Almost all of us have experienced getting a song stuck in our head at one time or another in our lives. Often it happens first thing in the morning and we find ourselves waking up to a tune we heard the night before, but on other occasions it can happen without warning and creep into your brain with no warning or explanation.
While this might sound fairly pleasant, in some cases it can actually be quite irritating as the same few lines go round and round in your head and people start shouting at you for incessant humming.
But what's actually going on here? And how can you change it? Let's take a look at the biology behind it.
What Is an Earworm?
Technically a song that gets stuck in your head is called an 'earworm' which comes from the German 'Ohrwurm' and is described by some as a form of 'auditory hallucination'. Now while for most of us this might be an irritation that lasts an hour or so, in some rare cases earworms can actually be chronic – lasting for years, particularly in the elderly, and sounding much more as though the band is actually in the room with you.
What Causes Them?
If you were hoping to get a clear answer here to what an earworm is, then I'm afraid you're going to be disappointed. Earworms aren't fully understood by scientists yet, and there is a fair bit of disagreement over what causes them.
One theory is that earworms are caused by your brain trying to cement a memory – firing the same neurons that the sounds fired in the same way that REM sleep is believed to be cementing memories formed during the day.
However for many this theory isn't particularly convincing, and particularly when it doesn't seem to happen with other sounds. What's particularly interesting about earworms is that some songs are much more common than others and are generally up-beat, melodic tunes. According to a professor of Marketing at the University of Cincinnati, certain pieces of music have 'properties' that make them more likely to get 'stuck' and his belief is that your brain recognizes something extraordinary or unusual about it and so begins cycling it to try and draw attention to it (a process that could be to do with our evolutionary history). And what properties does Dr Kellaris outline? Repetitiveness, simplicity and incongruity – which is some kind of unexpected deviation from the rhythm; and he points to America from West Side Story as an example.
In an interesting study in 2003, Kellaris also showed that the most common earworms were ones that had lyrics – with instrumental cases being relatively rare. This could fit with his theory if you were to think of spoken words as being likely to be more relevant to us – meaning our brain might be more inclined to draw attention to them. In another study he also found that anxiety was a predictive factor in the phenomenon with worry-wart types being significantly more likely to experience it.
So the best we can say currently is that it's an auditory hallucination that could be caused by your brain thinking that the tune is somehow noteworthy.