscitation research.

Parnia has helped turn remarkable personal accounts into questions that can be investigated in hospitals. The methods remain difficult and the interpretations contested. What makes the work valuable is the effort to connect careful listening with observations that can be checked, while retaining an interest in the person whose experience prompted the investigation.

Selected primary papers

• Parnia et al. (2001): the Southampton prospective study.
• Parnia et al. (2014): AWARE.
• Parnia et al. (2022): the proposed framework for recalled experiences of death.
• Parnia et al. (2023): AWARE II.
• Greyson and van Lommel (2024): discussion of EEG and reported experiences; Martial et al. (2024): questions about the methods.
• Ross et al. (2025): research during planned circulatory arrest.
• Huppert et al. (2026): brain electrical activity during prolonged CPR.
• Parnia et al. (2026): a call for empirical research.