Although death is a biological process, the last moments of life may include experiences which are much more mysterious than the physical changes taking place in the body. Those people who are approaching death or who survive a cardiac arrest have at times given accounts of vivid visions, unusual sensations, alterations in their sense of time, and even the sensation of leaving their bodies.Scientists are able to account for some of these experiences on the basis of changes that take place in the brain, but with others it is still difficult to understand them completely.The process of dying generally starts before the heart has ceased to beat altogether. As the circulation grows weaker, less blood and oxygen get to various parts of the body, and the hands, feet, arms and legs may turn cold while the skin becomes blotchy with reddish or purple patches, a condition known as mottling.A person might also start sleeping for much longer periods and become increasingly hard to get through to. Confusion may set in since the blood flow and chemical activity in the brain change, leading the person to lose an awareness of time, forget where they are, or not recognize people who they usually know.As the body slowly loses the ability or the need to keep up normal activity, both eating and drinking tend to decrease. When the body is nearing the end of life, more energy is directed towards essential functions.Among the most interesting changes might happen within the mind.People who have survived cardiac arrest have given accounts of experiences which are remarkably similar. Among these descriptions are a strong sense of peace, freedom from pain, or the feeling of drifting away from their physical body.Some people have said that they saw brilliant lights, strange figures they had never seen before, their deceased relatives, or have had the odd feeling that time was moving either very quickly or very slowly. Moreover, a number of the survivors have stated that they were able to see what was going on around them during the resuscitation, occasionally describing this as if they had been watching the scene from above.They are usually known as near-death experiences and have caused a great deal of debate since they seem extremely real to the individuals who have them.Yet the researchers have not been able to prove that these experiences demonstrate the existence of an afterlife; it is possible that variations in oxygen levels, brain chemistry, electrical activity, and extreme physical stress all play a role in causing unusual perceptions during the period around cardiac arrest.The brain might also generate strong experiences when a person is nearing natural death. There are cases in which individuals who are dying say that they see bright lights or people who have already died. It has been suggested by researchers that these visions may be the brain’s reaction to significant physiological changes rather than proof that the person is actually witnessing another world.Scientists have also looked into another phenomenon which involves Tibetan Buddhist monks.The technique called tukdam consists of achieving a deep state of meditation just at the time of dying. There have been instances where monks seemed to stay remarkably well preserved for a period following their death, the visible process of decomposition being delayed in comparison to what is normally to be expected.The scientists who are looking at these cases want to find out what they might tell us about the connection between meditation, consciousness, and the biological processes that occur after death; the phenomenon is still not well understood and therefore needs more scientific investigation.Even though science is able to describe a great many of the physical events that take place when the body shuts down, it has not yet been able to give answers to all the questions regarding the experience of dying.It is known that the brain is capable of producing remarkable sensations when under extreme conditions, and it is still one of the fundamental questions without an answer whether these experiences are entirely the result of brain activity or indicate something that lies beyond our present understanding regarding death.Every human being ultimately comes to this biological limit. Although we are learning more and more about what occurs to the body, the state of consciousness in the last moments is still a mystery.