Deep sighs are not only satisfying—they’re healthy
There’s something to be said for a good sigh. Sometimes this deep exhale is not only psychologically satisfying, but physically restorative. According to a study published in the journal Scientific advancesNew evidence indicates that sighing really is a way to help reset your body, especially the fluid that coats your lungs.
Pulmonary surfactants are a special group of phospholipids and proteins that line the outside of your respiratory organs. They essentially act as a lubricant for your lungs by reducing their surface tension when you breathe. They are also essential for your health. More than half of all premature infants born before the 28th week of pregnancy are low on fluid, causing some of the alveoli in their lungs to collapse. In the late 1980s, researchers discovered that this often fatal disease could be alleviated by extracting similar surfactants from animal lungs and injecting them into the lungs of a premature baby.
“It works very well in newborns. The fluid covers the entire surface, making the lungs more deformable or, for a more technical term, compliant,” Jan Vermant, a researcher at ETH Zurich and co-author of the study, said in a statement.
However, COVID-19 has complicated things. Vermant and colleagues cited about 3,000 adults developing acute respiratory distress syndrome during the pandemic. In these cases, the fluid transplant procedure used on premature babies did not work.
“This shows that it’s not just about reducing surface tension,” Vermant explained. “We believe that mechanical stresses within the fluid also play an important role. »
Since then, he and an international team of researchers have experimented with simulating normal, deep breaths in the laboratory and then measuring the surface stress of lung surfactants. They found that surface stress on the lungs decreased significantly after particularly deep breaths, indicating a physical explanation for the relief that often accompanies a deep sigh. Why it helps to understand pulmonary surfactants not as a single layer of fluids, but as multiple layers.
“Directly at the boundary with air there is a slightly stiffer surface layer. Below that there are several layers that should be softer than the surface layer,” described Maria Novaes-Silva, co-author of the study.
These layers work best when they are in balance with each other, but sometimes they get out of balance. When they’re out of balance like this, the best way to adjust the layers is to take a deep breath. By forcing the surfactants to stretch and compress more intensely, the lung fluid essentially resets its outer layer.
“It is a state outside the limits of thermodynamic equilibrium that can only be maintained by mechanical work,” Vermant said. He also cited previous clinical research that showed that while lung conformation inevitably changes over time, it is exacerbated by continued shallow breathing.
Vermant’s team hopes their findings can lead to better treatments for lung failure in adults. One way forward might even be to concoct artificial surfactants, identifying the components that make up each individual fluid layer. In the meantime, this is the perfect time to pause and take a deep, literally healing breath.
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