physiology of sighing
April 15, 2005 5:28 AM   Subscribe

What's the connection between a thought of regret, or of resignation to a negative situation, that causes humans to involuntarily fill their lungs and exhale slowly? Is such sighing learned behavior? Does every culture sigh for this reason? Animals sigh. When my dog sighs, is she laying there regretting she didn't roll in that dead skunk when she had the chance?
posted by stupidsexyFlanders to Science & Nature (19 answers total)
Response by poster: I guess I kind of understand the physiology behind the "contentedness" sigh, when your mind and body are just super-relaxed. And I guess that's what my dog is doing. But I'm puzzled by the "regret" sigh.
posted by stupidsexyFlanders at 5:51 AM on April 15, 2005

Sometimes it can be a relaxing sigh in a way- if you've been thinking about problems and then just sigh and think 'oh well'
posted by lunkfish at 5:55 AM on April 15, 2005

I'm just guessing, but I believe CO2 buildup in the lungs tends to bring on anxiety... maybe this is a biological mechanism for increasing the oxygen intake and bleeding off stress.
posted by rolypolyman at 5:59 AM on April 15, 2005

The dictionary gives inhale as the antonym of sigh.
I think that it is part learned part innate. By learnt, I mean we sometimes do it for the effect (in different ways) - we do it to communicate our feelings to others non-verbally, but of course not always.
By innate I mean that in the process of sighing we often relax or resign ourselves to circumstances - exhaling is a mostly passive action which assists in our relaxing our muscles and we thereby 'sag' - relax/resign/exhale(sigh) are innately joined. We drop our defenses (or at least, relax our muscles) because we can't do anything about the circumstances. In which case it's a type of stress relief.

I'm sitting here 'doing' sighs - there's lots of them, sometimes audible sometime not. You speak of negative sighing. If there's people around, it's apt to more demonstrative isn't it? There's more active control with positive or forced exhaling rather than a passive type. In that situation we're definitely trying to communicate our disappointment.
We also do it when we are alone - that's a tricky one - maybe we have been socialized so well into accompanying negative situations with an audible sigh that we do it automatically. You watch children doing it and even when they are unaware they are being watched they can sigh quite melodramatically - they are practicing what they have seen in adults.
posted by peacay at 6:06 AM on April 15, 2005

Your heart speeds up a little bit when you inhale, and slows down a little bit the further you exhale (try it). The idea of being resigned about a situation means not doing anything, which means being still, which means slowing the blood down and hopefully thinking less about whatever. That's my guess.
posted by airguitar at 6:11 AM on April 15, 2005

I too noticed this recently when my 3-month old nephew sighed. If I remember correctly, it was not a contended sigh, but rather an exasperated, and resigned sigh. Where did he learn that? It seems that it must be innate.
posted by picklebird at 6:12 AM on April 15, 2005

I'm just guessing, but I believe CO2 buildup in the lungs tends to bring on anxiety... maybe this is a biological mechanism for increasing the oxygen intake and bleeding off stress.

Rolypolyman has it. I read about this during treatment for anxiety a few years ago, and put it to good use. Often an anxiety attack will result from nothing more than a perceived shortage of oxygen due to too-shallow or too-rapid breathing, and a few long sighs will short-circuit the process. So I believe sighing is not learned -- that it is an innate function designed to return the lungs to oxygen equilibrium.

One of the docs will be along shortly to explain better, I hope.
posted by Miko at 6:25 AM on April 15, 2005

C02 builds up in the blood. It occurs when we under breathe. If we're stressed we tend to over breathe and blow off C02 (or not).

Sighing is not related to C02. Sighing is psychological behaviour overlaying normal physiological exhalation.
posted by peacay at 6:36 AM on April 15, 2005

Sighing in newborn human infants
posted by Miko at 6:54 AM on April 15, 2005

Maybe this is semantics. That article abstract is talking about taking large breaths = sighing.
We are talking (I thought) about exhaling slowly audibly in the face of a negative situation = sighing.
If you do lower your c02 from hyperventilating then a paper bag over the face or slowing your breath rate will increase the c02 levels and will help you relax. But in the normal course of stressful events we don't hyperventilate although we may breathe more deeply than normal.
So I'll concede a 1/2 point.
But I think it's got much more to do with a behavioural mechanism - that single sigh helps us relax (and communicate our feelings) and afterwards our breathing rate and c02 levels return to normal (if it was actually altered in the first place - and I wouldn't think that's very often the case)
But if we're thinking regret.....that's more contemplative anyway....more likely you were relaxed.

