Why Do We Sleep Under Blankets?

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iStock

If you’re one of those people who sleeps with a sheet even on the hottest of nights, you’re not alone. Plenty of people can’t fall asleep if they aren’t covered with something, even if it’s the lightest of blankets. Why? Dan Nosowitz at Atlas Obscura reports that it’s both physiological and behavioral, and may have a component of simple conditioning.

Surprisingly, he found, sleeping with blankets is a relatively new phenomenon. Historically, blankets were expensive. Through the Middle Ages, Europeans only owned blankets if they were very wealthy. They were so precious, in fact, that bedding was passed down in people’s wills. Instead of snuggling up with a fluffy duvet, most people slept in the same bed as the rest of the household, farm animals included, to keep warm. But as fabric became cheaper and blankets more accessible, they became more commonplace household items. Now, even in tropical places, many people cover themselves with at least something during the night, with the exception of some nomadic cultures near the equator.

Part of the reason is that the body really does need extra warmth at night. Your body’s internal temperature begins to cool down before you go to bed. That’s one reason why some sleep experts recommend taking a bath or shower before bed, since your body will naturally cool off afterward, signaling to your body that it’s time to drift off. (Sticking one foot outside the covers can help, too.) Later in the night, though, that cooling off gets less pleasant and more, well, cold. During REM sleep, your body can’t regulate its own temperature. And for the most part, people tend to be in the REM stage of sleep right around dawn, when temperatures are the coldest. So we naturally learn that even if it’s pretty hot when we go to bed, we’ll wake up shivering at 4 a.m. if we don’t have a blanket.

And then there’s the neurological reason: Weighted blankets have been found to decrease anxiety and stress, because gentle pressure can stimulate serotonin production. Serotonin has been found to help modulate sleep regulation, which is part of the reason that depression and insomnia are linked—when you’re depressed, your serotonin levels are low.

There are more simple psychological reasons to cover up, too. When you’re a baby, your parents put blankets on you when you sleep, so you’re conditioned throughout your early years to associate blankies with bedtime. Above all, maybe we just all want to be swaddled forever. Doesn't that sound nice?

[h/t Atlas Obscura]

What Is the Shelf Life of Donated Eyes?

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iStock.com/Pedro_Turrini

Zoe-Anne Barcellos:

I can only answer for cornea and eye donation.

The FDA does all oversight (no pun intended) of organ disposition.

The main organs—heart, liver, pancreas, lungs, etc.—are transplanted within hours. They are just not viable if they are not being perfused constantly.

The other tissues—like bone, skin, tendons, etc.—do not need to be transplanted immediately. But I am not sure on the regulations of when they need to be transplanted.

With the eyes, there are four tissues that can be recovered.

We recover whole eyes for research and education purposes. These usually go much faster, but we can hold them up to a year.

Conjunctiva can also be recovered; conjunctiva is a clear covering over most of the eye (it is what gets irritated when you have pink eye). I have been working as a recovery tech for five years, and our office has not had a request for "conj" in all that time. I believe it is mostly used for research, but I could be wrong.

Sclera is the white area of your eye. It is fairly thick and flexible. If you have ever touched a reptile egg, that is what it reminds me of. We recover sclera for transplant. They use it for several things, but mainly to patch punctures. Similar to if you pop the inner tube of your bike and repair it. Sclera can also be used to repair ear drums. We can hold on to this for up to a year.

The main thing we recover is corneas. In the U.S., we must transplant these within seven days of recovery. (Recovery is usually within hours of death, but we can push it up to 20 hours after if needed.) Sometimes we have more corneas than we need, and then they are shipped overseas and transplanted up to 14 days after recovery. There is no real different outcome with the later transplant time, but the FDA in the U.S. made the rules. (You can sign up to be an organ, tissue, and eye donor here.)

This post originally appeared on Quora. Click here to view.

Why Are There No Snakes in Ireland?

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iStock

Legend tells of St. Patrick using the power of his faith to drive all of Ireland’s snakes into the sea. It’s an impressive image, but there’s no way it could have happened.

There never were any snakes in Ireland, partly for the same reason that there are no snakes in Hawaii, Iceland, New Zealand, Greenland, or Antarctica: the Emerald Isle is, well, an island.

Eightofnine via Wikimedia Commons // Public Domain

Once upon a time, Ireland was connected to a larger landmass. But that time was an ice age that kept the land far too chilly for cold-blooded reptiles. As the ice age ended around 10,000 years ago, glaciers melted, pouring even more cold water into the now-impassable expanse between Ireland and its neighbors.

Other animals, like wild boars, lynx, and brown bears, managed to make it across—as did a single reptile: the common lizard. Snakes, however, missed their chance.

The country’s serpent-free reputation has, somewhat perversely, turned snake ownership into a status symbol. There have been numerous reports of large pet snakes escaping or being released. As of yet, no species has managed to take hold in the wild—a small miracle in itself.

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