Do You Swallow Spiders in Your Sleep? The Myth Debunked

Where does the “eight spiders a year” claim come from?

The idea that we swallow a certain number of spiders while asleep, most often quoted as eight a year, began spreading widely in the 1990s through chain emails, magazine filler items and later websites listing “amazing facts”. It has never been traced to a real study, survey or medical report.

A popular story says that in 1993 a magazine columnist made the statistic up on purpose, to show how readily people believe facts they read online. That explanation has itself been repeated many times, but no one has found the original column, and the author named in the story has never been confirmed to exist. In other words, even the debunking of the myth may be a myth. What is clear is that no researcher has ever measured spiders swallowed by sleeping people.

Why spiders avoid sleeping people

Spiders sense the world mainly through vibrations, touch and chemical cues, and to them a sleeping person is a noisy, dangerous place:

• Vibrations. Breathing, a beating heart and small movements make constant vibrations that spiders feel through their legs. For a spider, vibrations usually signal a predator or a large animal.
• Breath. Air flowing in and out of the mouth and nose is warm, moist and contains carbon dioxide, a strong signal that a large animal is near.
• Heat. Most spiders hunting indoors are looking for insects in cool, quiet corners, not warm skin.
• No reason to go there. A mouth offers a spider no food or shelter, and spiders do not wander about randomly looking for holes to climb into.

Arachnologists such as Rod Crawford of the Burke Museum in Seattle have long pointed out that a spider entering a sleeping person’s mouth would be an extremely rare accident, not a regular event. A person would also be likely to wake up if anything crawled across their lips or tongue.

Do spiders crawl into beds at all?

Sometimes, by chance. Wandering spiders, especially the adult male house spiders that roam indoors in late summer and fall, may cross a bed while searching for females. That is part of the life cycle explained in Why do spiders come indoors in the fall?.

Most indoor spiders, though, stay in or near their webs in corners, behind furniture or in cellars. Long-legged cellar spiders, like the one in the photo, spend their lives hanging upside down in loose webs near ceilings. The giant house spider waits in a funnel web at floor level and rarely leaves it except to mate.

Could a spider in bed bite you?

It is possible but unusual. Spiders bite people mainly when they are trapped against the skin, for example if someone rolls onto them. House spiders in Europe and North America are harmless, and many cannot pierce human skin at all.

Many marks that people find in the morning and blame on spiders are actually bites from bedbugs, fleas or mosquitoes, or skin problems that have nothing to do with insects. Doctors stress that a “spider bite” can only be confirmed if the spider was seen biting. For more detail, see Are house spiders dangerous?.

Why do myths like this spread?

The swallowed-spider claim has the ingredients of a memorable myth. It sounds precise, it involves something that happens while we cannot watch, and it plays on a common fear of spiders. Because no one can easily check what happens in their own sleep, the statement is hard to disprove from personal experience.

It also rides on real facts. Spiders really do live in almost every home, often in large numbers, and people really do sometimes find a spider in bed. The myth simply takes these true observations and adds a dramatic, made-up number.

Other common spider myths

Many of these ideas are easy to remember and spread quickly, but they do not hold up when compared with what is known about spider biology. For more about how and what spiders really eat, see What do spiders eat?.