Tiredness, sadness, and relief all feel very different, and yet sighing somehow seems to complement each emotional state. But why do we do it? There have been lots of theories, but no one is quite sure. Now researchers have filled in an important piece of the puzzle: They have discovered the neurological pathways responsible for the frequency of sighing, independent of regular breathing. The study was published today in Nature.
A sigh, defined here as a deep long breath about twice the volume of a typical breath, is of course involved with your emotions. It also serves as a sort of stretch for your lungs—a periodic deep breath inflates the alveoli, tiny sacs in the lungs where oxygen and carbon dioxide pass in and out of the blood.
That stretch is critical to keep lungs working properly. “When alveoli collapse, they compromise the ability of the lung to exchange oxygen and carbon dioxide,” Jack Feldman, a neurobiologist at UCLA and one of the study authors said in a press release. “The only way to pop them open again is to sigh, which brings in twice the volume of a normal breath. If you don’t sigh, your lungs will fail over time.” Read more