It turns out that primarily breathing through the mouth isn’t good for your health compared to breathing through the nose, a new study finds.

Breathing through the nose rather than the mouth can lead to lower blood pressure and an overall more relaxed body, lowering the risk of heart disease, researchers found.

“This work advances our knowledge of how nasal breathing affects clinically relevant cardiovascular variables,” concluded the research team led by Joseph Watso, an assistant professor of health and human sciences at Florida State University in Tallahassee.

More than half of U.S. adults say they primarily breathe through their mouth rather than their nose, researchers said in background notes.

Breathing patterns can affect blood pressure and heart rate, which are two predictors of heart disease, due to the crosstalk that occurs between the respiratory and circulatory systems.

Nose breathing has been shown to relax the airways and improve the efficiency of breathing, but up to now its effects on heart health have not been fully explored, researchers said.

For their study, researchers recruited 20 young adult volunteers who were randomly asked to breathe through either their nose or their mouth while at rest or exercising on either a treadmill or a stationary bike.

Researchers found volunteers at rest had a lower average and diastolic blood pressure when they breathed through their nose. Diastolic blood pressure is pressure within the arteries in between heartbeats.

Nasal breathing also shifted the body’s nervous system into a “rest and digest” rather than a “fight or flight” mode, researchers added.

However, that was only during rest. When exercising, there appeared to be no difference between nasal or mouth breathing.

“We interpret the collective data to suggest that nasal compared with oral breathing provides modest, but potentially clinically relevant, improvements in prognostic cardiovascular variables at rest, but not during exercise,” the researchers wrote.

The new study was recently published in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.