London: Got a tune trapped in your head? If you think it's only as the tune is catchy, think again. A new study says that stress, memories and triggers in environment all play a part.

Researchers at Goldsmith's College, London, say that songs which get stuck in people's heads -- a phenomenon called earworm -- can be triggered by just a single written word or a stressful experience, the 'Daily Mail' reported.

Dr Vicky Williamson, the lead researcher, has collected more than 2,500 "earworm experiences" while working with BBC 6 Music through her website

That included one woman who hears the same song – Nathan Jones, by Bananarama -- at stressful events like her wedding and childbirth, after first hearing it when she had an exam aged 16.

But it is not just stress which can cause a song to get stuck. Williamson's earworm experience was triggered by seeing a shoebox from the shop Faith in her office, causing her to have George Michael's song of the same name in head for hours.

She said: "Because music can be encoded in so many ways, it's what we call a 'multi-sensory stimulus'. Music is often encoded in a very personal and emotional way, and we know that when we encode anything with emotional or personal connotations, it's recalled better in memory."

The researchers believe earworms may be part of involuntary memory – the same part of the mind which makes people suddenly think of a friend they have not seen for ages.

Although popular film and TV shows make it more likely people have had exposure to one song -- with the TV show Glee's version of Journey's Don't Stop Believing featuring strongly in her research -- her studies show there is no particular song which is more likely to be an earworm.

She said: "When I had 1,000 earworm songs in my database, there were only about half a dozen or so that had been named more than once -- that's how heterogeneous the response was. It's a very individual phenomenon."

And if you are worried you will have that song stuck in your head forever? Dr Williamson recommends trying to displace it with a different tune.