ETH study reveals Why deep sighs are good for people
Can a deep sigh make you feel good? A Swiss study provides insights into the effect on the lungs - and the significance for our breathing.
18.10.2025, 10:21
dpa
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- Researchers at the EZH Zurich have discovered that sighing is important for lung function.
- It ensures that fluid is distributed in the lungs and makes them more malleable for breathing.
- Conversely, it has been shown that breathing becomes increasingly difficult when breathing is constantly shallow.
According to an international study, sighing can improve lung function. The associated deep breathing plays a decisive role in restoring the malleability of the lungs, write scientists led by the Swiss Federal Institute of Technology in Zurich (ETH) in the journal "Science Advances".
Basically, the lungs expand when we inhale and contract when we exhale. During this movement, the tissue and the surface of the organ offer resistance. The fluid on the surface of the lungs reduces this resistance - and, as the study shows, particularly after deep breaths.
"The fluid wets the entire surface, making the lungs more malleable - or to use a technical term - more pliable," explains study leader Jan Vermant in an ETH press release on the study.
Surface tension decreased after deep breaths
In the laboratory, the materials scientists tested how the lung fluid behaves under different scenarios. To do this, they simulated the movements of normal and particularly deep breaths and measured the surface tension of the fluid.
"This tension influences how flexible the lungs are," says Vermant. The more pliable the organ is, the less resistance there is when contracting and expanding - and the easier it is to breathe.
The measurements in the laboratory showed that the surface tension decreased significantly after deep breaths. This could physically explain the liberating feeling in the chest that often occurs after a deep sigh, the researchers emphasize.
Layers should be different
Their explanation for the phenomenon: the fluid on the surface of the lungs, which is supposed to ensure that the organ can expand and contract properly when breathing in and out, has several layers. Ideally, the top layer should be stiffer, while the layers below should be softer and more delicate, explains lead author Maria Novaes-Silva.
With shallow breathing, when the fluid only moves a little, the layering of the fluid decreases over time. In contrast, occasional deep breaths could restore the ideal stratification.
This is consistent with clinical observations that breathing becomes increasingly difficult with constantly shallow breathing, the group writes. The findings could point to new ways of treating lung problems.
