Yawning and Brain Clearance: MRI Reveals CSF Flow During Yawns and Sleep's Role in Brain Waste Removal

The podcast spotlights a yawning study led by Dr. Lynn Bilston that uses MRI to track cerebrospinal fluid flow around the brain during yawns. The team finds that yawning aligns CSF and blood flow so that waste is moved out of the brain as fresh blood flows in, a pattern different from that seen with a deep breath. The discussion explains how yawning mechanics may be driven by a central pattern generator in the brainstem and uses a washer analogy to describe CSF mixing. The show then explores sleep and health, citing CDC data that about a third of Americans do not reach seven hours of sleep, with disparities by race and age, and the health risks of short sleep. Contagious yawning is also considered.

• Yawning coordinates CSF and blood flow
• Deep breathing does not replicate yawning
• Yawning appears hardwired
• Sleep duration and consistency affect health

Overview

This episode centers on yawning and how a specific interdisciplinary study used cutting-edge MRI methods to observe what happens to cerebrospinal fluid (CSF) and blood during a yawn. Led by biomechanical engineer Dr. Lynn Bilston at the University of New South Wales, the work arose from a project on how breathing influences CSF flow around the brain and spinal cord. The researchers sought to determine whether yawning, which involves a distinctive mouth opening and tongue motion, could modulate CSF clearance, a crucial process for removing brain byproducts. The podcast also features a segment on sleep health with CDC data discussed by sleep researcher Dr. Stuti Jaiswal, linking sleep quantity and consistency to various health outcomes. Together these conversations illuminate the links between yawning, brain clearance, and sleep phenomena.