Half Angel

Half Angel is a 1951 Technicolor comedy directed by Richard Sale, starring Loretta Young, Joseph Cotten and Cecil Kellaway. Nora Gilpin Young, a prim and proper nurse, is engaged to the stuffy Tim John Ridgely. Unknown to both, Nora is a sleepwalker during her nocturnal forays, the lessinhibited side of her personality takes over.

That night, a sleepwalking Nora slips into a provocative dress and goes to the home of a startled John, behaving seductively. She doesnt reveal her name and he cant figure out where they have met. They spend several hours together, but she then gets away before John notices.John spots her on the street one day and excitedly brings up their evening together, but Nora has no idea what he is talking about and is greatly embarrassed, because this happens in front of Tim. She tells John he has misidentified her, and they rush away, leaving John confused. ........

Source: Wikipedia