Experts have a scientific explanation as to why women give their husbands excuses for not wanting to have sex.
They have found that the brains of females with a low libido behave completely differently to those with healthy sex drives, reports the Daily Mail.
According to a new research by the Wayne State University in Detroit, US, those with a low libido do not have the same rush of blood to certain brain cells during the passionate moments, which explained why they don't enjoy it.
Michael Diamond and his team asked women to watch erotic films and then a blank screen, and measured their brain's response using MRI scans.
They discovered that during the sex scenes, women with a normal sex drive had an increased flow of blood to parts of their brain. But those with low libido did not have any increase in blood flow.
Diamond said the findings offered 'significant evidence' that low sex drive is a genuine physiological disorder.
"Being able to identify physiological changes, to me provides significant evidence that it's a true disorder as opposed to a societal construct," he said.
The study, which was presented at the annual conference of the American Society for Reproductive Medicine in Denver, Colorado, involved 19 women diagnosed with hypoactive sexual desire disorder and seven women with normal sexual drive.