Lots of times, when some great tragedy occurs, one often hears journalists and bystanders alike softening the blow of having some person die by saying something like "at least they died instantly" or "they died instantly, so they didn't suffer."

I've always wondered whether there was in fact a scientific way to determine whether or not a certain method of death is instant or not.

Would dashing one's head having fallen from a high distance lead to "instant death"? What about a high velocity hollow-point bullet? Complete decapitation, such as found in the guillotine? Is there a technical definition for the requirements of "instant death" available somewhere? I'd appreciate anyone making the science more clear for me.

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    Perhaps we should define instant before we try to answer the question. Good question though.
    – Luke
    Commented Mar 30, 2011 at 19:56
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    A definition for "life" would also be helpful.
    – Shog9
    Commented Mar 30, 2011 at 19:58
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    @Billare I was just pointing out that all periods of time are measurable. The phrasing of your question is a bit subjective. I think you are really asking about the use of the phrase and what it means. I hope my answer helps to clarify your question.
    – Luke
    Commented Mar 30, 2011 at 20:04
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    @Billare: clearly if the cause of death (say an explosion) travels faster than neural impulses, it's practically impossible to perceive one's death. If furthermore the cause is highly destructive (again, an explosion), the body gets destroyed very quickly. Given that an instant is a "a very short space of time", I think this fits your request correctly (I know, that's not what you wanted to know...)
    – Sklivvz
    Commented Mar 30, 2011 at 20:28
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    @Sklivvz, if I fall out of a plane, fall for 30 seconds knowing I am going to die, and then land on my head faster then neural impulses, is my death instantaneous?
    – Oddthinking
    Commented May 25, 2011 at 2:55

3 Answers 3


Well, part of the problem is that when we talk about death, there are multiple definitions.

Medically, you have "clinical death" and "brain death." There is also the definition of death which means "the end of life." The latter is even more of a problem because where most people consider "life" to mean a certain level of functioning, science defines life based on more than organ functions. Starting at a very young age, in schools, we are often taught that the basic way that science defines life is that life is something that can:

  1. Reproduce
  2. Grow
  3. Move
  4. Have a metabolism (obtain and use energy)

So, starting with brain death, yes, it is possible for the brain to cease functioning almost instantly. While we don't have many details on what the experience is like when the brain is shutting down, we do have studies on the activity in the brain afterward. It is most likely the case that during death, the brain will send signals based on external stimuli, as that is its main function, and because those stimuli are extreme, the brain's activity will probably also be pretty high. Because instant injuries, such as the one mentioned, create irreversible damage to parts of the brain that send and receive signals, instant brain death is possible because it would be much like ripping conductive wires apart that support a larger, electrically-driven apparatus, the parts of the brain affected by the injury would instantly turn off.

Clinical death is a little bit different and is vaguely defined. Generally, clinical death involves stopped breathing, but it can also involve cardiac arrest and the failure of various organs and biological systems. Clinical death is often not considered actual death because someone who is clinically dead can sometimes be revived. So, while someone may suffer injuries that causes clinical death to be sudden, because the brain hasn't necessarily shut down in the event of clinical death, they may actually experience something while they're unconscious and dying. This is what scientists think is responsible for near death experiences which many claim are related to the afterlife. Instead, though, these reports of near death experiences are likely similar to lucid dreams, in which it is difficult to differentiate between what is happening in one's head while sleeping and what is actually happening while awake.

Approaching the question of death as the end of life, as defined by science, is a whole different realm than defining brain death and clinical death. For at least a short time after we die, cellular processes can sometimes continue, even when the heart has stopped, breathing has stopped and the brain no longer is functioning. The cells function as long as their basic structures are in tact and the nutrients they are surviving on are still available. Thus, some of an individual's metabolic processes, like storing fat, will continue to happen for over an hour (probably more) after the brain, lungs and heart have completely shut down. Reproductive cells will function for a while after death and the process of death, itself, will cause an individual to move, sometimes. Because of this, a corpse still satisfies the definition for life that we're often given in grade school science classes. If consider death at this level, the only way instant death could occur is if the cellular structures of the body, including our symbiotic microbes, were instantly destroyed.

When people refer to "instant death," though, in the sense that you describe, they're usually talking about what level of awareness someone has as they're dying. Did they feel pain for some time or did they experience some emotional state as they passed away? In that sense, instant death is not uncommon. Certain types of brain injuries do damage the brain to the point that it can no longer send signals related to processing stimuli. Decapitation may be another matter, though, because the brain may be severed from the body, but it can still send signals for a very short time. There are, in fact, anecdotes about decapitated heads responding to stimuli after being separated from their body (not that anecdotes are great evidence, but that's what we have. I know of no brain scan done on a decapitated head right after it was severed from the body).

