Love really does have a strange effect on people, say scientists.
Love affects hormones and brain chemicals
Italian researchers carried out tests on 12 men and 12 women who had fallen in love during the previous six months.
They found that men had lower levels of testosterone than normal, while the women had higher levels of the hormone than usual.
"Men, in some way, had become more like women, and women had become like men," Donatella Marazziti of the University of Pisa told New Scientist magazine.
"It's as if nature wants to eliminate what can be different in men and women, because it's more important to survive at this stage," she said.
'Love is blind'
The findings come as another study suggests that love may indeed be blind.
Researchers at University College London have discovered that being in love can affect key circuitry in the brain.
They found that the neural circuits that are normally associated with critical social assessment of other people are suppressed when people are in love.
They said the findings may explain why some people are often "blind" to their partner's faults.
Both studies add to the growing evidence that love can have a strange effect on the body.
Previous research by the Italian researchers, published in 1999, suggested falling in love played havoc with key chemicals in the brain.
They found that people who were in love had lower levels of serotonin.
In fact, their serotonin levels were found to be the same as people with obsessive compulsive disorder.
Speaking at the time, the researchers said the finding may explain why people who are in love can sometimes obsess about their partner.
Professor Gareth Leng of the University of Edinburgh is also carrying out research in this area.
"It's about understanding ourselves a little bit better," he told BBC News Online.
But Professor Leng said the research could one day lead to new treatments for people who are having relationship problems.
"We know that a very large proportion of adults do report dissatisfaction with bonding or sexual experience.
"I wouldn't rule out the possibility of some sort of therapeutics in the future," he said.