You almost certainly eat zero bugs in your sleep. The widely repeated claim that people swallow eight spiders a year while sleeping has no scientific basis, and the real number is probably closer to none. Your body has multiple defense mechanisms that make swallowing an insect during sleep extremely unlikely, and bugs themselves have little reason to crawl into your mouth.
Where the “Eight Spiders a Year” Myth Came From
The most commonly cited origin story goes like this: in 1993, a magazine columnist named Lisa Holst wrote a piece for PC Professional about fake facts that spread through email chains. To prove how easily people believed nonsense, she allegedly included the claim that humans swallow eight spiders per year in their sleep, pulling it from a 1954 book called “Insect Fact and Folklore.”
The problem is that nearly every detail of this story falls apart under scrutiny. The 1954 book contains no such claim and doesn’t even have a section on spiders. When someone asked the Library of Congress to verify that PC Professional existed as a publication, it couldn’t. And no one has ever located Lisa Birgit Holst, whose full name happens to be an anagram of “this is a big troll.” So the myth about eating spiders has an origin story that is itself a myth, which tells you something about how eagerly people repeat surprising “facts” without checking them.
Why Your Body Won’t Let It Happen
Even if a bug wandered near your face at night, your sleeping body is surprisingly well-defended. Swallowing during sleep is rare and tightly controlled. Research published in the Proceedings of the National Academy of Sciences found that 98% of all swallowing events during sleep happen only when the brain briefly wakes up. These micro-arousals trigger a coordinated response: the brain activates, the glottis (the opening to your airway) snaps shut, your heart rate spikes, and only then does a swallow occur. This entire sequence is a protective reflex designed to prevent you from aspirating even your own saliva, let alone a foreign object.
Most swallows happen within the first two or three breaths after the brain rouses itself. In other words, your body doesn’t passively gulp things down while you’re unconscious. It wakes up just enough to swallow safely, then goes back to sleep. A random insect landing in your open mouth would be far more likely to trigger coughing, gagging, or full waking than a calm, oblivious swallow.
Bugs Don’t Want to Be Near You Either
From the insect’s perspective, a sleeping human is terrifying. Rod Crawford, an arachnid curator at the Burke Museum, has pointed out that sleeping people generate vibrations from breathing, heartbeat, and occasional movement that signal danger to spiders. A spider’s entire survival strategy depends on avoiding large vibrating things.
Biochemist Maggie Hardy at the University of Queensland put it simply: “You’d have to be unlucky for that to happen.” Not everyone sleeps with their mouth open, a warm exhaling mouth is not an inviting environment for most arthropods, and the combination of vibration, heat, moisture, and carbon dioxide makes a sleeping person’s face one of the last places a bug would choose to explore.
The Rare Exceptions
There are documented cases of insects ending up in human mouths during sleep, but they involve specific conditions rather than random bad luck. Oral myiasis, a condition where fly larvae develop inside the mouth, is linked to people who cannot close their mouths due to medical conditions, combined with poor oral hygiene and environments with high fly populations. These cases are uncommon and typically involve bedridden patients in tropical settings, not the average person sleeping in a bedroom.
Bed bugs are a separate concern entirely. They bite exposed skin while you sleep but don’t enter your mouth. Their behavior is to feed on blood from your arms, neck, and face, then retreat to hiding spots in mattress seams and furniture cracks.
What If You Did Swallow a Bug?
On the off chance you ever do swallow an insect (awake or asleep), your stomach acid handles it the same way it handles any other protein. Your body digests arthropods, including spiders, gnats, flies, and most common household insects, like any other food. For most people, swallowing a single bug causes no symptoms at all.
There are a few exceptions worth knowing about. Insects that sting, like bees or wasps, can cause localized swelling or pain if they sting on the way down. For people with insect allergies, this could trigger a serious allergic reaction including throat swelling and difficulty breathing. Some insects carry bacteria passively on their bodies. Flies, for example, can carry bacteria that cause severe diarrhea, though this typically resolves within a week. Swallowing fleas or beetles can occasionally transmit tapeworm species, though this is far more relevant to pets than to humans sleeping in a normal household.
Keeping Bugs Out of Your Bedroom
If the thought of nighttime insects still bothers you, a few practical steps make a real difference. Reducing clutter eliminates hiding spots for insects of all kinds. Washing bedding regularly in hot water and running it through a hot dryer kills any small arthropods that have taken up residence. Vacuuming thoroughly around bed frames, baseboards, and cracks removes both insects and eggs. Keeping windows screened and sealing gaps around doors prevents flying insects from entering at night.
These steps matter more for comfort and hygiene than for preventing the near-impossible scenario of swallowing a spider. The real benefit is fewer mosquito bites, no bed bug infestations, and a cleaner sleep environment overall. The spiders-in-your-mouth scenario, though, is one thing you can safely stop worrying about.