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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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Beyond the Label: How to Pick the Right Medicines For Your Cold and Flu Symptoms
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The average household spends an annual total of $338 on various over-the-counter medicines, with consumers making around 26 pharmacy runs each year, according to 2015 data from the Consumer Healthcare Products Association. To save cash and minimize effort (here's why you'd rather be sleeping), the Cleveland Clinic recommends avoiding certain cold and flu products, and selecting products containing specific active ingredients.

Since medicine labels can be confusing (lots of people likely can’t remember—let alone spell—words like cetirizine, benzocaine, or dextromethorphan), the famous hospital created an interactive infographic to help patients select the right product for them. Click on your symptom, and you’ll see ingredients that have been clinically proven to relieve runny or stuffy noses, fevers, aches, and coughs. Since every medicine is different, you’ll also receive safety tips regarding dosage levels, side effects, and the average duration of effectiveness.

Next time you get sick, keep an eye out for these suggested elements while comparing products at the pharmacy. In the meantime, a few pro tips: To avoid annoying side effects, steer clear of multi-symptom products if you think just one ingredient will do it for you. And while you’re at it, avoid nasal sprays with phenylephrine and cough syrups with guaifenesin, as experts say they may not actually work. Cold and flu season is always annoying—but it shouldn’t be expensive to boot.

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Why You Might Not Want to Order Tea or Coffee On Your Next Flight
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A cup of tea or coffee at 40,000 feet may sound like a great way to give yourself an extra energy boost during a tiring trip, but it might be healthier to nap away your fatigue—or at least wait until hitting ground to indulge in a caffeine fix. Because, in addition to being tepid and watery, plane brew could be teeming with germs and other harmful life forms, according to Business Insider.

Multiple studies and investigations have taken a closer look at airplane tap water, and the results aren’t pretty—or appetizing. In 2002, The Wall Street Journal conducted a study that looked at water samples taken from 14 different flights from 10 different airlines. Reporters discovered “a long list of microscopic life you don’t want to drink, from Salmonella and Staphylococcus to tiny insect eggs," they wrote.

And they added, "Worse, contamination was the rule, not the exception: Almost all of the bacteria levels were tens, sometimes hundreds, of times above U.S. government limits."

A 2004 study by the U.S. Environmental Protection Agency (EPA) found that water supplies on 15 percent of 327 national and international commercial aircrafts were contaminated to varying degrees [PDF]. This all led up to the 2011 Aircraft Drinking Water Rule, an EPA initiative to make airlines clean up. But in 2013, an NBC investigation found that at least one out of every 10 commercial U.S. airplanes still had issues with water contamination.

Find out how airplane water gets so gross, and why turning water into coffee or tea isn’t enough to kill residual germs by watching Business Insider’s video below.

[h/t Business Insider]

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