Studies show that during sex, men watch women's faces to gauge how much they are enjoying - or faking - the proceedings.

According to sex expert, Tracy Cox, who has analysed how real couples have sex during The Sex Inspectors, our expressions during orgasm vary widely and differ greatly from what might be shown on film.

Referring to this expression as the "orgasm face", Cox assures readers of the Daily Mail that it's nowhere near as pretty as you might hope. In fact, she observes that most people's orgasm face is a scrunched up and sweaty.

But as Cox points out, sex is not meant to be a dignified act of composure, but rather one of a more animalistic nature that has us caught up a moment led by sensation and lust.

All the better if you keep your eyes open and fixed on your partner during climax. Cox cites couple's counsellor David M Schnarch's belief that to keep your eyes on your partner when you're orgasming helps boost intimacy.

Cox has encouraged couples she has counselled to try keeping their eyes trained on one another during orgasm. While many say that the first few times made them feel self-conscious, this soon gives way to being sharing some of the most erotic and loving moments they'd experienced.

It might not be for everyone, admits Cox, but it's worth trying out.