Women are far more choosy about casual sex than men, who don't specially care whether a woman is moderately or exceptionally attractive as long as she hops into bed.

But German men are pickier than Americans and Italians - in that order - about who they spend a night in bed with, according to psychological research from Britain's Brunel University published in the journal Human Nature.

The study asked more than 400 male and 400 female students in the US, Germany and Italy to judge the role played by physical attractiveness in their willingness to go out with someone, go to their flat, or go to bed with them.

Women were more likely to go to a man's flat or agree to go to bed if he was exceptionally attractive.

"While men are not entirely insensitive to their request's attractiveness, women have higher standards," the authors concluded.