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 our 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.
“This is the first research to quantify the length of the sexual afterglow and to examine its benefits,” said psychological scientist Dr Andrea Meltzer, of Florida State University, the lead author on the research.
“Our research shows that sexual satisfaction remains elevated 48 hours after sex. The afterglow appears to last approximately the same length of time that it takes for peak sperm concentration to be restored
“And people with a stronger sexual afterglow — that is, people who report a higher level of sexual satisfaction 48 hours after sex — report higher levels of relationship satisfaction several months later.”
Previous research has suggested that sex plays a crucial role in pair bonding, yet it was unclear why most adults report having sex with their partners every few days, not every day.
On average, participants reported having sex on 4 of the 14 days of the study, though answers varied considerably across participants.
And those who reported a stronger ‘afterglow’ were also more likely to be happier in their marriages.
The researchers stress that because the couples in this study were all young, in their mid 20s, and almost entirely heterosexual, future research is needed to explore sexual afterglow among older couples as well as gay and lesbian couples.
However, the researchers speculate that older couples in longer term relationships may have a longer sexual afterglow, which supports their long-lasting relationships.
Dr Meltzer and colleagues hypothesized that sex might provide a short-term boost to sexual satisfaction, sustaining the pair bond in between sexual experiences while also enhancing partners’ relationship satisfaction over the long term.
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.
Dr Meltzer added: “Together, the findings suggest that sex is linked with relationship quality over time through the lingering effects of sexual satisfaction.”
The research was published in the journal Psychological Science.