A deep sigh and intake of breath with arms stretched back in a lazy arc: yawning is rarely a good look when it comes in the middle of a conversation. But yawning - as rude as it can come across - is probably healthy, researchers now believe.

University of New South Wales (UNSW) neuroscientists say yawning appears to clear waste from the brain - a "speculative" finding that potentially clears up at least some of the mystery behind the reflex.

In tests based on magnetic resonance imaging (MRI) scans, the team found that yawning triggers a "specific manoeuvre in which cerebrospinal fluid and venous blood move out of the skull together."

According to UNSW, the fluid "is important because it cushions and protects the brain and spinal cord from injury and also helps carry nutrients in and waste products out."

"Yawning is a body movement that can influence the flow of fluids around the brain," said Lynne Bilston of the UNSW and Neuroscience Research Australia (NueRA), whose team's findings have been published in the July 2026 edition of Respiratory Physiology and Biology.

"There has been speculation that yawning can help clear waste from the brain, but so far there has not been solid proof," Bilston added.

Perhaps even more intriguingly, the team believe they have uncovered another facet of yawning - that each person does so with a particular movement of the tongue and therefore could be identified by a yawn as easily as with a fingerprint.

"Yawning remains very mysterious, even though it’s a primordial process that has been preserved throughout evolution," said researcher Adam Martinac, who explained that "nobody has really worked it out for certain."