If you sleep with wet hairs, do you get cold ?
The evidences and studies so far do not suggest that you can catch Cold, if you sleep with wet hairs. Cold or common cold, is a respiratory tract infection caused by viral infections. There are 200 different viruses which can cause cold, rhinoviruses being the commonest. Usually these viruses spread from one person to another, either by hand-to-mouth contact or by inhalation.
Cold as we generally talk about as 'Common Cold', is an infectious disease. The virus shed by the infected person are either transmitted by the air they breath out or from their contaminated hands, they spread to the surface they touch such as door knobs, computer mouse, cell phones, etc. When another person touches that surface, virus contaminate their hands and when they bring their hands near their mouth or nose, they get infected.
Wet hairs or drinking very cold water or drinks can precipitate respiratory infection in those predisposed to but in themselves do not spread Cold.