According to a Welsh psychiatrist "Using your iPod a lot could make you hallucinate".

The basis of Dr Victor Aziz of Whitchurch hospital in Cardiff's claim is that when people listen to music a lot it can cause musical hallucination. This is when a song "plays" constantly in the head.

Aziz claims that these musical hallucinations are causing sleeping problems in some of his patients. "People find they can't sleep and can’t think properly," he told London's Evening Standard newspaper.

Apparently this phenomenon is different to having a song stuck in your head because the sound is continuous and appears real.

Aziz said: "Having a song in your head every now and then is quite normal but musical hallucinations can be quite distressing."

The iPod is taking some of the blame for an increase in people suffering from this phenomenon because of its popularity, and no doubt because it is a headline grabber. Aziz suggests that the condition will become more common as people are inundated with music.