Sex is required for human reproduction and to help maintain the population, but new research suggests there may be another equally important need for sex: To bond couples. The study found that while sex may only occur for a few minutes every couple of days, the “afterglow” from sex can last up to 48 hours. This afterglow may play a crucial role in bonding couples, increasing relationship satisfaction, and ensuring that a relationship will last.

The study, now published online in Psychological Science, found that couples can experience a sexual "afterglow" that lasts for up to two days, and this afterglow, not the sex itself, is linked to higher relationship satisfaction among couples who are more sexually active. This finding helps to reinforce a study published in February that suggested it was the time spent cuddling after sex, not the pleasure of the orgasm, that made sexually active couples happier than those who made love less frequently.

Read: Having Sex Will Make You Like Your Job More, According To Science

"Our research shows that sexual satisfaction remains elevated 48 hours after sex," says lead study author Andrea Meltzer, in a recent statement. "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."

For the new study, the team examined past data on newlywed couples and their sex lives. The team looked at both frequency of sex and lingering relationship satisfaction, and found time and again that a single act of sex on any given day was linked to lingering sexual satisfaction for the next two days. What’s more, this association remained regardless of individuals' age, gender, personality traits, length of relationship and how often the couple had sex on average.

In addition, this “sex afterglow” also seemed to have important long-term results. The study showed that participants who reported high levels of sexual afterglow reported higher initial marital satisfaction, and had less steep declines in satisfaction in the first few months of their new marriage.

"This research is important because it joins other research suggesting that sex functions to keep couples pair bonded," added Meltzer.

While this study, along with others, highlights the social and mental health importance of an active sex life, other research suggests that Americans are having less sex than ever before. The research studied the frequency that Americans reported having sex from 1989 to 2014, and reported steady declines, finding that although all Americans are having less sex, this trend was particularly worrisome among the younger Millennial generation and among married couples. Traditionally, younger generations and married couples were more sexually active than other populations, but as shown by this recent study, this is no longer the case.

Source: Meltzer AL, Makhanova A, Hicks LL, et al. Quantifying the Sexual Afterglow

The Lingering Benefits of Sex and Their Implications for Pair-Bonded Relationships. Psychological Science. 2017

See Also:

Surprising Reason More Sex May Be Key To Happiness: Cuddling And Affection Increase Couples' Wellbeing

Who Is Having Less Sex? Americans (Including Millennials), Despite Science That More Sex Is Better