Please turn on JavaScript. Media requires JavaScript to play.

The world's first 'tickle spa' has opened in Madrid, promising to tickle clients into a state of relaxed bliss.

But why do we laugh when we are being tickled and how can it be a relaxing experience?

Dr Chris Smith from the pathology department at Cambridge University tells Radio 5 live Breakfast why the anticipation of being tickled is a basic survival instinct.

For more radio 5 live interviews and stories, please visit the Best Bits page.