Research Hit: What Yawning Does to Your Brain
New research answers an old question of what yawning is good for, possibly…
Do we know why we yawn?
Not really, it has been a mystery for many years. We do it, chimps do it, it is infectious to boot. It may have a signalling function but it was also thought to increase blood flow to the brain to relieve fatigue. Or at least that was the assumption.
So it’s not true?
Well, yes, and no. A group of researchers from the University of New South Wales in Australia put 22 healthy participants into a MRI scanner to observe what happen in the brains and surrounding vessels in the neck while they:
- yawned
- took deep breaths
- stifled yawns
- and breathed normally
The assumptions was that a deep breath and yawn had similar mechanisms and hence also impacts. And there was a similarity in blood flow with both triggering an increase in blood flow away from the brain.
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But there was also a surprising difference and this was in the Cerebral Spinal Fluid (CSF). Our brain sits in this fluid and it is also our brain’s waste disposal system.
But unlike deep breaths which moves CSF into the brain, yawns moved CSF out of the brain.
Is this detoxifying the brain then?
That is a possibility. There is also large surge of blood into the brain in the first part of the yawn. It could be that yawns serve multiple purposes such as cooling the brain also.
Of note is that larger brains tend to trigger more yawns — that’s a nice piece of trivia, and my excuse!
Oh lucky you!
But another thing the researchers noted is that there also seems to be a personal signature of yawning — meaning the way and the reasons may be very individualistic.
So we’ve learned more but are still confused?
Yes, that will get your brain working, won’t it!
And funnily enough I think writing this has also had an infectious effect — I have been constantly yawning…but maybe that’s just my large brain ;)
Originally published on my Substack
Reference
Adam D. Martinac, Stean Waters, Robert A. Lloyd, Lynne E. Bilston
Biomechanics of yawning: insights into cranio-cervical fluid dynamics and kinematic consistency
doi: https://doi.org/10.64898/2025.12.17.695005
