Sometimes it happens that you sigh without thinking too much, as if your body had decided to take a break on its own. That air that enters slowly and deeply, then comes out in a long breath, almost seems to free something. And indeed, it really does.
According to a study published in the journal Science Advancesa deep sigh is not just an emotional valve, but a real physiological reset. Scientists at ETH Zurich have discovered that breathing deeply helps the lungs renew the fluids that line them, allowing them to work better. Basically, every time we sigh, our lungs do a little “system reboot”.
Inside the lungs there is a substance that is little talked about, but which does an incredible job: pulmonary surfactants. It is a mix of phospholipids and proteins that covers the alveoli, the microscopic air sacs where the exchange between oxygen and carbon dioxide takes place.
Think of them as a thin veil that allows your lungs to expand effortlessly, just like oil moves a gear.
Without this layer, breathing would become difficult, almost painful. Not surprisingly, many premature babies born before the 28th week do not produce enough surfactant, and their lungs are at risk of collapsing. In the 1980s, doctors managed to save thousands of children by injecting a natural surfactant extracted from animals into their lungs.
Researcher Jan Vermant, one of the authors of the study, explains that this treatment works perfectly in newborns: the fluid is distributed evenly, making the lungs more elastic and “compliant”. But in adults things get complicated.
When breathing deeply becomes the best natural therapy
During the COVID-19 pandemic, many patients with acute respiratory distress syndrome did not respond to treatment with surfactants. It was a wake-up call. According to Vermant, it’s not just about reducing surface tension:
The mechanical forces acting on the fluid are also fundamental.
The team thus recreated the movement of the lungs in the laboratory, simulating normal, deep breaths. The results are surprising: after a deep breath, surface tension decreases sharply, improving the fluid’s ability to adapt to movement.
Simply put: when you sigh, you are literally helping your lungs regain balance.
The explanation is almost poetic (but not too much): the surfactant is not a single layer of fluid, but a series of overlapping levels. The outer one is more rigid, the ones underneath are softer. If these layers lose harmony, deep breathing “massages” them and brings them back into balance. It’s like when you iron a shirt that’s too wrinkled: you need a little heat and a nice shot of steam to get it back into shape.
Deep breathing as a reset of the body (and mind)
Vermant explained:
This state can only exist thanks to constant mechanical work. Those who always breathe shallowly reduce the flexibility of the lungs.
This is the case of those who spend hours sitting, breathe short in front of the computer or live in stress apnea. In the long run, this type of “lazy” breathing makes the lungs less elastic and promotes that feeling of chronic fatigue that we never know how to explain.
On the contrary, a deep breath – the one that starts from the belly and rises slowly – reactivates the body and calms the mind. You don’t need to be an expert in yoga or meditation: just take a few minutes, breathe in mindfully and let the air do its job.
Scientists now want to create artificial surfactants capable of mimicking the different natural layers of lung fluid, to help those suffering from respiratory failure. But until that moment, the best medicine remains the simplest: breathe deeply, every day, several times. An automatic gesture that becomes, if you really do it, an act of self-care.
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