It's happened to all of us.
You're driving and right before you get out of the car, you hear a song. Hours later, you are humming, singing the lyrics. The song just won't leave your head.
So what causes these 'earworms'?
In the amazing video above, Dr. Sanjay Gupta explains how an emotional response in the brain can keep a song with you long after you've turned off your music player.
Video: How 'earworms' affect the brain