Myth or Fact: We Swallow Spiders in Our Sleep

Common house spider on the floor in a home
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No matter what generation you grew up in, chances are you heard the rumor that we swallow a certain number of spiders each year as we sleep. However, the truth is that the chances of you swallowing a spider while sleeping are slim to none. 

Research Findings

Not a single study has been done to date to quantify the number of spiders people swallow while sleeping. Scientists do not give this topic a moment's glance, however, because it is nearly impossible. You can rest peacefully because the chances of swallowing a spider while you are asleep are almost none. The only reason they do not say the chances are zero is that nothing is impossible. In order for you to unknowingly swallow a spider in your sleep, a number of unlikely occurrences would all have to happen in sequence:

  1. First, you would have to be sleeping with your mouth wide open. If a spider crawled on your face and over your lips, you would likely feel it. So a spider would have to approach you by descending from the ceiling above you on a silk thread.
  2. Then, the spider would have to hit the target—your mouth—dead center to avoid tickling your lips. If it landed on your tongue, a highly-sensitive surface, you would feel it for sure.
  3. Next, the spider would have to land at the back of your throat without touching anything on the way in. Finally, at the very moment of landing on your throat, you would have to swallow.

This series of coincidences is highly unlikely. 

Spider Behavior

Spiders are not going to voluntarily approach the mouth of a large predator. Spiders view humans as a danger to their well-being. Sleeping humans are most likely viewed as terrifying.

A slumbering person breathes, has a beating heart and perhaps snores—all of which create vibrations that warn spiders of an imminent threat. We appear as big, warm-blooded, threatening creatures that might eat them on purpose.

We Do Eat Spiders—Just Not in Our Sleep

The rumor about swallowing spiders in your sleep may be debunked, but that does not mean that you do not eat spiders. Spider and insect parts make it into our food supply every day, and it is all FDA approved.

For example, according to the FDA, there is an average of 60 or more bug fragments per quarter pound of chocolate. Peanut butter has 30 or more insect fragments per quarter pound. Everything you eat likely has critter parts in it, but this is normal. It is fairly impossible to avoid having these mini body parts in our food. As it turns out, bits of arthropods in your food will not kill you and can make you stronger—protein and nutrient levels in some insects and arachnids can match that of chicken and fish.

Misleading Information on the Internet

To test a theory that people were susceptible to accepting anything they read online as true, Lisa Holst, a columnist for "PC Professional" in the 1990s conducted an experiment. Holst authored a list of fabricated facts and statistics including the old folkloric rumor that the average person swallows eight spiders per year. As Holst hypothesized, the statement was readily accepted as fact and went viral. 

Thanks to Holst, the younger generations now know the old fashioned rumor. It might have faded into the past if left in the past, but now, some still believe the rumor is true.