Olivia: Maybe you tried this as a kid: challenging your friends on the playground to see how long everyone could hang upside down from the monkey bars. You could feel the blood rushing to your head, and maybe you lasted a few minutes before giving up, because it’s pretty uncomfortable. Or maybe an adult told you to get down because your head will explode, or something silly like that.

Well, it turns out that hanging upside down isn’t all fun and games. Because if you do it for too long, like a few hours or more, you actually could die.

Now, it’s not a common thing. Most of the reported cases involve people getting trapped upside down somehow, like a man in Utah who got stuck in a cave and died after 28 hours. Medical examiners call these deaths in a head-down position, reverse or inverse suspension. The exact reason why hanging upside down can kill you isn’t totally clear, because there are a lot of things that could go wrong.

In a lot of these cases, the official cause of death is asphyxiation, or a lack of oxygen. Physicians have proposed that when you’re upside down, your liver and intestines put extra weight onto your lungs, making it harder to breathe. But others think heart failure is usually to blame.

If you’re flipped around, there’s a lot more blood flowing toward your heart than normal, and that makes it harder for your heart to pump it back out. Eventually, your heart isn’t able to pump enough blood to keep your body going, which is what we call heart failure.

If being upside down increases stress on your heart, that could also explain why it seems to take less time for older people or people with heart conditions to die in these unfortunate situations.

Then, there’s all that blood in your brain, increasing pressure. And that could rupture a blood vessel and trigger a brain hemorrhage, damaging brain cells. But strangely, forensic scientists haven’t seen a lot of brain bleeding in upside-down deaths.

Even if you don’t die, hanging upside down could still be dangerous for your eyes. Your eye is just a squishy orb filled with fluid, which focuses light onto your retina so you can see. And things can go wrong if that fluid is at the wrong pressure.

When you’re upside down, the pressure inside your eye can double, and a few people have reported temporary vision problems. So, it’s probably best to stop those kinds of playground challenges... and just, y’know, avoid death-defying stunts that involve hanging upside down. They’re pretty dangerous.

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