Lots of mythology is compiled from many incomplete sources, and not all common accepted stories will completely mesh up with others. It’s also not uncommon for the myth of one village to be completely different from another regarding a particular entity, even if the towns are within a hour walk. What we have now is often just what survived.
Best be careful when changing sheets anyway. It’d be a shame if your mattress wasn’t properly killed before being shipped from Sqornshellous Zeta and it went on a flollop rampage after being exposed to too much sunlight.