That loving feeling: how sex helps couples stay together
Having sex with your partner brings a 48-hour 'afterglow' which keeps people feeling content in their relationship, a new study suggests.
Although it is known that sex plays a central role in bonding, releasing the 'cuddle hormone' oxytocin, it was unknown how long the warm, fuzzy, post-coital effect lasted for.
To find out, US scientists invited 214 newlywed couples to fill out sex diaries for 14 days, which recorded how many times they made love, and how they felt about their relationships. They were then asked to re-evaluate their relationships six months later.
The researchers found that feelings of intimacy and relationships contentment, dubbed the 'afterglow' lasted for two days, but seemed to fade after three.
And the scientists believe they know why. Previous research has found that men's sperm concentration diminishes when having sex too much, but is restored by around day three.
So the afterglow could be an evolutionary adaptation to keep partners together while a man's sperm count recovers, increasing the chance of having a baby. Two days is also the maximum time that sperm can survive inside the female reproductive tract, so by abstaining for two days, the higher quality sperm has a greater chance of success.
Couples who reported a stronger 'afterglow' were also more likely to be happier in their marriages.
In the future, the team is hoping to study whether a stronger afterglow predicts whether a partner will be faithful. A shorter afterglow may signal a weaker relationship.
The research was published in the journal 'Psychological Science'.