I am also looking for an answer to the same question. I was trying to find an explanation for why when I am sitting next to my 16 year old daughter she frequently takes very deep sighs. I asked her if she is conscious of this and she says that she doesn't do it purposely, but it does make her feel better bacause it expands her chest. I don't think that it could be anxiety if we are just watching tv or playing a game.
I thought that it might have something to do with the fact that sighing releases and distributes surfactant which loosens lung pressure and allows them to expand easier. Normally, one takes a sigh about every fifth breath or so, but it usually is not noticable.
Just a few other notes. She has had many bouts with croupe when she was about a year, she eats alot yet is very thin, and has never been very active. She has always had difficulty with aerobic exercise and losing breath easy.
If anyone can be of help I would appreciate it.
mmmcavins
it could be a sign of anxiety