Are You Really Swallowing Spiders in Your Sleep?

The idea that humans swallow eight spiders per year while sleeping has circulated for decades, causing discomfort and anxiety for many people. This widely believed “fact” has wormed its way into our collective consciousness, appearing in countless emails, social media posts, and even some publications. But before you start sleeping with a mask or mosquito net, it’s worth examining whether there’s any truth to this creepy claim. In this article, we’ll explore the origins of this myth, analyze its scientific validity, and provide evidence-based information about whether you need to worry about unwelcome eight-legged visitors during your slumber.

The Origins of the Eight Spiders Myth

The claim that the average person swallows eight spiders yearly while sleeping is a classic example of how misinformation can spread rapidly and become accepted as fact. This statistic gained significant traction in the early days of the internet, appearing in chain emails and on early websites. However, tracing the exact origin has been challenging for fact-checkers and researchers.

One commonly cited source is a 1993 magazine article about the persistence of false beliefs, which ironically included this spider statistic as an example of absurd claims people readily believe. The irony thickened when readers missed the point and began sharing the spider “fact” as genuine information. Like many internet legends, it spread quickly without verification, demonstrating how easily misinformation can become widely accepted when it triggers emotional responses like disgust or fear.

What Science Actually Says About Sleep and Spiders

Scientific evidence overwhelmingly contradicts the notion that humans regularly consume spiders while sleeping. Entomologists and arachnologists—scientists who study insects and spiders, respectively—have repeatedly debunked this claim. According to experts, spiders have sophisticated sensory organs that help them detect vibrations, air currents, and potential threats. A sleeping human produces all three in abundance: we breathe, snore, shift positions, and emit heat, creating an environment that most spiders would consider hostile rather than inviting.

Additionally, spiders are primarily motivated by survival and feeding. They have evolved to hunt prey efficiently, and humans don’t resemble anything in their typical diet. From an evolutionary perspective, there would be no advantage for a spider to approach a large, moving, breathing mammal, especially when entering the mouth area would expose them to moisture and potential harm. Simply put, spiders have neither the motivation nor the desire to explore human mouths during sleep.

Human Sleep Patterns and Spider Behavior

Understanding both human sleep patterns and spider behavior provides further evidence against this myth. During sleep, humans aren’t completely unconscious or immobile. We regularly move, change positions, and maintain basic reflexes. Most people would wake up or reflexively react to the sensation of a spider crawling on their face or near their mouth. The body’s protective mechanisms don’t completely shut down during sleep, particularly for potentially threatening stimuli.

Spiders, meanwhile, are primarily nocturnal hunters that prefer to avoid large animals. Most house spiders establish webs in undisturbed areas and wait for prey to come to them rather than actively hunting. The species that do hunt actively typically follow prey trails and seek specific targets—not sleeping humans. Their survival instincts would generally direct them away from the vibrations, heat, and carbon dioxide that humans emit during sleep, making a deliberate journey into a human mouth extremely unlikely.

Statistical Impossibility of the Claim

When examined mathematically, the “eight spiders per year” claim quickly falls apart. If this statistic were true, it would mean that across a global population of approximately 8 billion people, humans would collectively swallow about 64 billion spiders annually. This would represent a significant portion of the spider population in human-inhabited areas, which is simply not plausible.

Furthermore, if we consider that many people live in urban environments with relatively low spider populations, or in regions with seasonal variations where spiders are less active during certain months, the numbers become even more improbable. The statistical unlikelihood, combined with the lack of documented medical cases of spider ingestion during sleep, provides strong evidence against this widespread belief.

Why We Find the Myth So Believable

Despite the scientific evidence against it, the spider swallowing myth persists in popular culture. This persistence can be attributed to several psychological factors. First, the claim evokes a strong emotional reaction—typically disgust or fear—which makes it memorable and more likely to be shared. Psychologists have found that information that triggers emotional responses tends to be more readily believed and disseminated.

Additionally, the claim plays into common fears about both spiders and vulnerability during sleep. Arachnophobia is one of the most common specific phobias, affecting an estimated 3.5-6.1% of the global population. When combined with the natural vulnerability we feel while sleeping, the spider myth creates a perfect storm of believability, despite its lack of factual basis. Our brains are wired to pay special attention to potential threats, sometimes overriding critical thinking in the process.

Real Spider Encounters During Sleep

While the eight-spider claim is false, it’s worth acknowledging that genuine spider encounters during sleep can occasionally occur. However, these are extremely rare events, not regular occurrences. In most documented cases, people become aware of the spider and wake up before any ingestion could take place. These incidents typically happen in environments with high spider populations or during unusual circumstances, such as camping outdoors.

Medical literature contains very few verified cases of spider ingestion during sleep. When such incidents do occur, they often result in immediate waking, coughing, or other reflexive responses that expel the spider. The human body has evolved protective mechanisms specifically to prevent the accidental ingestion of insects, spiders, and other potential hazards during sleep. These mechanisms include sensitivity to touch around the face and mouth, as well as reflexive responses to unusual stimuli.

