You’re not just merely getting exasperated or unleashing an emotion when you’re heaving a sigh.
Sighing is actually a life-supporting reflex that helps preserve one’s lung function, according to new research by Stanford and UCLA researchers who pointed out two small groups of neurons in the brain stem that make ordinary breaths turn into sighs.
The findings – which may help future patients who cannot deeply breathe by themselves or who have frequent, health-damaging sighs – were published in the journal Nature.
“Sighing appears to be regulated by the fewest number of neurons we have seen linked to a fundamental human behavior,” reported study author and neurobiology professor Jack Feldman from UCLA.
Sighing lends insight into the brain stem cell network that produces breathing rhythm. The brain’s “breathing center” is composed of different neurons, each functioning like a button that activates a specific type of breath.
Author and biochemistry professor Mark Krasnow from Stanford University explained that a button produces regular breathing, while another programs sighs. Other buttons also create sniffs, yawns, coughs, and even cries and laughs.
Sighing – an involuntary deep breath – proves important to the functioning of the lungs. A person, on average, sighs every five minutes, translating to 12 sighs every hour.
Its purpose is inflating the alveoli, which are the small, delicate, balloon-like sacs in the lungs for oxygen and carbon dioxide exchange. Alveoli collapse compromises the lung’s ability for this exchange, said Feldman, so sighing, or delivering double the volume of a regular breath, is the only technique to pop them open again.
However, it is crucial to limit this reflex in anxiety as well as other psychiatric disorders where sighing becomes damaging.
Sighing is shared by humans with other animals, a discovery stemming from two separate research inquiries of Krasnow and Feldman. Based on their experiment, mice can sigh about 40 to a whopping 400 times per hour.
The emotional roots of voluntary sighing remain mysterious. Feldman said that it could be that emotion-processing neurons trigger the outpouring of sigh neuropeptides, something that still needs to be studied.
These findings could help experts develop drugs for inducing sighing in people who do not do them enough, or to control the act in sufferers of disorders that lead to excess sighing.