There's no technical definition for "instant death." Instead, that is a term used in everyday jargon and not in the medico-science community as some official term. Death is too complex for that, as you can see.

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    Great answer on essentially the ultimate in complex medical topics.Especially for acknowledging the timeline between the inital cessation of function and the point at which it is no longer reversible as well as that "death" is not a precisely defined clinical term(and may never be).Study of the topic continues to be refined as the technology available to observe it grows,and it will be interesting to see what findings come in the future.Especially given the rapid advancement of technologies like fMRI.For an interesting oddity regarding decapitation,check out Mike the Headless chicken. Commented Mar 31, 2011 at 21:14
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    For some perspective,the link here references the American Medical Association regarding death in 1972: jama.ama-assn.org/content/222/1/86.1.extract. And this references an article from the same organization in 2008: jama.ama-assn.org/content/299/18/2232.full. It's not by any means definitive,but can help to illustrate how thoughts regarding death are continually refined as the science progresses. Commented Mar 31, 2011 at 21:33
  • I suspect the line between living and dead will only get blurrier with time Commented Apr 1, 2011 at 3:13
  • My favourite take on the subject is Stephen Wright: "I said everyone dies instantly, no other way to go. You're alive, you're alive , you're alive you're alive, then you're dead.
    – Nthaoe
    Commented Apr 11, 2011 at 13:11
  • Wow, that's some anecdote - and the heart kept on beating for an hour!? (I'd say that if it was quoted in the BMJ and performed by doctors it qualifies as slightly more than an anecdote.)
    – Benjol
    Commented May 3, 2011 at 9:02

Typically when this term is used, it is describing a manner of death in which the deceased felt little or no pain during the process of death.

What does "instant death" really mean? does a pretty good job of answering the question.

In short:

  1. It is difficult to determine exactly when death occured
  2. This usually refers to a rapid loss of consciousness with actual arrest occurring later
  3. When reported by news and media, they aren't always scientifically accurate.

I also like the quip, noting that you always die instantly:

Also, I should probably note that by a somewhat more snide definition, all death is instantaneous. One second you're alive, the next you're dead.

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    It's a snide definition, all right. And more than a little inaccurate. Like most terms with this air of finality, it really depends on what your definition of "is" is. Commented Mar 31, 2011 at 2:03
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    And with another definition, no death is instantaneous as it takes a lifetime to die. Commented May 26, 2011 at 14:43

Yes, although the circumstances are a bit unusual, and outside of them SophieMonster’s response covers situations that are more likely.

The primary situation in which it could be agreed that biological death occurred instantly would be vaporization of the body if someone were close enough to the hypocenter of an nuclear weapon detonation, which is a well documented effect,

Most elements of the Japanese 2nd General Army were at physical training on the grounds of Hiroshima Castle when the bomb exploded. Barely 900 yards from the explosion’s epicenter, the castle and its residents were vaporized.

This does however require that you are close enough to the hypocenter to be exposed to the appropriate temperatures, which are estimated to be around 106 K; otherwise you are likely to die of the secondary effects of the blast instead. Recalling the Hiroshima and Nagasaki bombings, most did not die of the immediate effects but rather the longer term effects of radiation or injuries caused by the bombings, and most things are not vaporized.

Bomb disposal technicians make reference to being turned into "pink mist" which could also qualify; however, without knowing what the yield of a given device is, there is no way to ensure that it would be instantaneous.

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    Any event with a sufficient shockwave [en.wikipedia.org/wiki/Hydrostatic_shock] (e.g. a bullet entering the brain or even a tank round impacting close by) might liquify the brain in an instant as well, without necessarily produce external evidence of the trauma.
    – Michael
    Commented Jun 16, 2013 at 5:21
  • @Michael Good point, at a minimum there would be brain death involved, but what about the rest of the body?
    – rjzii
    Commented Jun 16, 2013 at 14:11
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    The problem with the whole 'dying instantly' question is that more or less by definition it's impossible to ask anyone whether it felt 'instantaneous'... Commented May 12, 2014 at 9:08
  • Or even what "death" is... If you're born without consciousness what does it mean to die instantly? Commented Jan 23, 2015 at 20:02

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