How Spiders Actually Behave in Human Dwellings

Understanding how spiders typically behave in our homes helps clarify why the swallowing myth is so implausible. Most house spiders establish themselves in quiet, undisturbed locations like corners, basements, attics, or behind furniture. They create webs in these locations and generally remain there unless disturbed. The common house spider (Parasteatoda tepidariorum) and other similar species prefer stability and are unlikely to venture far from their established territories without good reason.

When spiders do move around homes, they typically follow walls and avoid open spaces where they might be vulnerable to predators. They’re most active at night when hunting for insects, but their prey consists of flies, mosquitoes, and other small arthropods—not sleeping humans. Spiders are generally beneficial housemates that help control pest populations, and they have evolved to coexist with humans by staying out of our way, not by crawling into our mouths.

The Psychology of Urban Legends

The spider-swallowing myth belongs to a broader category of urban legends and misinformation that persist despite contradictory evidence. These myths often share common characteristics: they’re simple to understand, emotionally evocative, seemingly plausible at first glance, and often contain a kernel of truth (in this case, that spiders do exist in our homes). Psychologists who study the spread of misinformation note that such beliefs often fulfill psychological needs, such as making sense of a chaotic world or confirming existing fears.

The internet has greatly accelerated the spread of such myths. In what some researchers call “the illusory truth effect,” repeated exposure to a statement increases the likelihood that people will judge it as true, regardless of its actual veracity. Each time we encounter the spider myth, it becomes more familiar and, paradoxically, more believable. This psychological tendency, combined with the limited fact-checking that occurs during casual information sharing, has allowed the eight-spider claim to persist despite being repeatedly debunked.

Other Common Myths About Spiders

The spider-swallowing myth is just one of many misconceptions about these eight-legged creatures. Another persistent myth is that daddy longlegs (Pholcidae) are the most venomous spiders in the world but can’t bite humans because their fangs are too short. In reality, daddy longlegs’ venom is relatively mild, and some species can indeed penetrate human skin, although their bites cause minimal reactions. Similarly, many people believe all spiders build webs, when in fact numerous species, like wolf spiders and jumping spiders, actively hunt without webs.

There’s also widespread confusion about spider aggression. Most spiders are shy, non-aggressive creatures that bite humans only as a last resort when threatened or accidentally pressed against the skin. Despite their fearsome reputation, spiders generally prefer to flee rather than confront creatures thousands of times their size. These misconceptions highlight our complicated relationship with spiders—creatures that are simultaneously beneficial to our ecosystems yet often feared and misunderstood.

How to Keep Spiders Out of Your Bedroom

If you’re concerned about spiders in your sleeping environment (even though they’re unlikely to end up in your mouth), there are several effective strategies to minimize their presence. Regular cleaning reduces the insects that spiders prey upon and removes webs, making your bedroom less appealing to arachnids. Sealing cracks around windows, doors, and foundations prevents spiders from entering in the first place. Removing clutter, especially items stored under beds or in closet floors, eliminates potential hiding spots.

Natural deterrents can also be effective. Spiders dislike strong scents like peppermint, tea tree, citrus, and vinegar. Diluted essential oils or vinegar solutions sprayed around entry points can discourage spiders from crossing these boundaries. Additionally, maintaining appropriate humidity levels with a dehumidifier can make your bedroom less attractive to moisture-loving spider species. These preventative measures are far more effective—and certainly more practical—than worrying about accidentally swallowing spiders during your sleep.

The Value of Critical Thinking About Animal Myths

The spider-swallowing myth serves as an excellent case study in the importance of critical thinking and scientific literacy. When we encounter claims about animal behavior, especially those that seem unusual or alarming, it’s valuable to consider the source, look for scientific evidence, and evaluate whether the claim makes biological sense. In the case of spiders entering mouths during sleep, a basic understanding of both human physiology and spider behavior quickly reveals the implausibility of the claim.

This critical approach has broader applications beyond dispelling myths about spiders. Similar misinformation exists about many animals, from the belief that bats are blind to claims that ostriches bury their heads in sand when threatened. By approaching such claims with healthy skepticism and seeking information from reliable sources, we can develop a more accurate understanding of the natural world and the creatures with which we share our environment.

The claim that humans swallow eight spiders yearly during sleep is a compelling example of how misinformation can persist despite contradicting scientific evidence. Based on our understanding of spider behavior, human sleep patterns, and the statistical improbability of such frequent occurrences, we can confidently conclude that this widely believed “fact” is indeed a myth. Spiders have neither the motivation nor the desire to enter human mouths, and our bodies have protective mechanisms that would prevent such accidental ingestion.

Instead of worrying about unwelcome arachnid visitors during your slumber, it’s more productive to appreciate the beneficial role that spiders play in our environments by controlling insect populations. If you’re still concerned, implementing simple preventative measures to reduce spider presence in your bedroom can provide peace of mind. Understanding the truth about spiders not only helps dispel unnecessary fears but also fosters a more accurate appreciation of these fascinating creatures that have evolved alongside humans for millions of years.

So tonight, when you lay your head on your pillow, rest assured that while you might share your home with spiders, they’re almost certainly not interested in exploring your mouth. Sleep well, and let both you and your eight-legged housemates enjoy your respective spaces in peace.