Let's be honest. Did any of us really believe that old chestnut that men think about sex every six seconds? After all, that would mean the average chap having up to 10,000 racy thoughts a day. Which would barely leave him time to dim the lights, put on some romantic music and snuggle up, let alone anything else.
Nevertheless, scientists have decided to put the six-second theory to the test.
Their extensive research has found that men do think about sex rather a lot.
But it's more in the region of every 50 minutes, or a less frenetic 19 times a day. Women, too, let their minds wander to matters risque. But they only manage an average of ten thoughts a day.
The researchers worked out how many times men and women thought about sex by giving them a 'clicker' machine to press when they had any such thoughts.
They were also told to click every time they thought about eating or sleeping.
And while women's minds did turn to sex ten times a day, they spent much more time thinking about food.
They had an average of 15 thoughts a day relating to hunger pangs, the desire to snack or even anticipating what they were having for lunch. While men also thought about food, sex remained the biggest preoccupation.