In the fifth episode of the third season of Mad Men, "The Fog," Betty Draper gives birth to the Draper's third child. She is also dealing with the death of her father, which occurred in the previous episode. While in the hospital, Betty has a drug-induced delivery room hallucination, in which, among other things, she converses with her deceased parent.
While Betty is in this hallucinatory state, the song "Me Voy a Morir de Amor" (roughly, "I'm going to die of love") by Alberto Iglesias is played. It's extremely beautiful and perfect for her "dream states":