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iStockPhoto

Why Does Sex Make Men Sleepy?

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iStockPhoto

Alfred Kinsey, biologist, pioneering sex researcher and founder of the Institute for Sex Research at Indiana University*, once wrote that "a marked quiescence of the total body is the most widely recognized outcome of orgasm," more noticeably among males. Why is that?

Let's get the obvious reasons out of the way first. Sex often, though not always, happens at night in a bed and is physically exhausting. If you're tired to begin with, all that physical exertion only adds to it, and since you're already in bed, it's only natural to be sleepy. Compounding this is the fact that sex dominates your attention when you're having it (and sometimes when you're not), so you don't pay attention to your breathing and wind up breathing shallowly and holding your breath pretty often. These aren't really the sorts of things you want to do during vigorous exercise, as they lead to oxygen deprivation and—all together now—sleepiness.

There's also the biochemistry of the orgasm to consider.

After sex, a man's brain releases a slew of hormones and neurotransmitters. Some of them, like prolactin, oxytocin and vasopressin, have been linked to sleep as well as sex. Prolactin plays a role in sexual satisfaction by counteracting the effects of dopamine** (which is responsible for sexual arousal). It's also been shown that the artificial delaying of an REM sleep period disrupts the rhythm of prolactin release, and that REM sleep is reduced in mice with prolactin deficiencies. Oxytocin and vasopressin have also both been implicated in the body's regulation of sleep cycles. While none of these chemicals are fully understood and their links to sleep aren't concrete, the circumstantial evidence suggests that they may play a part in pulling you off to a post-coital snooze.

What About the Ladies?

The phenomena of men falling asleep soon after sex is a little more well established than women doing the same—at least in that people notice it enough to make jokes about it on sitcoms, and write in to mental_floss asking about it. While I haven't been able to find any science-backed evidence that post-sex sleepiness definitively affects men more than women, there are a few hypotheses floating around as to why it seems that way. In their 2006 book Why Do Men Fall Asleep After Sex?, Mark Leyner and Billy Goldberg, M.D. suggest that exertion during sex depletes the muscles of energy-producing glycogen. Because men usually have more muscle mass, they get more tired. And it's entirely possible that women get just as sleepy, just as fast as men do after orgasm, but women simply have orgasms during sex less often than men do.

*Kinsey left his mark on a different field earlier in his career: entomology. He did his doctoral thesis on gall wasps and researched and published papers about them at the American Museum of Natural History in New York. Of the 18 million+ insects in the museum's collections, about 5 million are gall wasps that Kinsey collected. In return for his collection, Kinsey received $400 and a lifetime membership to the Museum.

**The hormone may also mediate the "sexual refractory period," or the recovery phase after an orgasm during which a man cannot have additional orgasms or achieve an erection.

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'Lime Disease' Could Give You a Nasty Rash This Summer
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iStock

A cold Corona or virgin margarita is best enjoyed by the pool, but watch where you’re squeezing those limes. As Slate illustrates in a new video, there’s a lesser-known “lime disease,” and it can give you a nasty skin rash if you’re not careful.

When lime juice comes into contact with your skin and is then exposed to UV rays, it can cause a chemical reaction that results in phytophotodermatitis. It looks a little like a poison ivy reaction or sun poisoning, and some of the symptoms include redness, blistering, and inflammation. It’s the same reaction caused by a corrosive sap on the giant hogweed, an invasive weed that’s spreading throughout the U.S.

"Lime disease" may sound random, but it’s a lot more common than you might think. Dermatologist Barry D. Goldman tells Slate he sees cases of the skin condition almost daily in the summer. Some people have even reported receiving second-degree burns as a result of the citric acid from lime juice. According to the Mayo Clinic, the chemical that causes phytophotodermatitis can also be found in wild parsnip, wild dill, wild parsley, buttercups, and other citrus fruits.

To play it safe, keep your limes confined to the great indoors or wash your hands with soap after handling the fruit. You can learn more about phytophotodermatitis by checking out Slate’s video below.

[h/t Slate]

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Lia
Lia Is a Disposable Pregnancy Test You Can Flush Down the Toilet
Lia
Lia

It’s a common Hollywood plot point: A character spots a discarded pregnancy test in a bathroom trash can. Surprise! Someone’s pregnancy is revealed, though they weren’t yet ready to tell anyone (and perhaps never planned on telling them at all). Lia is a new type of disposable pregnancy test designed to be flushed down the toilet to make sure no one ever experiences that kind of privacy violation, according to Glamour.

Lia hasn’t hit the market yet, but when it does, it will be the first major redesign of the home pregnancy test in decades. The first at-home pregnancy test in the U.S. debuted in 1977, and while it took two hours to show a result, it gave women the option to learn their pregnancy status with relative accuracy (it was 97 percent accurate for positive results, but only 80 percent accurate for negative results) for the first time without going to the doctor. In 1988, Unilever came out with the first wand-style pregnancy test—the plastic kind you pee on to reveal the blue stripe indicators. Since then, not much has changed about the basic design of the at-home pregnancy test except the graphics that companies use to convey the test’s results. (The science undergirding the tests has advanced over the years, though.)

Unlike the plastic sticks, Lia is disposable and can be flushed down the toilet or composted. With the shape reminiscent of a sanitary pad, it works similar to the traditional pee-stick test: You urinate on it, then wait for the stripes to appear. While it’s water-resistant enough to withstand the two minutes of pee-soaking required to get a result, the test strip is made of the type of plant fibers that go into toilet paper and will eventually disintegrate in water. It can also be composted: In one experiment, it took 10 weeks to completely degrade in soil.

A diagram of Lia's features
Lia

Like other pregnancy tests available at the drug store, Lia’s results are based on the concentration of human chorionic gonadotropin (a pregnancy hormone) in your pee. It’s FDA approved, and the company reports that it’s more than 99 percent accurate, comparable to other tests on the market.

No matter what the circumstances surrounding a pregnancy are, most people don’t want to share the fact that they could be pregnant with everyone they might share a bathroom with—most people wait several months into their pregnancy to announce the news—and even if they want to tell the world immediately, they probably don’t want to do so via trash can. Lia’s paper design makes it easy to dispose of the test without worrying about who might stumble upon your wastebasket. It’s also more sustainable and won’t clog up landfills like plastic tests. While people don’t use as many pregnancy tests as, say, plastic straws, the over-the-counter plastic pregnancy test market is still a huge one, and a contributor to environmental pollution. As a bonus, the lack of plastic makes Lia cheaper to produce, too.

Lia will eventually be available in stores and online. It’s scheduled to be released sometime in 2018.

[h/t Glamour]

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