Is it possible to kill yourself by holding your breath?
This question is obviously copied from Quora, but I had heard it as a fact that we cannot kill ourselves by holding our breath and I'm looking for a referenced answer.
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asked Jun 4, 2018 at 9:19
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$\begingroup$ NAA, since it relies on something other than breath-holding.. but you could kill yourself if you do the over-pressure+hold breath trick to make yourself pass out and happen to hit your head badly when you land. $\endgroup$– JeutnargCommented Jun 4, 2018 at 13:58
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$\begingroup$ Or fall into water face-down, for a less gruesome death. $\endgroup$– JohnEyeCommented Jun 4, 2018 at 14:54
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$\begingroup$ How do you know that we can't? $\endgroup$– pogibasCommented Jun 4, 2018 at 18:38
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2$\begingroup$ @SEwontLetMeDeleteProfile Because, even if we do it long enough to pass out (which is difficult except for under specific circumstances), we will immediately start breathing again. $\endgroup$– forestCommented Jun 5, 2018 at 4:16
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$\begingroup$ The question "why" is ambiguous. Answer "because we evolved this way" is equally good but likely not what you're looking for. $\endgroup$– Agent_LCommented Jun 6, 2018 at 14:33
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2 Answers
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Short answer
Healthy people cannot hold their breaths until unconsciousness sets in, let alone commit suicide.
Background
According to Parkes (2005), a normal person cannot even hold their breath to unconsciousness, let alone death. Parkes says:
Breath‐holding is a voluntary act, but normal subjects appear unable to breath‐hold to unconsciousness. A powerful involuntary mechanism normally overrides voluntary breath‐holding and causes the breath that defines the breakpoint.
Parkes explains that voluntary breath‐holding does not stop the central respiratory rhythm. Instead, breath holding merely suppresses its expression by voluntarily holding the chest at a certain volume. At the time of writing, no simple explanation for the break point existed. It is known to be caused by partial pressures of blood gases activating the carotid arterial chemoreceptors. They are peripheral sensory neurons that detect changes in chemical concentrations, including low oxygen (hypoxia) and high carbon dioxide (hypercapnia). Both hypoxia and hypercapnia are signs of breath holding and both are detected by the chemoreceptors. These receptors send nerve signals to the vasomotor center of the medulla which eventually overrides the conscious breath holding.
The breaking point can be postponed by large lung inflations, hyperoxia and hypocapnia, and it is shortened by increased metabolic rates.
Reference
- Parkes, Exp Physiol (2006); 91(1): 1-15
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29$\begingroup$ In addition: even IF you could hold your breath 'till unconsciousness, because it's a conscious act you'd start breathing again as soon as you're out. $\endgroup$– SuthekCommented Jun 4, 2018 at 12:12
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3$\begingroup$ My understanding (from dim-and-distant Chemistry O-Level days) was that it's primarily the build-up of carbon dioxide that prevents you holding your breath long-enough to pass-out/die... breathing into a bag containing a CO2 adsorber would/may allow this to happen. $\endgroup$ Commented Jun 4, 2018 at 14:45
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8$\begingroup$ @TripeHound Hyperventilating, to reduce CO2 build up, is one of the main causes of Shallow Drowning - it not only can, but does happen. $\endgroup$ Commented Jun 4, 2018 at 15:59
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3$\begingroup$ @MasonWheeler I've heard similar stories, but couldn't find peer reviewed work on it; my answer is based on a sound paper in a credible journal, at least afaik $\endgroup$– AliceD ♦Commented Jun 5, 2018 at 10:41
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2$\begingroup$ @cgTag Yes, if they didn't hyperventilate or have some other health issue. Though note that you only really breathe in a small amount of water - the trachea gets sealed on contact with water - and this phase usually only lasts for a few seconds before unconsciousness sets in (the reflexive breath triggers only a short while before cerebral hypoxia in most people). There's still some time to save the victim afterwards - near drowning isn't rare. There's even some extreme cases in cold water where people survived the anoxia for minutes without any permanent damage (even 60 minutes!). $\endgroup$– LuaanCommented Jun 6, 2018 at 6:37
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Counterexample: At least some people can train themselves to hold their breath until they pass out, and if this occurs underwater they will almost certainly die by drowning.
When I was in military service I became friends with some U.S. Navy SEALs. They go through a notoriously difficult training and selection process (BUDS) that has been well documented. Among the program's "evolutions" are tests in which candidates have to solve problems to access SCUBA units while submerged in pools or water tanks (and while being harassed by instructors). It is common for candidates to pass out during these tests, because if they surface for air they fail the test. (And these are people who self-select as very motivated to not fail at any cost.) Apparently the tests weed out candidates who are prone to panic as they lose oxygen and can't override their physiological instinct to breath.
I spoke to one graduate who passed out during one such evolution (but succeeded on a second attempt). He noted that after that incident he lost any fear of drowning, because he realized that if he ever found himself in a situation where he was running out of oxygen he would not feel panic and would just fall unconscious before drowning.
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2$\begingroup$ @Trilarion: Yep, just added link to news report on the subject. Notable quote from that article: “What you’re seeing in the data is more rigorous documentation,” Davids said, suggesting that five students losing consciousness in four months wasn't unusual at BUD/S. $\endgroup$– feetwetCommented Jun 5, 2018 at 10:34
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4$\begingroup$ A similar effect (Wikipedia, check the references) is why swimming pools often ban distance swimming underwater: hyperventilation reduces CO2 in the body, even to the point where lack of oxygen causes blacking out first, but more often enough that the swimmer doesn't have time to surface after the urge for air becomes strong. If the SEALs are hyperventilating first, and determined to stay under, no wonder they're passing out. $\endgroup$– Chris HCommented Jun 5, 2018 at 11:10
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$\begingroup$ I'd expect that training could make this more achievable. Even so, when I witnessed this done it was a female classmate in 6th grade. It's at least possible for the untrained. $\endgroup$ Commented Jun 5, 2018 at 17:45
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10$\begingroup$ Hyperventilation is a special case: The urge to breathe is not triggered by lack of blood oxygen, but by excess of blood CO2. Hyperventilating substantially decreases your blood CO2, but only marginally increases your blood O2. In other words, it delays your urge to breathe without significantly delaying your need to breathe. $\endgroup$ Commented Jun 5, 2018 at 19:31
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1$\begingroup$ This counterexample does not support an ability kill yourself by holding your breath. You pass out, then something happens because you aren't conscious (you drown, under water). The same thing would happen if you held your breath until you passed out while driving, balancing on a tightrope without a net, sitting in a burning building, skydiving before pulling the ripcord, or running from a murderer. In all of these situations the official cause of death would not be holding your breath. $\endgroup$– De NovoCommented Jun 29, 2018 at 0:01