There is a widespread urban legend that says that people eat spiders while they are sleeping. This myth has no scientific basis and is just plain ridiculous.
It is true that sleeping humans give off vibrations, but they do not have enough room in their mouths to swallow a spider. The only way a spider could travel into a sleeping human’s mouth is if it was dropped in at the perfect moment.
Spiders are highly sensitive creatures, and they do not like to spend much time with humans. They also tend to shy away from snoring humans. If a sleeping person snores, the spider will run.
Another way spiders may fall in is due to breathing. They prefer to hang out in quiet, uninhabited areas of the house. During sleep, they can sense air currents, and this is another reason they do not like to be around snoring humans.
While it is possible for a spider to fall from the ceiling or the side of a bed, it is unlikely that it would fall into the mouth of a sleeping person. It would have to hit the person dead center, or it would need to crawl out of the mouth.
If a spider did crawl into the mouth of a sleeping person, it would probably end up in the throat. Spiders do not have strong eyesight, and they do not want to tickle the tongue.
The idea that a sleeping person can swallow a spider has been around since 1954, but there is no evidence to support this. Some of the claims are simply made up, but they spread through email chains.