The moment of death is a mystery. One thing is certain: Shortly before death, the senses gradually disappear. More is now known about which fail first.
What happens in the last hours and minutes before death? This riddle has captivated mankind since the beginning of time – and with the help of research, at least parts of it can be gradually revealed.
For most of the history of the human species, dying has been a rather short and rapid process. However, modern medicine now makes it possible in many cases for seriously ill patients to die gradually rather than suddenly. This also allows doctors and scientists to examine the dying process more closely.
In the meantime, physicians have also found out which sense the dying first lose in the hours before their death.
The German Society for Palliative Medicine lists the following as typical externally perceptible physical signs of impending death:
- Increased tiredness and lethargy
- Longer sleep phases up to coma
- Reducing food and fluid intake
- Reduction in urine output
- Cold feet, arms, hands (poor circulation) or excessive sweating
- Dark, livid discoloration of the underside, hands, knees, and/or feet (marbling)
- Pale “waxy” skin
- Pronounced mouth-nose triangle
- Weak pulse and drop in blood pressure
- Altered breathing rhythm (Cheyne-Stoke breathing)
- Reduced perception of the outside world (time, space, people)
Hearing and touch finally fail
Exactly how the dying person’s perception of the outside world changes has been widely reported by people who have had near-death experiences or by family members and staff who have witnessed the death of another person.
According to James Hallenbeck, a palliative care physician at Stanford University, people tend to lose their senses and needs in a specific order. In Palliative Care Perspectives, his guide to palliative care for physicians, Hallenbeck writes, “First hunger is lost, then thirst.” Next fail speech, followed by sight. Finally, according to the doctor, hearing and touch are usually lost.
David Hovda, director of the UCLA Brain Injury Research Center, a research facility in Los Angeles, USA, explained this sequence in the US magazine “The Atlantic” as follows: The brain starts a process in which areas that are necessary for survival would be sacrificed are less important.
The Glistening Tunnel: What’s behind it?
Hovda has a theory for the perception of a brightly lit tunnel in some near-death patients: “When the brain starts to change and die, different parts get excited, and one of the parts that gets excited is the visual system.” This is the moment when the dying begin to see light, says the researcher.
Jimo Borjigin, a neuroscientist and professor of molecular and integrative physiology at the University of Michigan, also reports that many cardiac arrest survivors shared amazing experiences while unconscious: “They see lights and describe the experience as more real than real,” Borjigin said.
The researcher has firmly established that just before death in animals, the levels of certain neurochemicals in the brain suddenly increase and suggests that this could also contribute to the apparently hallucinogenic responses in humans.
Activity in the brain increases just before death
Among other things, Borjigin and her research team conducted an experiment on rats whose hearts they stopped after being anaesthetized. “Suddenly all different regions of the brain were synchronized,” reported Borjigin. The brains of the animals showed higher performance in different frequency waves and the electrical activity of different brain regions working together increased.
If you concentrate, for example try to understand a word or remember a face, this is more noticeable, says Borjigin. “These parameters are commonly used when studying human consciousness in awake people. So we thought that if you’re awake or aroused, similar parameters should also increase in the dying brain. The researchers found that this was indeed the case.
