Waking up in a stranger's bed can fill us with regret.

So it's not surprise that scientists found 35 per cent of women tend to feel guilty after having a one night stand.

But just a fifth of men regret getting into bed and doing the deed with a stranger, a study has revealed.

In fact, 60 per cent of them are annoyed by their decision to turn down their most recent opportunity of casual sex.

And the reason why women tend to feel guiltier could be down to evolution, new research suggests.

Women tend to feel more guilty about experiencing a one night stand. While just a fifth of men regret getting into bed and doing the deed with a stranger, scientists have found

To assess the attitudes towards one night stands, researchers questioned Norwegians - supposedly of a more sexually liberal background.

Some 263 students aged between 19 and 37 who had experienced one casual sexual encounter were surveyed.

It was far more common for women to regret saying yes (35 per cent), the researchers from Norwegian University of Science and Technology discovered.

Only 30 per cent reported feeling happy with their most recent one night stand. But more than half of men said the same.

It could be because men had orgasms during sex to a far greater extent than the women, they found in the journal Evolutionary Psychology.

While both genders were more regretful about one night stands that did not end in them climaxing.

At the same time, nearly 80 per cent of women were happy they refused their previous chance of having casual sex.

But just 40 per cent of men feel that they made the right decision in passing up the opportunity.

But the reason women are more guilty could be down to evolution, as they seek higher quality partners, new research suggests

Study author Professor Leif Edward Ottesen Kennair said: 'Women regret that they agreed to a one-night stand more often than men. Men regret passing up the chance more than women.

'Men enjoy casual sex considerably more, but this doesn’t explain the gender difference in regret, because gender is the most important influencing factor for both orgasm probability and sexual regret after casual sex.'

DOES SIZE MATTER FOR CASUAL SEX? Women prefer a larger penis for a one-night-stand than for a long-term relationship, a study in December found. But even the 'smaller' option is bigger than the national averages in the US and Britain, scientists discovered. Contrary to received wisdom, the study also showed overwhelmingly that - although women prefer slightly bigger than average penises - they are more concerned with girth. Advertisement

They are less happy about the experience - mainly due to their worries of pregnancy, STIs and getting a bad reputation.

While it is conceivable that women feel more regret due to them not achieving as much sexual pleasure, evolution could also be to blame, with men and women both having varying attitudes towards sex.

The researchers pointed to the fact that, theoretically, men can father thousands of children.

This was used frequently in the past to boost the chances of having children that would survive.

But this meant that the quality of their sexual partner is compromised.

The researchers believe this has caused many males to care only about the number of sexual opportunities possible to them.

However, women are more focused on quality partners.