Yawning could have an overlooked role in regulating fluids in the brain, according to a groundbreaking new study, which also sheds fresh light on what happens when someone tries to stifle a yawn. It was previously thought that the behaviour had evolved mainly to regulate oxygen levels . Alternative theories suggested yawning was meant to signal tiredness to other members of the species. The new study used MRI scans to reveal that yawning reorganised the flow of the cerebrospinal fluid out of the brain. It’s known that this fluid helps remove waste and move key chemicals from the brain, thereby maintaining pressure balance and supporting the organ’s overall health. The study also notes that each person yawns in a slightly different way. “Yawning appears to be a highly adaptive behaviour and further research into its physiological significance may prove fruitful,” the study, published in the journal Respiratory Physiology & Neurobiology, says.…