Is sleeping with wet hair really bad for your eyesight or will it result in headaches? My mom has been telling me this for years but I'm not sure if it's based on scientific fact.

There is no scientific evidence, actually. I have been sleeping with wet hair ever since I can remember and it has no effect on me at all. It may depend on how comfortable you are when you sleep, but the reason why I sleep with wet hair because I sleep more soundly and I feel more refreshed.