How dangerous are spider bites while sleeping?

Being crushed against a bedsheet by a human body just doesn't work well as a biting scenario (despite what everyone thinks) because spider fangs are underneath the spider. When pressed on from above, the spider may reflexively bite what it is standing on: the sheet, not your body. read more

Bad Widow bites tend to result in severe pain and muscle cramping, while bad Recluse bites tend to leave an unpleasant, slow-healing 'sore'. In almost all cases, though, the bite is unpleasant rather than dangerous. read more

If a spider does get on a bed, usually no bite will result. Spiders have no reason to bite humans; they are not bloodsuckers, and are not aware of our existence in any case. If you roll over onto a spider, most likely the spider will have no chance to bite. read more

But still, records show bites from these spiders are very infrequent. The bite of widow spiders like the black widow is one of the only well-recognized spider bites in North America, with obvious, unmistakable symptoms, said Rick Vetter, a retired arachnologist at the University of California at Riverside. read more