In news that shouldn’t surprise anyone who’s ever had sex with another human being, scientists claim knocking boots makes people like each other more – but only for a little while.

A new study suggests we experience a 48-hour ‘afterglow’ after sex that temporarily keeps us feeling happy and satisfied in our relationships. This is the first time a study has shed light on the duration of the effects of the ‘cuddle hormone’ oxytocin, which is released during post-coital bonding.

U.S. scientists had 214 newlywed couples fill out sex journals for two weeks, tracking how many times they had sex and how they felt about their marriages. Six months later, they were asked to re-evaluate their relationships.

The researchers found that feelings of intimacy and contentment (or the ‘afterglow’) typically lasted for about two days after couples had sex, but faded after three.

Scientists believe this is because men’s sperm concentration diminishes after too much sex, but it’s restored around day three. That means the afterglow could be an evolutionary adaptation meant to keep partners together until the man’s sperm count recovers, thus improving a couple’s chances of conceiving a baby.

“This is the first research to quantify the length of the sexual afterglow and to examine its benefits,” said lead author Dr. Andrea Meltzer of Florida State University.

“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.”

On average, study participants reported making love four out of 14 days, and those who reported stronger afterglows were more likely to be happy in their relationships.

“Together, the findings suggest that sex is linked with relationship quality over time through the lingering effects of sexual satisfaction,” said Meltzer.

The findings were published in the journal Psychological Science.

h/t The Telegraph