We all swallow eight spiders each year while we are sleeping. That’s a fact. It has to be, because it says so on the internet. Or maybe it isn’t a fact…. After all, the internet also says that rumor was started by a tongue-in-cheek article in a scientific magazine, and people have just accepted it as gospel. So which is it? And just how many spiders do we swallow each year?

For years, popular culture tells us that while we sleep, we annually ingest eight spiders. Rod Crawford, the arachnid curator at Seattle’s Burke Museum of Natural History and Culture, says, “Once or twice a year, someone tells me they once recovered a spider leg in their mouth.” Crawford receives these reports with a hefty dose of skepticism.

Of the three or four spider species in North America that tend to share a home with humans, none of them are particularly attracted to the human body. They tend to spend their waking hours tending their webs or hunting in nonhuman-infested areas. A bed inhabited by a human is unlikely to attract a spider’s interest. For one thing, the bed offers no prey for the spider, unless the bed or the person is infested with parasites. If that is the case, the least of that person’s worries are about spiders. In the second place, spiders have no interest in humans. “Spiders regard us much like they’d regard a big rock,” says Bill Shear, a biology professor at Hampden–Sydney College in Virginia and former president of the American Arachnological Society. “We’re so large that we’re really just part of the landscape.”

If humans are a part of the landscape, from a spider’s perspective, we are probably more akin to an active volcano. Spiders are hardwired to detect to vibrations. A sleeping human is a mega-vibration factory, producing heartbeats, snores, breathing, and movements. Vibrations of this magnitude scream, “DANGER!” to any nearby spider.

Human biology also works against ingesting spiders. If a sleeping person has his or her mouth open, it is probably because he or she is snoring. That would almost certainly scare off any would-be eight-legged invader. Additionally, the sensation of a spider crawling on one’s face is likely to awaken all but the most serious slumberers.

While it is biologically possible for a human to ingest a spider, such an occurrence would be a strictly random event. “People tell me this happened to them, but they threw it (the evidence) away—flushed it down the toilet, usually,” Crawford says. Given the absence of eyewitnesses to the phenomenon, it is not possible to accurately extrapolate that every person ingests eight spiders each year.

So how did that rumor start? If you do a little digging on in the internet, you will invariably come across the explanation that it all started as a tongue-in-cheek article about how people will believe anything. Snopes.com, the popular truth-checking website, joins in the claim that it all started with an article in PC Professional by columnist Lisa Holst. According to Snopes, Holst wrote a 1993 piece “Reading is Believing,” published on January 7, 1993. In this article she offered her own made-up list of ridiculous “facts,” that people will believe if they read them in an email. Among these “facts” was the claim that the average person swallows eight spiders per year.

There are just few things wrong about this analysis. In the first place, Lisa Holst didn’t write the article. In the second place, no article entitled “Reading is Believing” ever appeared in PC Professional Magazine. In the third place, there has never been a PC Professional Magazine.

In other words, the origin of the urban legend is, itself, an urban legend.

Hopefully, all of us will now sleep a little more soundly at night, less concerned about what we might ingest while we slumber. If there are any spiders reading this, they can relax, as well. For all we know, young spiders have nightmares, triggered by breathless reports of the nighttime disappearances of all the spiders who wander too close to the arachnid-devouring Homo sapiens.

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