Sexy bedroom eyes should be reserved for the bedroom only, a new study has found.

Both men and women have judged that low-lidded look as untrustworthy in a recent study, with women saying they wouldn't consider a man with such a look as good boyfriend material.

"A lot is conveyed in a glance," study researcher Daniel Kruger, a psychology professor at the University of Michigan, told LiveScience.

The researchers took two photos of two white males in their early twenties – one with eyes half-closed and the other open-eyed – and showed it to two groups of undergraduates who were asked to give their opinion on whether they would trust these people easily.

Pictures of the two men with eyes half-closed were marked as untrustworthy, while those pictures of the men with open eyes and a normal gaze were seen as sincere. In fact, male participants answering the questions typically said they'd consider the open-eyed men good business partners or neighbours, while women thought they were long-term boyfriend material. In fact, 71 percent of women said they would much rather marry or sustain a relationship with the man with the normal gaze.

The study also found that both sexes deemed the pictures in which the men wore their sexy, low-lid look as only wanting a fling.

This sexy gaze didn't win the men any points in the attractiveness stakes either. Open-faced portraits were rated as far more handsome.

"You don't gain so much of an advantage by doing this expression unless you're already engaged with someone who is interested in you, or who you have a chance with, so don't overuse it," added Kruger.