I think we are really tiptoeing or at least dancing through a semantical minefield on this question. Definitions are pretty well needed.
posted by peacay at 7:19 AM on April 15, 2005

Response by poster: first, it's definitely not demonstrative, or a means of communicating to others -- at least as I've experienced it. It's completely involuntary, often when I'm alone, and I notice it only after the fact. Anyone else?

And it's about taking a large breath AND exhaling it (how could it be otherwise?)

The suggestion that it's a response to anxiety seems to make sense, but how the intake/exhale biologically calms you down, or what body changes prompt the intake/exhale, is still unclear, unless I'm just dense. (sigh)
posted by stupidsexyFlanders at 7:51 AM on April 15, 2005

My mother yells at me when I sigh. I always thought it was just a mechanism for taking a really deep and chest-relaxing breath, but apparently to her it communicates annoyance or something.
posted by casarkos at 9:10 AM on April 15, 2005

My understanding is that anytime your exhale lasts longer than your inhale there is an inate calming effect. A lot of yoga breathing/breathing meditation is based on this. Or so I have been told. I don't know that there is a connection ot sighing, but it would make sense.
posted by OmieWise at 10:53 AM on April 15, 2005

Just with respect to the question, and not getting into things like why do dogs sigh, I think that thoughts of regret and negative situations have you breathing shallowly, and so when you release the stressful thoughts your body snaps back to a better state. Or perhaps the stress warnings from your body cause you to release the idea... who can say.
posted by fleacircus at 11:36 AM on April 15, 2005

in the normal course of stressful events we don't hyperventilate although we may breathe more deeply than normal.

Actually, in stressful events, we breathe more shallowly and rapidly than normal. That's why the deep intake, followed by audible exhale, makes a calming difference. It is never a conscious decision, at least on my part.

I also sigh a lot (to the point where boyfriends have been driven crazy asking me 'what's wrong?' when there's nothing wrong...) And I, too, do it even when alone.
posted by Miko at 1:38 PM on April 15, 2005

Like most behaviour, sighing seems to be partly instinctive and partly an affectation. I'm not sure what the biological mechanism is but I don't think anyone will deny that sighing/deep-breathing has a short-term stress-relieving effect. But it's obvious that people have adopted sighing as a subtle means to communicate exasperation. I find it quite annoying.
posted by randomstriker at 4:23 PM on April 15, 2005

Response by poster: But it's obvious that people have adopted sighing as a subtle means to communicate exasperation.

People also roll their eyes to communicate the same thing. I'm not asking about voluntary behavior, I'm curious about the involuntary physiological response to an emotional stimulus.
posted by stupidsexyFlanders at 10:01 PM on April 15, 2005

This, this and this add a little. Too bad the 3rd is only an abstract. You could sift this lot.
Again, I think 'sighing' is a term applied to lots of situations that aren't the same - demonstrated well by googling: lots of different definitions/criteria/situations etc

And I'm not trying to be argumentative here but merely wondering - when it's an 'involuntary' sigh at an emotional moment - isn't it still possible that we just aren't aware that it's voluntary? - we do lots of things automatically.

In any case, I still think it comes back to stress relief by breath control +/- levelling off C02 levels. (And also communication sometimes - via socialization growing up is why, even if we are unaware) [so: background innate with voluntary overlay]
It's a good Q SSF.
posted by peacay at 11:11 PM on April 15, 2005

ps. I spoke to my pediatrician neice and GP uncle today - they generally agree with what I've outlined - and they also reckon that it's voluntary in the case of emotional response and that the term 'sigh' is applied to a whole range of phenomena.
posted by peacay at 2:48 AM on April 17, 2005

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