I did not read the article. But my question is - does it mean yawning (like trying to yawn on purpose which in my case will make me "really" yawn soon) influenc

I did not read the article. But my question is - does it mean yawning (like trying to yawn on purpose which in my case will make me "really" yawn soon) influences those fluids inside my brain? Or - a change in those fluids makes me yawn?