Angela Morrow, RN, BSN, CHPN, is a certified hospice and palliative care nurse. She wrote;
When a person knows they are dying, they have the opportunity to do five important things:
1. Apologize for past mistakes
2. Forgive others for their mistakes
3. Thank those people who matter most
4. Say "I love you" to those they love
5. Say goodbye
Without the opportunity to do these valuable things, your loved one could die with unfinished business.

It makes me think of the song by Mike and the Mechanics “The living years” which is a good song .

In my experience - yes they do know or at least my husband did and he did all of these things to prepare for his death.

Human brain may stay active for hours after death
The team of scientists from New York’s Stony Brook University of Medicine, looked at patients with cardiac arrests in Europe and the US. They noted that those of the patients who were successfully resuscitated after their heart had stopped beating could recall the conversations around them between the healthcare personnel and were aware of their surroundings.
Study leader Dr. Sam Parnia said that the patients could describe in details what happened around them. He explained that the time death is declared is the one when the heart stops beating. As the heart stops beating, it stops pumping blood to the brain and slowly the brain begins to shut down, he explains. He added that this process of the brain shutting down slowly may take hours and the person may be dead during this time but aware of their surroundings.

The scientists have noticed that some people, at the moment of death or when they came back to life after death, saw very special and strange events that could not be explained by the science of traditional medicine.
In America the psychiatrist Moody has collected the experiences of fifty people after death.
Demons approach a person during his life, but he gets the help of angels, when his soul separates from his body.
Father Seraphim Rose focuses his attention on some of the points that Moody notes. First, “out-of-body experiences.” They are experiences that everyone felt as a state in which the soul leaves the body, yet it does not continue in its consciousness. The soul feels commendable warmth and ease, and it sees the people surrounding the dead body but cannot communicate with them.
Secondly, “meeting with others.” That is, as Modi says, the soul feels lonely for only a short time, and then it feels like it meets others where it suddenly sees, relatives and friends who have died.
The common feature of these post-death experiences is the “entity of light” or the “enlightening entity.” All those who have had such experiences describe the appearance of a light rapidly increasing in brightness. And they all recognized him as a certain personality filled with warmth and love, to whom the recently deceased was attracted by a kind of magnetic attraction. Some of them insisted that this figure is Jesus , and others insisted that he is an angel.
My note:
The dying person sees the angel of death and knows him, so he knows that he will die

Father Seraphim provides personal testimony:
‘’It is from the illness of my spiritual father, Archbishop Kallinikos, Archbishop of Edessa. After he underwent surgery to remove a brain tumor he fell into a deep coma. Doctors said that he was on the verge between life and death. When he regained consciousness a few days later, he spoke with heavy tears. He saw his soul outside his body, and he was seeing all of us preparing for the funeral. He pointed to a specific nurse who used to write down his measurements to buy him the shroud. He said that at that hour he was reciting the prayer of separating the dead to himself.’’
Orthodox point of view
‘’We do not have the right to dismiss all experiences just because they are beyond our assumptions. Nor should we act like atheists who think that the soul is a simple energy for the body and perishes with it.
In Evergitinos there are examples that clearly indicate a state after death. Including about Boutros the monk who “got sick and died.” Then he saw all the torments of hell and places of fire. Then his soul was returned to his body. He declared everything he saw and lived in repentance.’’

In 1998, a website called the Near Death Experience Research Foundation (NDERF, nderf.org) was established to conduct NDE research and to be a public service.
Portions of the NDERF website, including the NDE questionnaire, have been posted in over 20 different languages.
This prominence of the NDERF website provided a unique opportunity to conduct a large-scale study of NDEs, including NDEs from around the world. At the current time there are over 3,700 NDEs posted on the NDERF website, which is by far the largest collection of publicly accessible NDE accounts in the world.

A 2020 study that investigated hearing in palliative care patients who were close to death provides evidence that some people may still be able to hear while in an unresponsive state. Electroencephalography (EEG) was used to measure the dying brain's response to sound. The findings suggest that telling a person you love them in their final moments may register with them.

The view of earthly religions (non-heavenly) about death;
In the Pharaonic civilization, they believed in resurrection after death, and that mummification was essential for safe passage from the world of the living to the afterlife.
The Hindu holy book (200-500 B.C.), makes death in the grip of the god “Shiva,” the god of solution and annihilation. They cremate the dead and his family takes the ashes of his body and scatters it in the holy river. Sikhs do the same in that ritual.
In the Zoroastrian religion (444 B.C.), death is the work of Satan, so they leave the dead naked on the roof of a tower. The birds of prey eat it and bones remain, in a hole that the sun purifies them from the defilement of sin, so that bliss enters.
The Greeks and Romans cremated their dead. Lucretius, the first BC Roman philosopher, said in the poem “The Nature of the Universe” that “death is not annihilation, but rather the severing of connections and linking them into new groups.” This view was expressed by the Roman philosopher, Lucius (4 BC), when he said: “A person may lose his life at any time, but not existence.”
In the Buddhist religion, they leave the corpses on top of a mountain. A specialized man cuts them to be eaten by animals and birds, leaving the bones. Then the man beats them with a hammer and mixes them with flour, butter, milk and sugar, and leaves them for the vultures to eat. They believe in reincarnation, which means that the soul of the dead person is transferred to the body of another human being, animal or plant.
Denying death or fleeing from it
Hedonists deny death. They see it as not a natural part of the life cycle, but rather an external enemy, which must be fought by satisfying the desires of the soul, whatever the consequences.
The ancient alchemists in Europe went through a long experiment to discover the “elixir of immortality”. When Ponce discovered Florida in 1513, he had been searching for more than three years for a "fountain of youth" that would "rejuvenate all who drink from it."
The Spanish Saint Teresa said 500 years ago: “Remember that you have one soul, one death, one life… When you realize that, you will know that you have neglected many things in your life.”

