The Very Real Science Behind "Sexual Afterglow"

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You don’t need science to tell you how awesome and close to your partner you feel after sex — but it’s pretty cool when it does. A new study from Florida State University confirms that “sexual afterglow” is very real and lasts a good 48 hours after sex, helping to bond couples and boost relationship satisfaction long-term.

Experts have long known that sex keeps married couples connected, but since most duos don’t get busy every single day, the researchers wondered how long the afterglow lingers and whether it’s key to keeping the fire burning between romps. To find out, they asked 418 newlyweds to keep a diary for two weeks straight. Each day, the couples noted independently whether they had sex that day and rated how they felt about their sex life, their spouse, and their relationship overall.

“We found that when couples reported having sex on any given day, their sexual satisfaction was elevated that day but also for the following 48 hours, regardless of whether they had sex on those days,” says lead researcher Andrea Meltzer, a psychology professor at Florida State. “We know from past studies that there are biological changes after sex, such as increases in dopamine, oxytocin, and vasopressin, but we didn’t know much about what happens cognitively.”

Meltzer suspects the cognitive benefits of the sexual afterglow demonstrated in this study evolved over time. “From an evolutionary standpoint, it wouldn’t be viable to just have sex all the time,” she says. “You need time to find food, eat, and do other things to enhance survival. Therefore, these findings suggest that sex may have evolved to have a cognitive function that lets us take breaks between sexual encounters and still feel satisfied and bonded.”

To gauge the afterglow’s long-term effects, the researchers assessed the quality of each marriage four and six months after the trial period. The couples rated highest for sexual and relationship satisfaction — those with the strongest afterglows — during the 14-day diary period also reported happier, healthier relationships later on.

“This supports the idea that sex functions to pair-bond couples, which means keeping them happy, committed, and tied together over time,” Meltzer says. “Marital satisfaction produces many positives like less conflict and less infidelity in relationships.”

Although this study focused on newlyweds, Meltzer speculates that spouses who’ve been married for years, as well as unwed partners in committed relationships, glean similar benefits, although the length and intensity of the afterglow may differ slightly. “Sexual satisfaction may last longer in couples who’ve been married for longer because sex isn’t as necessary from a reproductive standpoint,” she says. “It’s also possible that the afterglow is shorter and maybe they need to have sex more often to get the same effects.”

What is known for sure, Meltzer says, is that happier couples have healthier, more solid relationships. And since sex is a crucial contributor to marital satisfaction, it pays to make it a priority.