Loss of Consciousness and Near-Death Experiences
James E. Whinnery, Ph.D., M.D.
History and scientific research efforts are replete with inquiry into the secrets of death, the dying process, and what, if anything, happens to consciousness following bodily death. Our scientific understanding of the psychophysiologic aspects of these processes, however, remains relatively limited. In spite of the recurrent psychophysiologic findings reported from these studies, little emphasis has been placed on the common physiologic event that occurs � loss of consciousness. The results of loss and recovery of consciousness experiments in completely healthy humans may provide insight into the normal neurologic processes that occur in association with NDEs and other related phenomenon.
This report focuses on the psychophysiologic events associated with acceleration (+Gz)-induced loss of consciousness (G-LOC) in completely healthy individuals. Acceleration (+Gz, head-to-foot) stress is a unique aspect of flying fighter aircraft during aerial combat maneuvering. Modern fighter aircraft can rapidly achieve (<1 second) and sustain (> 5 seconds) levels of +9Gz, which places most humans at risk for G-LOC. The magnitude of such stress can perhaps be understood by realizing that a 200 pound man at +1Gz (the everyday gravitational stress experienced by earth-bound humans) can be transformed in one second or less at +9Gz to an 1800 pound man in a fighter aircraft.
The +Gz-stress reduces blood flow to the head and causes pooling of blood in the abdomen and extremities. Cephalic nervous system ischemia results in G-LOC. A solution for the G-LOC problem requires a thorough understanding of the alterations of consciousness. Although preventing further losses of aircrew and aircraft is the goal of fighter aviation medicine, the results from experiments involving loss-of-consciousness in completely healthy humans should be of interest to a broad range of scientific disciplines.
The results to be discussed represent data collected from over 15 years of acceleration-research experience and more than 700 episodes of G-LOC that occurred in fighter aircraft and during human-centrifuge +Gz-exposure. The individuals included experimental research subjects, fighter aircrew, and students in various aviation medical courses. The average age of the individuals was approximately 32 years. All were healthy and asymptomatic, having successfully completed military-flying physical examinations. The centrifuge G-LOC episodes were all recorded on videotape for subsequent analysis.
The sequence of events for a typical G-LOC episode is shown schematically in Figure 1. When rapid-onset +Gz-stress is applied to a sustained level well above tolerance, there is an approximate 6-second period (functional buffer period) during which normal neurologic function persists, despite loss of adequate blood flow. At the end of this period, consciousness is lost, and the +Gz-stress is reduced back to ground-level conditions. The length of the unconsciousness episodes averaged 12 +/- 5(S.D.) seconds, with a range of 2 to 38 seconds. The estimated average length of time blood flow to the central nervous system was altered during the loss and recovery of consciousness was approximately 15 to 20 seconds.
Myoclonic convulsive activity was observed in association with 70 percent of the G-LOC episodes. The myoclonic activity began on the average 7.7 seconds after the onset of unconsciousness and lasted 3.9 seconds. The myoclonic activity was observed to stop coincident with the return of consciousness. Upon recovery of consciousness, there is a period of relative incapacitation that lasts on the average about 12 seconds, in which there exists confusion/disorientation. The end of this period is measured by the return of the ability to make purposeful movement (that is, regaining aircraft control or performing other specific tasks). Individuals who lost consciousness were interviewed in the centrifuge on videotape immediately following the G-LOC episode.
It is possible to classify the G-LOC episodes according to the diagram shown in Figure 2. The G-LOC experience includes specific visual symptoms (tunnel vision through blackout), myoclonic convulsive activity, memory alterations, dreamlets, and other psychologic symptoms. The major, overall G-LOC experience characteristics that have commonality with NDEs are shown in the following table.
|1. Tunnel vision/bright light
||10. Psychologic state alteration
|3. Automatic movement
||11. Friends/family inclusion
||12. Prior memories/thoughts inclusion
|5. Out-of-body experience
||13. Very memorable (when remembered)
|6. Not wanting to be disturbed
||15. Strong urge to understand
|8. Vivid dreamlets/beautiful places
Ischemically induced loss-of-consciousness is usually considered a hazardous exposure in healthy humans. This research was conducted with the risk-benefit ratio balanced by the continuing operational loss of aircrew and aircraft. The G-LOC syndrome, however, suggests that loss of consciousness may be considered to be an evolutionarily developed protective mechanism that is evoked in a stepwise sequence in the face of excessive +Gz-stress (gravity), well before any pathologic alterations of the nervous system occurs. Specific neurologic states of consciousness, subconsciousness, and unconsciousness are induced during loss and recovery of consciousness as the major source of energy (blood flow) is altered by +Gz-stress. Each of these neurologic states (consciousness, subconsciousness, unconsciousness) represents a range of neurologic energy distributed over a specific nervous-system structure. They become evident from the G-LOC syndrome symptoms that can be observed. When considering G-LOC from a thermodynamic perspective, it is necessary to define at least one additional neurologic state, a state that corresponds to a critical (very low) range of reduced energy. From this state, by definition, it is not possible to regain a neurologic state above unconsciousness because of pathologic alterations of the nervous system. This neurologic state is death. The magnitude and duration of the +G-induced ischemia (energy reduction) of the cephalic nervous system determines just how "near" to the neurologic state of death the individual comes.
Altered neurologic-states, whether resulting from G-LOC or the NDE, can produce vivid experiences to those who have them. Some differences between G-LOC and the NDE would be expected, if for no other reasons than the circumstances that cause them and the magnitude of the insults to the nervous system, which are different. The G-LOC syndrome symptoms are the normal responses of completely healthy individuals to relatively minimal periods of cephalic nervous system ischemia. If there are unique characteristics associated with the NDE, then their isolation would appear to be facilitated by focusing on what the real differences are in the individuals, their physical states, the environmental situation, the type of insult, and the symptomology between G-LOC and the NDE.
The psychophysiologic events of the NDE may be at least partially open to experimental investigation in healthy humans and not solely upon clinical happenstance. The need to understand the neurologic states of consciousness, subconsciousness, and unconsciousness, along with the mechanisms that cause the transition between these neurologic states is shared by those investigating NDEs and G-LOC. There are several types of alterations, both physiologic and pathologic, that can disturb the normal state of consciousness. Based on the physiologic insult similarity, it is possible to establish a framework, as shown in Figure 3, for the systematic study of the NDE and for relating NDE research to other psychophysiologic research.
Loss-of-consciousness episodes of all types appear to have an explainable physiologic basis. They are, therefore, open for scientific investigation. At least the loss-of-consciousness aspect of the NDE, therefore, has a potentially explainable and experimentally explorable basis. It would be odd if the symptoms associated with loss and recovery of consciousness were not part of the NDE. The fact that many of the NDE symptoms are very similar to those resulting from loss and recovery of consciousness suggests that individuals who report their NDEs have provided accurate symptom descriptions. This includes those symptoms beyond the scope of G-LOC experimentation, which are unique to the NDE.
J.E. Whinnery, Ph.D., M.D.
Department of Chemistry
West Texas A&M University
Canyon, Texas 79019-0001
NOTE: For a more in-depth discussion of this research, see "Psychophysiologic Correlates of Unconsciousness and Near-Death Experiences" by Dr. James E. Whinnery, Journal of Near-Death Studies, Vol. 15, No. 4, Summer 1997.
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