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NATURE'S RESET

Holding in Your Yawns Has a Hidden Cost for Your Body

If this article prompts you to let out a yawn, don’t worry—it’s probably a good thing.

Tamilore OshikanluBreaking News Intern

PublishedMay 5, 2026, 2:18 PM EDT

UpdatedMay 5, 2026, 2:19 PM EDT

Updated May 5, 2026, 2:19 PM EDTPublished May 5, 2026, 2:18 PM EDT

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Yawning isn’t just a sign you’re bored—it may be your brain quietly taking out the trash.

A new study suggests the familiar, uncontrollable reflex does far more than stretch your jaw and fill your lungs. It may actively help flush waste from the brain, regulating the flow of cerebrospinal fluid in ways scientists are only beginning to understand.

Researchers publishing in Respiratory Physiology & Neurobiology used MRI scans on 22 participants to track what actually happens inside the body during a yawn. What they found surprised them.

That wide-mouthed inhale and coordinated head and neck movement triggered a powerful surge of cerebrospinal fluid—the clear liquid that cushions the brain and spine and helps remove metabolic waste linked to neurogenerative diseases, such as Alzheimers.

Compared to normal breathing or even deliberate deep breaths, yawning produced a stronger and more consistent wave of fluid movement near the brainstem and upper spinal canal.

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The team, led by scientists at the University of New South Wales in Australia, compared four conditions—regular breathing, deep breathing, yawning, and suppressed yawning. While deep breaths did increase fluid movement, they didn’t behave the same way.

Yawns pushed fluid outward more frequently and more forcefully. Deep breathing, on the other hand, showed mixed or even counter-directional flow.

That distinction caught researchers off guard.

Neuroscientist Adam Martinac told New Scientist that the difference was immediately obvious in the scans. “The yawn was triggering a movement of the CSF in the opposite direction than during a deep breath,” he said. “We’re just sitting there like, whoa, we definitely didn’t expect that.”

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The study also revealed that a person’s physical attempts to dampen a yawn do not stop the process.

Participants who attempted to hold it in still showed nearly the same internal sequence length. The body went through the motions anyway—just slightly concealed on the outside.

“Once initiated, yawning proceeds as a structured sequence that can be partially masked but is difficult to fully interrupt,” the researchers wrote.

The study also found that both yawning and deep breathing boosted blood flow out of the brain, making room for freshly oxygenated blood to enter. But again, yawning stood out for its consistency and directionality. A differentiation that researchers said indicates that yawning plays its own unique “functional physiological purpose.”

Even contagious yawning—the reflexive urge to yawn when you see or hear someone else do it—appears to trigger measurable fluid shifts, particularly during the exhale phase. That overlap suggests the phenomenon may be more than just social mimicry and may actually carry a biological payoff.

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Theories on yawning have ranged from cooling the brain to increasing alertness. This new research adds another possibility: that yawning could be part of the brain’s routine housekeeping system—helping circulate fluids, clear waste, and maintain pressure balance.

The researchers suggested that the latest findings could open the door to future research explorations on the involuntary process.

“Yawning appears to be a highly adaptive behavior,” the study notes, “and further research into its physiological significance may prove fruitful.”

Tamilore OshikanluBreaking News Intern

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