[DFHippie]

The one that works is the one that people do without special training: sighing*. There had to be some reason why people sigh.

* Yes, this is an odd sort of sighing, but it isn't that different from spontaneous sighing. And people also hyperventilate on their own, but mostly preparatory to diving or holding their breath for some other reason.

[klyrs]

> And people also hyperventilate on their own, but mostly preparatory to diving or holding their breath for some other reason.

It's common for people to hyperventilate in the midst of a panic attack, and the common advice I've seen is to encourage a panicked person to take deep breaths. Strange to see it as a consideration for beneficial effects. As a kid I'd hyperventilate to feel dizzy because it was fun (oops was I getting high?)

[kbutler]

Except sighing isn't generally a natural response to stress, but a response to boredom.

So maybe it's consciously emulating a natural behavior matching a lower-stress state, to help shift to that state.

From personal experience, the deep inhalation preceding a sigh (extended exhalation) is also helpful.

[nobodyandproud]

A sigh of frustration is pretty common. Biting one’s tongue and taking a breathe.