Life is full of mysteries. Small mysteries, big mysteries, insignificant mysteries — they’re the in-betweens that surprise and impress almost daily, even if we don’t know why.

There’s a good chance we’ll never know what the conspicuous silhouette and blurry snapshots are of the Loch Ness Monster or Bigfoot. That said, pulling back the curtain to reveal everyday mysteries is less challenging while still being as complex and intriguing.

Here’s a quick look at four everyday mysteries and the explanation behind them.

Why a room looks dark after coming in from outside

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The human eye is a design masterpiece — a physiological marvel. It adjusts to focus, it adjusts to filter in light, and it adjusts so the outside world doesn’t do any damage. Part of this adjusting is done when you step from a bright, outside environment into a darker, indoor environment. It usually takes some time to adapt when you come inside from outside, and your vision can be dark and blurry.

Your eye is made of cones and rods that are meant to help detect light in different situations (daylight, starlight, etc.). Cones are responsible for light detection in the daylight, and rods are responsible for light detection in darkness. When you transition from daylight to darkness, those cones and rods adjust and keep adjusting to give your eye the optimum light reception it needs to see well. This adjustment doesn’t happen instantly, which is why your vision is a bit wonky when you come inside after being outside.

Would you believe that it can take anywhere from 20 to 30 minutes of “dark adaptation” for your eyes to fully adjust to a dark environment after you’ve been in the sun?

Why people say “God bless you” after someone sneezes

Photo of a person sneezing
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Your natural reaction when someone in the vicinity sneezes may be to exclaim, “God bless you,” but why is that the case? Why do people say that after a sneeze?

The answer is simple: to protect against the plague or to keep your soul from flying out your throat.

Sneezing used to be seen by the Greeks and Romans as a sign of good health, so they’d say “bless you” for your health, but public opinion and the Roman Catholics of the 14th century were saying “bless you” to ward off plague. Similar religious crowds thought that when you sneezed, the devil could reach in and steal your soul, or that your soul would fly away when you sneezed. Saying “bless you” kept it in.

Why you get goosebumps

Photo of goosebumps on skin
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People used to think that getting goosebumps made your body hair grow faster, but that’s not true.

The real reason why you get goosebumps — those little prickles all over your skin when a strange sensation washes over you, you get scared, or you feel a chill — is because the little muscle under each hair follicle contracts and causes the hair to stand up. What makes the muscle contract? Goosebumps are an involuntary reaction to stimuli like hormone surges or changes in temperature.

Goosebumps have no underlying survival correlation for humans. Humans don’t have enough hair to raise through goosebumps to make us look bigger or to keep us warmer during the cold (which is why scientists believe animals get goosebumps). The truth is, goosebumps are just all your little follicle muscles getting a reactive workout.

Why you get pins and needles in a limb when it falls asleep

Photo of people sitting in chairs with their legs crossed
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You feel like pins and needles are being poked up and down your limbs when they “go to sleep” after you’ve slept on them wrong or have been sitting awkwardly for a while. It’s normal, but it’s also kind of weird.

The reason we get pins and needles (the technical term is “paresthesia”) has to do with our nervous system and the way it reacts to pressure. The BBC summarizes paresthesia sensations by saying:

There are nerves throughout your body, biological superhighways whose job is to relay information between the brain and the rest of the body. If you place too much pressure on one of your arms or legs … you could temporarily pinch the nerves that run through them. Meanwhile, you’re also putting a little too much pressure on the blood vessels that supply those nerves, like crimping a garden hose to prevent the flow of water.

The pins and needles you feel is the response to blood rushing back into those temporarily pinched and oxygen-deprived areas, which causes your nerves to start firing to the brain like crazy.

Everyday mysteries often have simple scientific answers

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There’s a good chance you’ll find simple, scientific explanations for many of life’s everyday mysteries. The body, especially, reacts in strange and fascinating ways to various stimuli. Those reactions can make you wonder what’s happening and why things are a little askew, but most of these mysteries are nothing to lose sleep over. Do a little digging, and you’re bound to find a fun answer to any perplexing everyday mystery.