The first prospective study of the accuracy of out-of-body observations during near-death experiences was by Dr. Michael Sabom. This study investigated a group of patients who had cardiac arrests with NDEs that included OBEs, and compared them with a control group of patients who experienced cardiac crises but did not have NDEs. Both groups of patients were asked to describe their own resuscitation as best they could. Sabom found that the group of NDE patients were much more accurate than the control group in describing their own resuscitations.
Another prospective study of out-of-body observations during near-death experiences with similar methodology to Sabom’s study was published by Dr. Penny Sartori. This study also found that near-death experiencers were often remarkably accurate in describing details of their own resuscitations. The control group that did not have NDEs was highly inaccurate and often could only guess at what occurred during their resuscitations.

Human bodies can move on their own after death, study finds
Researchers studying the process of decomposition in a body after death from natural causes found that, without any external “assistance,” human remains can change their position. This discovery has important implications for forensic science
Often, forensic scientists will assume that the position in which they find a dead body is the one that the person was in at the time of death — unless, that is, there is evidence that external factors, such as scavengers or a perpetrator, may have altered it.
However, new research led by Alyson Wilson — from Central Queensland University in Rockhampton, Australia — now suggests that human bodies can actually be somewhat restless after death.
This discovery — which Wilson and colleagues have not yet reported in a paper they have published — is linked to a larger project, concerning the use of time-lapse imaging techniques to estimate the time since death. This latter project’s findings appear in Forensic Science International: Synergy.
For the research, the investigators had access to a donated human body — “a mature male who died of natural causes.”
The researchers recorded the body’s full decomposition within the premises of the Australian Facility for Taphonomic Experimental Research (AFTER), the only body farm in Australia.
Researchers use such facilities to investigate how human bodies decompose — or remain preserved — under different conditions.
The findings from research projects such as the current one often help forensic scientists develop more accurate ways of determining essential information — including time or place of death — at a crime scene.
Bodies keep on shifting as they decompose
In this research, the investigators were able to make sure that scavenging animals that might feed on decaying flesh could not reach the body, and thus alter its position.
The team took photos of the decomposition process of the body over more than 17 months and found that the remains appeared to move on their own.
For instance, while they initially placed the arms alongside the body, at one point, the researchers note, the arms shifted and were flung to one side.
“We think the movements relate to the process of decomposition, as the body mummifies and the ligaments dry out,” explains Wilson in an interview for the Agence France-Presse.
Wilson and colleagues believe that understanding when such shifts are likely to occur during the process of decomposition could help forensic scientists provide more accurate estimates of the time of death.
It could also, the researchers add, help reduce the possibility that forensic investigators will make incorrect deductions about crime scenes.
“They’ll map a crime scene, they’ll map the victim’s body position, they’ll map any physical evidence which is found, and they can understand the cause of death,” says Wilson.
The researcher believes this may well be the first time that someone has attempted to match natural alterations in a body’s position after death with different stages of the process of decomposition.

https://www.medicalnewstoday.com/articles/326281

Two large retrospective studies investigated the accuracy of out-of-body observations during near-death experiences. The first was by Dr. Janice Holden. Dr. Holden reviewed NDEs with OBEs in all previously published scholarly articles and books, and found 89 case reports. Of the case reports reviewed, 92% were considered to be completely accurate with no inaccuracy whatsoever when the OBE observations were later investigated.
Another large retrospective investigation of near-death experiences that included out-of-body observations was recently published. This study was a review of 617 NDEs that were sequentially shared on the NDERF website. Of these NDEs, there were 287 NDEs that had OBEs with sufficient information to allow objective determination of the reality of their descriptions of their observations during the OBEs. Review of the 287 OBEs found that 280 (97.6%) of the OBE descriptions were entirely realistic and lacked any content that seemed unreal. In this group of 287 NDErs with OBEs, there were 65 (23%) who personally investigated the accuracy of their own OBE observations after recovering from their life-threatening event. Based on these later investigations, none of these 65 OBErs found any inaccuracy in their own OBE observations.

