Yawning may cool and cleanse the brain by moving brain fluid, study finds

A UNSW study using MRI on 22 volunteers shows yawning shifts cerebrospinal fluid flow in the brain in a way that deep breaths do not, and also increases brain blood flow. This pattern could help cool the brain and aid waste clearance, suggesting yawning has a physiological function beyond signaling boredom or empathy. The yawning motions appear tightly coordinated by brainstem circuitry and often accompany swallowing. The work is a preprint and not yet peer‑reviewed, and further research is needed to confirm these findings in everyday life.