Holding your breath may be more than just a good party trick.
While it sounds like the last thing you’d want to do to your brain, new research suggests that regularly depriving it of oxygen could come with some surprising benefits.
The study authors say their findings could one day pave the way for a new kind of brain training designed to make the vital organ more resilient.
To investigate, the researchers turned to the world of freediving, where people plunge underwater and stay submerged on a single breath without an air tank or other equipment.
Most people can hold their breath for somewhere between 30 and 90 seconds. Experienced freedivers, however, spend years training their bodies and minds to resist the urge to breathe, allowing them to remain underwater for several minutes at a time.
But the sport’s top performers can go far longer. Last year, Croatian freediver Vitomir Maričić set a Guinness World Record by voluntarily holding his breath underwater for a staggering 29 minutes and 3 seconds.
For most people, going that long without oxygen would be a medical emergency known as hypoxia.
The brain is especially vulnerable when oxygen runs low. Within minutes, neurons can start dying, while the nervous system struggles to send the signals needed to breathe, move, speak and see, according to the Cleveland Clinic.
Oxygen deprivation can cause symptoms like dizziness and trouble concentrating at first, then progress to problems such as confusion, drowsiness and seizures. If it lasts too long, it can cause permanent brain damage or death.
And yet, something unexpected appears to be happening inside the brains of freedivers.
Despite repeatedly pushing their brains into low-oxygen states, studies have found that these athletes don’t show the cognitive problems typically linked to hypoxia. They also show no signs of obvious structural damage to their hippocampi, a vulnerable area of the brain that plays a key role in memory and navigation.
To find out why, researchers recruited 17 experienced recreational freedivers — all men between 27 and 55 — for seven months of standardized training.
They also recruited 20 men of similar ages and backgrounds who didn’t freedive. The control group was still physically active, engaging in about five hours of aerobic exercise a week.
Before and after the training, the freedivers underwent brain scans while they were breathing normally and while they were holding their breath to see how different parts of the brain communicated with one another.
The participants took memory tests, too. They were shown pairs of locations and hand gestures, then asked 15 minutes later to identify the exact combinations they had seen from similar and completely new ones.
The goal was to see whether any brain changes linked to freediving were also tied to how well the divers remembered things.
After seven months, the divers’ brain scans showed changes in how different regions communicated, including areas involved in attention, decision-making, movement and sensory processing.
The hippocampus stood out in particular.
Both sides formed stronger connections with the cerebellum, a part of the brain best known for coordinating movement, but also linked to memory and other thinking skills. At the same time, the hippocampus became less connected to areas involved in movement and sensory processing, especially when the divers were breathing normally.
Researchers think the brain may have been shifting its focus away from outside stimuli and toward internal processes that help preserve memory during the extreme conditions of freediving.
When it came to the memory tests, divers with stronger connections between the left hippocampus and cerebellum tended to be better at telling similar memories apart and recognizing new ones.
Those with weaker connections between the right hippocampus and movement and sensory areas tended to be better at recognizing memories they had seen before.
The research suggests that repeated exposure to low oxygen may change how the hippocampus communicates with the rest of the brain — potentially helping freedivers maintain their memory despite the extreme conditions.
The study authors said that their findings could eventually help scientists develop treatments that use carefully controlled periods of low oxygen to help the brain adapt and become more resilient, potentially offering new approaches for conditions linked to aging, brain degeneration or oxygen deprivation.
But that doesn’t mean you should go out and start holding your breath for minutes at a time.
The study was small, and while the freedivers were scanned before and after training, the control group was scanned only once. That means researchers can’t say for sure that freediving itself caused the brain changes.
And freediving can be dangerous, with the risks increasing as divers go deeper and without proper training and safety precautions.