Near-death experiences with vision in the blind and supernormal vision
There have been a few case reports of near-death experiences in the blind. The largest study of this was by Dr. Kenneth Ring. This Investigation included 31 blind or substantially visually impaired individuals who had NDEs or out-of-body experiences. Of the 31 individuals in the study, 10 were not facing life-threatening events at the time of their experiences, and thus their experiences were not NDEs. There were 14 individuals who were blind from birth in this study, and nine of them described vision during their experiences. This investigation presented case reports of those born totally blind that described in NDEs that were highly visual with content consistent with typical NDEs.
The NDERF website has received additional case reports of near-death experiences among those legally blind. For illustration, the following NDE happened to Marta, a five-year-old blind girl who walked into a lake:
“I slowly breathed in the water and became unconscious. A beautiful lady dressed in bright white light pulled me out. The lady looked into my eyes asked me what I wanted. I was unable to think of anything until it occurred to me to travel around the lake. As I did so, I saw detail that I would not have seen in “real” life. I could go anywhere, even to the tops of trees, simply by my intending to go there. I was legally blind. For the first time I was able to see leaves on trees, bird’s feathers, bird’s eyes, details on telephone poles and what was in people’s back yards. I was seeing far better than 20/20 vision.

God said; ‘And when the agony of death comes in truth (they will say): 'This is what you (man) have been trying to avoid! ' Each soul shall come with a driver, and a witness. (2 angels ). (It will be said): 'Of this you have been heedless. Therefore, we have now removed your covering. Today your sight is sharp.'
Commentators said:
Normal human vision works within a specific range of vision. For example, the eye does not see in the dark. Nor can see angels.
The verse says that at death, normal eyesight ceases to function, and stronger eyesight begins to work, perhaps for a few last seconds, when a person sees God’s creatures that are hidden from him, such as angels and others. This is because the soul lives according to certain laws of which we are not aware, after death.
Quran; ‘They question you about the spirit (soul). Say: 'The spirit is from the command of my Lord. Except for a little knowledge you have been given nothing.’

Near-death experiences and life reviews
Some near-death experiences include a review of part or all of their prior lives. This NDE element is called a life review. NDErs typically describe their life review from a third-person perspective. The life review may include awareness of what others were feeling and thinking at the time earlier in their life when they interacted with them. This previously unknown awareness of what other people were feeling or thinking when they interacted with them is often surprising and unexpected to the NDErs. Here is an example of a life review: “
I went into a dark place with nothing around me, but I wasn’t scared. It was really peaceful there. I then began to see my whole life unfolding before me like a film projected on a screen, from babyhood to adult life. It was so real! I was looking at myself, but better than a 3-D movie as I was also capable of sensing the feelings of the persons I had interacted with through the years. I could feel the good and bad emotions I made them go through.”
In my review of 617 near-death experiences from NDERF, a life review occurred in 88 NDEs (14%). None of the life reviews in these NDEs appeared to have any unrealistic content as determined by my review or based on comments by the NDErs about their own life reviews. Life reviews may include long forgotten details of their earlier life that the NDErs later confirm really happened. If NDEs were unreal experiences, it would be expected that there would be significant error in life reviews and possibly hallucinatory features. The consistent accuracy of life reviews, including the awareness of long-forgotten events and awareness of the thoughts and feelings of others from past interactions, further suggests the reality of NDEs.

Near-death experiences of young children
Investigation of near-death experiences in very young children is important because at an early age they are less likely to have established religious beliefs, cultural understandings about death, or even an awareness of what death is. Very young children would be very unlikely to have heard about near-death experiences or understand them. I investigated the NDEs in children age five and younger in the same group of 613 NDErs previously discussed in the section on NDEs while under general anesthesia. Two NDEs were excluded as they did not provide their age in the survey. The study groups included 26 NDErs that were age 5 and younger (average 3.6 years old) and 585 NDErs age 6 and older at the time of their NDEs. The NDERF survey included 33 questions about the content of their NDEs. Statistic was used to compare the responses to these 33 questions between the two groups. There was no statistically significant difference to the responses between the two groups to any of the 33 questions. The NDERF study found that the content of NDEs in children age five and younger appeared to be the same as the content of NDEs in older children and adults. The finding of the NDERF study are corroborated by the investigation of Dr. Cherie Sutherland who reviewed thirty years of scholarly literature regarding the NDEs of children and concluded:
“It has often been supposed that the NDEs of very young children will have a content limited to their vocabulary. However, it is now clear that the age of children at the time of their NDE does not in any way determine its complexity. Even prelinguistic children have later reported quite complex experiences…. Age does not seem in any way to affect the content of the NDE.”
Very young children have near-death experience content that is strikingly similar to older children and adults. This is further evidence that NDEs are occurring independently of preexisting cultural beliefs, religious training, or awareness of the existence of NDE.

Encountering deceased loved ones in near-death experiences
Near-death experiences may describe encounters with people that they knew during their earthly life. The following is an example of encountering a deceased loved ones in an NDE. This example is also notable as the NDEr was born totally deaf:
“I approached the boundary. No explanation was necessary for me to understand, at the age of ten, that once I cross[ed] the boundary, I could never come back— period. I was more than thrilled to cross. I intended to cross, but my ancestors over another boundary caught my attention. They were talking in telepathy, which caught my attention. I was born profoundly deaf and had all hearing family members, all of which knew sign language! I could read or communicate with about twenty ancestors of mine and others through telepathic methods. It overwhelmed me. I could not believe how many people I could telepathize with simultaneously.