Overview
- MRI scans showed yawning triggered a coordinated outflow of cerebrospinal fluid and venous blood from the skull.
- The reflex increased cerebrospinal fluid movement compared with normal breathing and did so more often than deep breaths.
- Yawns followed a repeatable, involuntary sequence controlled by the brainstem that kept going even when people tried to stifle it.
- The study tracked 22 healthy volunteers and was published in the journal Respiratory Physiology & Neurobiology.
- The authors propose roles in waste clearance, solute transport, and brain cooling, and they stress the findings are early and need targeted follow-up, including tests in conditions like migraine.