Can someone explain this shyt to me, why you pass out, I have been looking all over the internet for answers.
From Wikipedia:
Self-induced hypocapnia
The second mechanism requires
hyperventilation (forced overbreathing) until symptoms of
hypocapnia such as tingling, light-headedness or dizziness are felt, followed by a breath-hold. This alone is enough to cause a blackout, but it is widely believed that the effect is enhanced if lung air pressure is increased by holding the breath "hard" or "bearing down" (tightening the diaphragm as in a forced exhalation while allowing no air to escape or having an assistant apply a bear-hug).
[9] These latter actions may augment the effects of hypoxia by approximating the
Valsalva maneuver, causing vagal stimulation.
The hyperventilation leads to an excessive elimination of
carbon dioxide (CO2) whereas no significant additional amounts of oxygen can be stocked in the body. As only carbon dioxide is responsible for the breathing stimulus, after hyperventilation, breath can be held longer until
cerebral hypoxia occurs. The blood also becomes abnormally alkaline as a result of the excessive elimination of carbon dioxide; this subsequent rise in blood
pH is termed
alkalosis. Alkalosis interferes with normal oxygen utilization by the brain. The symptoms of alkalosis are neuromuscular irritability, muscular spasms, tingling and numbness of the extremities and around the mouth, and a dizziness, or giddiness, often interpreted as a sense of
euphoria.
In the body alkalosis generally induces
vasodilatation (widening of the blood vessels) but in the brain alone it causes
vasoconstriction (narrowing of the blood vessels). This vasoconstriction appears to be made even worse by a sudden increase in blood pressure caused by squeezing or holding the breath "hard". The alkalosis-induced euphoria can be followed rapidly by hypoxia-induced unconsciousness. The sequence of events leading to unconsciousness from hyperventilation is as follows[
citation needed]:
- Decrease in partial pressure of alveolar CO2.
- Decrease in partial pressure of arterial CO2.
- Increase in blood pH, (respiratory alkalosis).
- Vasoconstriction of blood vessels supplying brain.
- Pooling of the blood present in the brain at the time.
- Brain rapidly uses up oxygen (O2) available in the pooled blood.
- O2 concentration in the brain drops.
- Unconsciousness from hypoxia of cerebral tissue.
Because the brain cannot store reserves of oxygen and, unlike other organs, has an exceedingly low tolerance of oxygen deprivation, it is highly vulnerable if vasoconstriction is not reversed. Normally, if the brain is hypoxic, autonomous systems in the body divert blood to the brain at the expense of other organs; because the brain is vasoconstricted this mechanism is not available. Vasoconstriction is only reversed by the build-up of carbon dioxide in the blood through suspension of breathing.
In some versions the bear-hug is replaced by pressure on the neck in which case blackout is a hybrid of strangulation and self-induced hypocapnia