Voluntary brain damage?

November 22, 2006 6:32 PM

Can I hurt myself holding my breath?

How long can I hold my breath (voluntarily and consciously) without hurting myself? A friend and I tried holding it more and more, once a day, and eventually got up to three minutes-- at which point we remembered that old factoid about your brain dying after 4 minutes without oxygen.

Not wanting that, we stopped, but I still hear about people holding it for 5 or 6 minutes. Are people who enjoy holding their breath so long already feeling the effects? Should I start up again?

Yes, I know this is a worthless endeavor, and if you're curious we would try it sitting down, eyes closed, with another person timing. Never passed out.

On a side note, my girlfriend said that holding your breath till you passed out and fell on Gymnastics mats was all the rage when she was in third grade. The game had a name, but she can't remember it.

posted by conch soup to health & fitness (11 comments total)

I am absolutely not a doctor, but I've always been told that if you're consciously and voluntarily trying to hold your breath you'll pass out and start breathing again before you do any brain damage.
posted by christinetheslp at 6:35 PM on November 22, 2006

There seems to be some misunderstanding here. The limiting factor on holding your breath isn't oxygen, it's carbon dioxide.

At the point where you absolutely cannot resist and are forced to start breathing again, there's still a lot of oxygen in that air. It starts at 21%, after all. But in terms of getting rid of carbon dioxide, you can't really increase the amount in the air in your lungs beyond a couple of percent.

The urge to breath is not caused by low oxygen level in your blood. Your brain doesn't have any mechanism for detecting that. It's caused by buildup of carbonic acid in the blood plasma.

That's why breathing in a pure nitrogen atmosphere is so deadly. You get no oxygen, but excess carbon dioxide is carried away normally, so there's no feeling of distress. You'll pass out without even realizing there's anything wrong.

High levels of carbonic acid in the blood can be dangerous; that's why our brains are evolved to detect it, and why it causes an overwhelming urge to breath. If you're risking anything with your experiments, that's it. (Medically it's known as "respiratory acidosis".)

And the reason you need to pant heavily for a minute or two afterwards isn't to rebuild oxygen levels, it's to dump all the excess carbon dioxide and restore your blood pH to proper levels.
posted by Steven C. Den Beste at 6:57 PM on November 22, 2006 [1 favorite has favorites]

The game was called "Pass Out" at my school.

Free divers (like Meghan Heany-Grier) warn never to dive for more than 90 seconds.

According to Wiki's page on Apnea, after 1 minute your oxegen is depleted, at 3 minutes you are begnning to get "permanent brain damage" and after that comes black-out and death.
posted by Pollomacho at 6:59 PM on November 22, 2006

>that old factoid about your brain dying after 4 minutes without oxygen

Surely that means "four minutes with the blood flow to your brain stopped and no oxygen reaching it at all"?

Four minutes holding your breath isn't four minutes of your brain getting no oxygen at all.
posted by AmbroseChapel at 7:43 PM on November 22, 2006

The problem won't be holding your breath. The problem will be holding your breath, passing out, falling down and smacking your head on something hard.
posted by frogan at 8:34 PM on November 22, 2006

Frogan-
Hence the note that "we would try it sitting down."

FYI, it was a big comfy couch with no sharp corners to hit one's head on.
posted by conch soup at 8:52 PM on November 22, 2006

There is a wikipedia article on the 'game' that your girlfriend is talking about: Choking Game. See Section 2, "Self-induced hypocapnia."

It's difficult to make yourself pass out just by holding your breath, but if you hyperventilate, then hold your breath and then try to blow out against your closed mouth (or have someone 'bear hug' you to compress your lungs), it can knock you out. I've heard stories of this happening to people who are trying to hold their breath underwater (because in preparation for diving, they'll hyperventilate, then take a deep breath and go under, and the water pressure acts like the "bear hug"). I've never seen it happen in person, though.

I'm not sure that you can really hurt yourself by trying to consciously hold your breath, assuming you're sober and alert, don't hyperventilate first, and not underwater or obstructing your airway with anything. I would think that before you did serious damage to your brain, the urge to breathe would become too great. I was always told that when little kids try to get attention by holding their breath, the best approach was just to ignore the behavior, since it wouldn't work anyway.
posted by Kadin2048 at 9:11 PM on November 22, 2006

I remember reading that if you hold your breath long enough, the brain can trigger an involuntary reflex gasp, meaning that it is impossible to hold your breath indefinitely on willpower alone. This will presumably happen before any substanial harm can happen to the body.
posted by TheOtherGuy at 9:47 PM on November 22, 2006

If you have high blood pressure, it'll make it higher for a short time, but there shouldn't be any lasting damage, unless you do it a lot.
posted by fvox13 at 11:06 PM on November 22, 2006

The relevant term you may want to look up is 'apnea' or more specifically 'static-apnea' (i.e. breath holding without movement). The wikipedia apnea page and free-diving page have some more info.

Following on from SCDB's answer, it's worth nothing that hyperventilating before holding breath is a bad idea, as it does not increase oxygen, but rather decreases carbon dioxide, leading to longer time before the brain's respiratory center kicks in.
posted by MetaMonkey at 1:38 AM on November 23, 2006

You'll be fine, but whatever you do: don't hold your breath under water if you are unattended. Sounds obvious, but aspiring freedivers have drowned in the bathtub practising their breath holding.
posted by SpacemanRed at 5:23 AM on November 23, 2006