I have heard people say this many times, and at first I thought it was ridiculous, but after a while it seemed like their was a fair amount to truth to it so I decided to check it out. To be honest, I was hoping that I would find out that it was false because it is a scary though to think that spiders are crawling into my mouth while I sleep and I eat them.
According to an article written by Annie Snead she seems to believe that this theory is false. She has quotes from scientists that show that based on common sense alone, this idea must be false. From a spiders point of view they are much smarter than that. There is no reason for them to go into a humans bed, and if they did crawl into our bed they would not head into a humans mouth which would be giving off vibrations that scare them away. From a human perspective, most people would be awoken if they feel a spider on them, especially if it is going down their throat. Based on these thoughts it seems unlikely that humans eat spiders in their sleep.
Although these are just opinions and not facts, these still do make a lot of sense, and I think it provides strong evidence against this theory. Just based on this common sense, it doesn’t seem likely that a spider would be crawling into somebody’s mouth. This was definitely a relief to me because I know I do not want to go to sleep knowing that a spider may end up crawling down my throat.