February 4, 2026
Do not read while sleepy
Yawning has an unexpected influence on the fluid inside your brain
Yawning reshuffles brain fluid—and commenters want “yawn to unlock”
TLDR: A new MRI study suggests yawning reorganizes brain fluid and boosts fresh blood flow to the head, hinting at a real physiological purpose. Commenters battled paywalls, shared an archive, joked about “yawn to unlock,” and debated whether contagious yawning is an evolutionary trick—proof that even a yawn can start a flame war.
A small MRI study says your yawn isn’t just “I’m bored”—it actually rearranges the fluids in your head, pushing brain fluid and blood out together and making room for a surge of fresh blood. Internet reaction? Chaos. First, the paywall outrage (“paywall,” sighed one), immediately rescued by a hero dropping an archive link while another sleuth hunted for the science with a bioRxiv preprint.
The twist that each person has a unique “yawning signature” turned the thread into a comedy club. One commenter imagined the future: “yawn to unlock.” Others side-eyed the article’s odd image and asked why contagious yawning spreads like a meme in real life. The strongest take: contagious yawning must be evolution’s weird little feature, even if the reason isn’t obvious. Cue debates over whether it coordinates group alertness, cools the brain, or just makes meetings unbearable.
Meanwhile, the study’s vibe: yawns send brain fluid (the clear stuff cushioning your brain) and blood out toward the spine—not like a deep breath, which moves them in opposite directions—and boosts incoming blood by more than a third. The lab even used yawning videos to trigger yawns in the scanner, because of course yawns are contagious. Internet verdict: fascinating, mildly cursed, and dangerously close to becoming a biometric login.
Key Points
- •MRI scans of 22 adults showed yawning reorganizes neurofluid dynamics differently from deep breathing.
- •During yawning, CSF and venous blood flow were directionally coupled, often moving together away from the brain toward the spinal column.
- •Deep breathing typically showed opposing flows: venous blood out of the brain while CSF flowed in.
- •Yawning boosted carotid arterial inflow by over one-third compared with deep breathing.
- •Mechanism and CSF volume changes remain unclear (estimated a few millilitres); researchers suspect coordinated neck, tongue, and throat action and observed individual yawning “signatures.”