Taking a deep breath really does calm you down by triggering neurons in your brain which tell the body it is time to relax, a new study has found.

Researchers at Stanford University School of Medicine and the University of California have identified 175 brain cells which spy on the breath and alter state of mind accordingly.

For thousands of years yoga students have been taught that controlling their breathing can bring a sense of calm, while it is a well known truism that taking a few deep breaths can lower rage. But until now nobody knew why it worked.

The new study suggests that it is indeed possible to reverse engineer your mood simply by altering breathing.

“If something’s impairing or accelerating your breathing, you need to know right away,” said Dr Mark Krasnow, professor of biochemistry at the Stanford University School of Medicine.

“These 175 neurons, which tell the rest of the brain what’s going on, are absolutely critical.”