London, Jan 24 (ANI): Couple's pillow talk after sex could be a key to happy relationship, psychologists say.
Psychologists at the University of Michigan have found that women whose partners finish off a night of passion by immediately turning over and nodding off are left feeling insecure and craving affection.
They said cuddling and talking after sex is a crucial way for a couple to express their commitment to each other.
In relationship terms, they say it could be just as important as what happens before sex, or even the act itself, the Daily Mail reported.
For the result, they questioned 456 heterosexual people, who completed online surveys about their sleep patterns with their partner.
Lead author Dr Daniel Kruger said they found the participants' desire for emotional bonding, affection and communication was greatest when their partner fell asleep first.
This was found in both men and women but previous studies have shown men invariably fall asleep first.
"When their partner feel asleep first, they craved that bonding time, for expressions of affection and endearment, and felt it was lacking," said Dr Kruger.
"A woman could be pregnant. Although with contraception that may not be the case anymore, we still have this psychology, and the post-coital time is when the couple makes promises to each other and establish commitment.
"The time couples spend together after sex might be as important as what happens before it in terms of building the relationship yet it has rarely been studied," he explained.
While this study did not confirm that men were more likely to fall asleep first, he said two of his previous studies and other research suggested it was true.
A study last year linked this to production of the hormones oxytocin and prolactin which create a sedative, or 'roll over and snore' effect in men after making love.
But Dr Kruger and his co-author Susan Hughes of Albright College in Pennsylvania believe there are evolutionary as well as chemical reasons for it.
They suggest falling asleep before their partner may be a non-conscious way for men to 'foreclose' any conversations about commitment.
This is just what their wives and girlfriends crave, they say, as women have more highly developed language skills.
Dr Kruger added: 'For men, in evolutionary terms there's more of an incentive to have other sexual partners to advance their reproductive success whereas for women there is more incentive to secure the relationship.'
While men with 'attachment avoidance' were less inclined to pillow talk after sex, women with 'attachment anxiety' were most upset about it, they found.
Women rated sleeping alongside the partner as more important than men, which the researchers suggested could be 'an anti-philandering strategy' to decrease their chance of being left for someone else.
In contrast men reported that women were more likely to nod off first if they went to bed without having sex.
This could be out of a primitive desire to 'guard their mate', or they could just be hoping they would change their mind, the study noted.
The study was published in the Journal of Social, Evolutionary and Cultural Psychology. (ANI)