Death of the sex drive - can testosterone help get it back?

In 1990, people aged 16 to 44 reported having sex an average of five times a month. By 2000, that had dropped to four times, and by 2010, to three. The next set of results are due later this year, and researchers expect the downward trend to continue. Senior health reporter for the BBC, Ruth Clegg, considers the great debate over whether testosterone can help restore sex drive. (Image: Getty)