Maybe it’s the latest hit song or something you heard years ago that was playing on repeat in your head today. These snatches of songs drive us mad almost daily, but what causes them?

The lines or bits of songs that play in a loop are often called “earworms,” which was translated from the German word, Ohrwurm. The French phrase for an earworm is musique entêtante, and in Italian it is a canzone tormentone. The former means “stubborn music” and the latter “tormenting songs.”

Dr. Vicky Williamson, a memory expert at Goldsmith’s College in London, set up a website where people recorded their earworms. Her goal was to try to see if some songs were “catchier” than others.

Williamson found that unless a film or TV show had featured that song recently, or it was very popular, the earworms varied greatly with little overlap. The songs that get to be your earworms depend on who you are, unsurprisingly.

There are many theories about why people get earworms in the first place. Williamson says that earworms may be a part of “involuntary memory,” which also prompts you to eat a certain food after it pops into your head, or to think about someone you haven’t seen in years.

Another theory is that music gets stuck in our heads because of how humans evolved, with no written language to rely on.

“For a very long period of time, we needed to remember information,” said Daniel Levitin, an expert in the neuroscience of music.

Levitin said that a combination of rhyme, rhythm and the melody of music helps us recall music easier than words alone. Now that evolutionary advantage has turned into an annoyance.

Dr. Williamson said that earworms are most commonly caused by recent or repeated music exposure, word, situation, or person triggers, stress, and your mind wandering.

Levitin said that the main question he gets about earworms is how to turn them off.

“Just think of another song and hope that’ll push out the first one,” Levitin said.