Understanding the Science Behind Holding Your Breath
From childhood contests to grown-up moments of poolside bravado, most of us have tested our limits to see how long we can go without breathing. The aftermath includes experiencing a little breathlessness, maybe some lightheadedness too, but nothing too serious. Right? Not quite. What happens when you hold your breath goes far beyond that quick dizzy spell. From plummeting oxygen levels to unexpected effects on your brain and body, there’s a lot going on when you hold your breath.
Science says there’s only so long we can go without a good gulp of air, and it depends on things like age, fitness, and lung power. Sure, some people take it to the extreme. But even with record-breaking training, your body still feels the impact. Curious about what happens when you hold your breath? Read on as we take a deep dive into the surprising science behind it.
Is It Safe to Hold Your Breath?
It depends. Most of us have tried breath-holding, whether at yoga class or while swimming laps, but it’s only safe when it’s done with proper technique and training. Competitors and professional divers train rigorously over extended periods of time. By taking deep breaths before submerging themselves, and also performing various other fitness exercises, a diver is able to push the carbon dioxide out of their body, which takes away the body’s natural reaction to come up for air.
But even with all the training in the world, how long is it actually safe to do so? We’ve got the answer for you ahead.
How Long Can Humans Hold Their Breath?
Unlike loggerhead sea turtles, who can go without air for up to 10 hours, most healthy human adults can comfortably hold their breath for 30 to 90 seconds. Anything beyond this is dangerous and should be avoided, as it can put you at risk for drowning—even in shallow water. But that’s not the only risk. Coming up: What’s going on within your body when you hold your breath.
What Happens When You Hold Your Breath?
By now, we know there’s only so long the human body can go without air. And whether you’re trained or not, pushing past that limit sets off a chain reaction in your body as it copes with the lack of oxygen. Here’s exactly what happens when you hold your breath for too long:
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Oxygen levels drop: Without fresh oxygen coming into our bodies, the oxygen saturation level of our blood goes down. This means that our brain and organs do not receive the oxygen they need to function, a condition called hypoxia. When our brains begin to become hypoxic, the first symptoms are a feeling of confusion, altered decision-making, and loss of coordination.
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Carbon dioxide levels rise: Our bodies release carbon dioxide (CO2) when we exhale, so when we hold our breath, CO2 builds up and we get the urge to take another breath. However, this increase in carbon dioxide doesn’t always happen underwater.
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Risk of brain damage goes up: A study found that when divers held their breath for extended periods of time, they had higher levels of the protein S100B in their bloodstream. This protein is a marker for brain damage; fortunately, the increased level was temporary and went back to normal once they started breathing again.
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Coordination is affected: That same study also found that divers had higher levels of lactate (an ionized form of lactic acid) in their blood while holding their breath. Lactic acid is what builds up in your muscles during a long run or intense workout, and it can lead to cramping, soreness, and loss of coordination.
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Blood sugar levels rise: Holding your breath for too long can cause your blood sugar to jump. In the same study, researchers also found that blood glucose levels were higher in divers when holding their breath.
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Heart rate slows down: When our bodies are deprived of oxygen, the heart can’t pump fresh, oxygenated blood out to the body. Studies show that about 30 seconds of breath-holding can lead to a lowered heart rate and lower cardiac output.
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Blood pressure goes up: Once your body’s heart rate goes down during breath-holding, it tries to compensate by raising your blood pressure to get blood pumped to the body. It happens as our blood vessels constrict.
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Risk of passing out increases: The most dangerous risk of holding your breath underwater is the possibility of passing out in the water. When children hold their breath underwater, the pressure in their chests causes their blood vessels to cut off blood flow to the right side of the heart. As this happens, the heart can’t pump blood, which leads to the fainting reflex.
Should You Hold Your Breath for Extended Periods of Time?
Because of the very real risks involved—including accidental drownings among healthy kids and adults—the Centers for Disease Control and Prevention advises against practicing voluntary apnea altogether. So yes, breath-holding games are a no-go. But if you’ve got dreams about going toe-to-toe with record holders, it’s best to train with professionals under strict medical supervision. Safety first, bragging rights later!