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.

It's really true.. During sleep, body temperature rises & body heats, the wet hair causes headaches. wet hair can also cause infections like cold & hair breakage. If room temp is warm, then the effect is less. In cool temp room, scalp will loss a large amount of heat energy. Chances of getting headaches r more. I have very long & thick hair, so I experienced all these. Thick hair, more moisture & it will take more time to dry hair.