Sleep My Love
(1948)

Alison (Claudette Colbert) wakes up on a train, with a gun in her purse, and no recollection of how she got there.  She is escorted home by Bruce, who falls for her, even though she is married.  She keeps seeing a menacing man with thick glasses.  She also sleepwalks, and does not remember things she has done.

Her husband, Richard Courtland (Don Ameche) is responsible.  Alison is wealthy, and Richard lives off her money.  Richard is having an affair with Daphne. He is drugging and hypnotizing Alison.  His plan is to drive her to commit suicide or convince the police she is insane, so if he kills her they think it is suicide.  The man with the thick glasses is working for Richard.

Bruce suspects something is up, and begins investigating on is own.  He finds evidence of Richard's affair and that Richard is lying about things.  The man with glasses shows up at the house to frighten Alison.  Richard incites Alison to shoot the man.  Richard figures if Alison is convicted of murder, he still gets the money and is free of her.  However, she injures, but does not kill the man.  The injured man reveals the whole plot, then shoots Richard.  Bruce arrives.  The man with glasses flees from Bruce and falls to his death.  Alison and Bruce are left to start a new life together.

Thanks Joseph C!

IMDB