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Medical myths: We swallow 8 spiders a year in our sleep

Medical myths: We swallow 8 spiders a year in our sleep

Know your medical facts from myths? There are a lot of old wives' tales out there. But where do they come from and what is the truth? This week, do we really swallow spiders while we're asleep?

What's the truth? 

Logical reasoning helps with this one. Most people move while they're asleep and that would scare spiders. Most people don't sleep with their mouth open—and even those who do, tend not to swallow if something enters it.

You can test this by putting your finger in someone's mouth as they sleep. They're far more likely to wake up and ask what on earth you're doing than try to swallow it. Also, spiders tend to avoid open mouths—if they didn't, evolution would have made sure they became extinct, instead of one of the most successful groups of animals on the planet.


Where did the myth come from?

Spider's swallowed in sleep

It's thought that it was first mentioned in a book on insect and spider folklore in 1954. Then in 1993, a journalist called Lisa Holst wrote an article about the urban myths circulating in the early days of email and quoted this entirely false statistic as an example of how gullible people were.

The result was that people began quoting her article as the source of the "fact", despite Holst so clearly saying that it was untrue.


So there's nothing to worry about?

Theoretically, a spider could drop into your mouth if it was hanging from the ceiling.

But the chances that this would happen just as you opened your mouth and were about to swallow is so infinitesimally small as to not be worth worrying about.