Do people really swallow spiders in their sleep?

No, not in the way the popular statistic claims. The idea that the average person swallows four, eight or twenty spiders in a lifetime or a year has no basis in fact. Specialists allow that a sleeping person could conceivably swallow a spider, but they describe it as a strictly random event, and they know of no recorded case. [1] [2]

The legend circulates in several versions. Rod Crawford, the arachnid curator at the Burke Museum in Seattle, notes that the numbers do not hold together even on their own terms: four a year would imply a five-year lifetime if the lifetime figure were twenty. [1]

Spiders have little reason to approach a sleeper. Most North American homes hold three or four spider species, which stay near their webs or hunt in areas away from people. A bed offers no prey. Bill Shear, a biology professor and former president of the American Arachnological Society, says spiders regard humans much as they would a big rock. [2]

Spiders also sense vibration strongly. A sleeper's breathing, heartbeat and possible snoring all produce vibrations that would warn a spider of danger. Crawford says a sleeping person is not something a spider would willingly approach. On the human side, a spider crawling over the face would likely wake many people. [2]

One American spider specialist has listed five things that would all have to happen: you sleep with your mouth open, a spider is on your bed, it crosses your body, it actually wants to enter your mouth, and you swallow it rather than react. [3]

No such case is on formal record in the scientific or medical literature, according to Crawford. He points out that millions of people have watched someone sleep, yet there is no eyewitness account of a spider entering a sleeper's mouth. People who say it happened to them rarely have evidence, and Crawford says they usually report having thrown it away. [1] [2]

Crawford describes one account he finds credible: a woman who, as a child in a grassy field on a windy day, had a ballooning spider blow into her open mouth. That was while awake. Maggie Hardy of the University of Queensland likewise says a ballooning spider drifting into a sleeper's mouth is conceivable, but would take considerable bad luck. [1] [3]

Hardy cites research by a group of scientists who found that strong disgust at spiders, together with a phobia of contact with them, leads to an unrealistic expectation that we eat them unconsciously. Crawford also hears, about once or twice a year, from people who say they once found a spider leg in their mouth, though none has produced evidence. He suggests such stories are similar enough to form a separate urban legend. [3] [2] [1]