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Over the course of your life time, the average person eats X spider/insects/whatever whilst they are sleeping.

X tends to vary according to who you ask. Is this just an urban legend?

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Zero is a number... –  fred Apr 8 '11 at 13:25
A spider scientist once told me that there is [almost] always a spider within 8 feet of you. –  JD Isaacks Apr 8 '11 at 17:31
@John: Or was it that there is always a spider with all 8 feet in you? –  Potatoswatter Apr 8 '11 at 19:10
I liked the old Dave Barry bit, which was to point out that the 8 spiders a year was an average, and because nobody he knew ate any spiders, it must mean that someone, possibly Donald Trump, was eating millions of spiders to get the average up. –  Scott Hamilton Apr 12 '11 at 16:14
What happens if you eat one while awake, and then it crawls out of you...? Is that eating -1 insects while sleeping? –  muntoo May 12 '11 at 0:31
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4 Answers

up vote 32 down vote accepted

This is an utter fabrication. In fact, it started with an article in PC Professional Magazine regarding ridiculous facts circulating via e-mail.

In a 1993 PC Professional article, columnist Lisa Holst wrote about the ubiquitous lists of "facts" that were circulating via e-mail and how readily they were accepted as truthful by gullible recipients. To demonstrate her point, Holst offered her own made-up list of equally ridiculous "facts," among which was the statistic cited above about the average person's swallowing eight spiders per year, which she took from a collection of common misbeliefs printed in a 1954 book on insect folklore. In a delicious irony, Holst's propagation of this false "fact" has spurred it into becoming one of the most widely-circulated bits of misinformation to be found on the Internet.

From Snopes.com

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interestingly, citing Lisa Holst and her PC Professional article as the source of the myth has become a bit of a myth itself: eightspiders.com/2008/08/why-eight-spiders.html –  Oliver_C Apr 8 '11 at 15:39
Hmmm...so one person couldn't find a an article written 15 years ago (before everything went online). And Lisa Holst must be a fairly common name. –  ElendilTheTall Apr 8 '11 at 16:05
well, apparently even the Library of Congress doesn't know about a "PC Professional Magazine" (the book from 1954 however does exist). Is there any other website that mentions Lisa Holst's article without copying/referencing Snopes? Is this article mentioned anywhere else, maybe in another context (after all it wasn't just about spiders)? –  Oliver_C Apr 8 '11 at 18:07
There is now a question regarding the Lisa Holtz source. –  Jason Plank Apr 13 '11 at 23:45
Seriously, I can confirm that there was (maybe still is) a PC magazine called "PC Professionell" ending in the german (latin?) suffix ~ell, not ~al. Here is an ebay auction with a 1991 magazin Here is a press artigcle from 2001. –  user unknown May 14 '12 at 5:19
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From Rod Crawford (Curator of Arachnids, Burke Museum)

For a sleeping person to swallow even one live spider would involve so many highly unlikely circumstances that for practical purposes we can rule out the possibility. No such case is on formal record anywhere in scientific or medical literature.

[...] I remain unconvinced that a spider would visit a huge breathing monster and enter its mouth.

Unless a spider is so small that it wouldn't realize that the "hole" is the mouth of a large predator, it's probably unlikely that a spider would crawl into it.

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I invoke "The theory of large numbers", given enough opportunity even very unlikely events occur in significant numbers. However, as it is probable that someone has in their lifetime swallowed a spider in their sleep, it is still unlikely that on average a human will swallow > 1 spider. –  rjstelling Apr 8 '11 at 14:11
Spiders (and various other invertebrates) can detect high concentrations of carbon dioxide and avoid it, presumably to avoid mouths (and even the skin of large creatures that may crush them accidentally). So spiders, no matter how small, do realize that mouths, no matter how big, are to be avoided. (Incidentally, mosquitos use these CO2 sensors in reverse--instead of running away, they run towards....) –  Rex Kerr Apr 8 '11 at 23:35
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The Straight Dope claims that one person may accidentally swallow a large number of spiders after an egg sac bursts:

Put it all together, and it would be a miracle for a spider to end up in anyone's mouth while they're sleeping, except for one rare circumstance--when a spider egg sac hatches indoors. At that point, you can have hundreds of microscopic spiders, a millimeter long or less, leaping into the air in a short time span (under an hour total) and trying to ride the air currents to freedom.

However, these events should be rare and the author argues that average number of spiders swallowed being so high seems doubtful:

After all, most people breathe while they sleep (at least I do) and spiders, like virtually all arthropods, flee from breath. After all, there are lots of vertebrates that EAT arthropods, and if you're an arthropod and something is breathing on you, it's not a good idea to stick around. Simple enough.

So, it seems unlikely, but the arguments given in this particular article aren't conclusive.

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Strangely I have woken up with a spider in my mouth once... I woke up, shut my mouth and felt something wriggle, freaked and spat out a slightly squished house spider.

Now I would not suggest that this is a regular occurance, the house I was staying in at the time was quite old and covered in dust and cobwebs and we generally keep our houses much cleaner nowadays than the older generations ever did. I would suggest the spider somehow managed to accidently fall into my mouth and it woke me up in its attempts to get out.

However based on this experience I would say it is not impossible for us to accidently eat a spider in our sleep, however it would be extremely unlikly.

People generally tend to wake up to strange noises or motions (e.g. crashing around downstairs, earthquake, etc) which is most likely due to our bodies trying to protect us in the case of the unexpected. I'm sure most people have been tired or had a few drinks but suddenly been put in a dangerous or unexpected situation and our bodies had instantly sobered us up, or woken us up. Having an unexpected arachnid fall in your mouth and start wriggling around would probably trigger your survival instinct and wake you up (as it did for me).

This is speculation, but I would think that the majority of people would wake up if something fell/crawled into thier mouth and know if they had eaten a spider.

In summary I would suggest eating a spider in your sleep once during your lifetime is plausible, but I doub't there are any studies to prove it.

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I wait for someone to say "ewwwwww....." –  muntoo May 12 '11 at 0:33
This isn't a full referenced answer, but more of an opinion. Please add some references or delete. –  Oddthinking May 3 '12 at 5:10
This was answered a year ago, and you only now get around to saying this? –  Ardesco May 3 '12 at 14:50
@Ardesco the reason for bringing it up now is that we're trying to do a cleanup :) –  jozzas Jul 27 '12 at 5:31
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