You Do Not Swallow Eight Spiders a Year in Your Sleep. That Claim Is a Myth.

The answer comes first: no, you do not swallow eight spiders a year in your sleep. There is no study behind the number, and no documented case behind the claim.

Scientific American put the point plainly. The myth flies in the face of both spider and human biology, which makes it highly unlikely that a spider would ever end up in your mouth. The Burke Museum in Seattle, home to arachnid curator Rod Crawford, goes further. For a sleeping person to swallow even one live spider would take so many unlikely steps that, for practical purposes, it can be ruled out. No such case is on formal record anywhere in scientific or medical literature.

Spiders avoid the bed, and avoid you

Three or four spider species live in most North American homes, Scientific American notes. They spend their time tending webs or hunting in places people do not occupy. A bed offers a house spider no prey, so it has no reason to cross it.

A sleeping human is also a bad place to explore. Spiders read the world through vibration. A sleeper breathes, the heart beats, and many people snore. Each of those sends vibrations that work as warning signals. Crawford and other experts describe a human to a spider as something like a huge breathing rock, part of the scenery, and a dangerous part at that.

Your body blocks the rest

Most people sleep with their mouths closed. If a mouth is open, snoring often comes with it, and snoring adds more vibration and moving air at the exact spot the myth needs a spider to enter.

Then there is touch. A spider crossing a face would wake all but the deepest sleepers, long before any swallowing reflex came into play. And swallowing in sleep is not an automatic trap. Crawford notes he knows of no evidence that people can swallow a solid object while asleep at all.

Stack the steps together. A spider must leave its hunting ground, cross a bed with no food on it, approach a vibrating face, enter an open mouth, and be swallowed by a person who does not wake. Each step is unlikely. The claim needs all of them, eight times a year, for everyone.

A number with no source

Versions of the claim shift, which is a tell. Sometimes it is eight a year, sometimes four, sometimes a pound of spiders in a lifetime. The Burke Museum notes that at four a year, a lifetime total of 20 spiders would mean a five-year life, and a pound of spiders would take about 5,000 years at that rate. Real measurements do not wobble like that. Folklore does.

So sleep easy. The spiders in the corner want insects, quiet, and distance from the giant vibrating animal in the bed. That is you, and they plan to keep it that way.