Even the Wind Is afraid (1968)

Claudia is a young girl who's suffering from terrifying nightmares at her all-girls boarding school. They involve the voice of a mysterious girl calling her name at all hours of the night. When Claudia and her friends break the rules by trespassing into a forbidden tower, harsh Headmistres Miss Bernarda punishes them by confining them to the school during Spring Break. Miss Lucia, a kind teacher, feels that the punishment has been too severe, since a similar incident happened five years before when a student received the same punishment with horrendous, tragic consequences, and she is afraid it might happen again.