Help with name of song during Dr. Yang sequence (small spoilers)

When Alice first visits Dr. Yang [roughly 15 minutes into the movie] and he hypnotizes her, she reverts back to her first date with Douglas at a carnival and there is a very famous song that plays. Anyone know?

It's been driving me crazy for almost a year now since it is not on the soundtrack list and I heard it again on a cruiseship I went to and also at a beach. I know almost everyone must have heard it before...