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Why Does Sex Make Men Sleepy?

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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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Medicine
New Cancer-Fighting Nanobots Can Track Down Tumors and Cut Off Their Blood Supply
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Scientists have developed a new way to cut off the blood flow to cancerous tumors, causing them to eventually shrivel up and die. As Business Insider reports, the new treatment uses a design inspired by origami to infiltrate crucial blood vessels while leaving the rest of the body unharmed.

A team of molecular chemists from Arizona State University and the Chinese Academy of Sciences describe their method in the journal Nature Biotechnology. First, they constructed robots that are 1000 times smaller than a human hair from strands of DNA. These tiny devices contain enzymes called thrombin that encourage blood clotting, and they're rolled up tightly enough to keep the substance contained.

Next, researchers injected the robots into the bloodstreams of mice and small pigs sick with different types of cancer. The DNA sought the tumor in the body while leaving healthy cells alone. The robot knew when it reached the tumor and responded by unfurling and releasing the thrombin into the blood vessel that fed it. A clot started to form, eventually blocking off the tumor's blood supply and causing the cancerous tissues to die.

The treatment has been tested on dozen of animals with breast, lung, skin, and ovarian cancers. In mice, the average life expectancy doubled, and in three of the skin cancer cases tumors regressed completely.

Researchers are optimistic about the therapy's effectiveness on cancers throughout the body. There's not much variation between the blood vessels that supply tumors, whether they're in an ovary in or a prostate. So if triggering a blood clot causes one type of tumor to waste away, the same method holds promise for other cancers.

But before the scientists think too far ahead, they'll need to test the treatments on human patients. Nanobots have been an appealing cancer-fighting option to researchers for years. If effective, the machines can target cancer at the microscopic level without causing harm to healthy cells. But if something goes wrong, the bots could end up attacking the wrong tissue and leave the patient worse off. Study co-author Hao Yan believes this latest method may be the one that gets it right. He said in a statement, "I think we are much closer to real, practical medical applications of the technology."

[h/t Business Insider]

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Medicine
New Peanut Allergy Patch Could Be Coming to Pharmacies This Year
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About 6 million people in the U.S. and Europe have severe peanut allergies, including more than 2 million children. Now, French biotechnology company DBV Technologies SA has secured an FDA review for its peanut allergy patch, Bloomberg reports.

If approved, the company aims to start selling the Viaskin patch to children afflicted with peanut allergies in the second half of 2018. The FDA's decision comes in spite of the patch's disappointing study results last year, which found the product to be less effective than DBV hoped (though it did receive high marks for safety). The FDA has also granted Viaskin breakthrough-therapy and fast-track designations, which means a faster review process.

DBV's potentially life-saving product is a small disc that is placed on the arm or between the shoulder blades. It works like a vaccine, exposing the wearer's immune system to micro-doses of peanut protein to increase tolerance. It's intended to reduce the chances of having a severe allergic reaction to accidental exposure.

The patch might have competition: Aimmune Therapeutics Inc., which specializes in food allergy treatments, and the drug company Regeneron Pharmaceuticals Inc. are working together to develop a cure for peanut allergies.

[h/t Bloomberg]

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