Researchers suggest sex leads to an afterglow that plays a role in long-term marital satisfaction.
Lead author Andrea Meltzer, of Florida State University, and colleagues recently reported their findings in the journal Psychological Science.
A number of studies have shown that sex contributes to short-term bonding between partners, but the researchers note that the majority of couples do not engage in sexual activity every day.
According to the International Society of Sexual Medicine, only 21 percent of married men and 24 percent of married women have sex on 4 or more days each week.
So what bonds partners in between sexual activity?
Meltzer and colleagues speculated that sex produces an afterglow, or a period of sexual satisfaction, that enhances partner bonding in the periods between sexual activity, and that this boosts relationship satisfaction in the long term.
The researchers tested this theory by analyzing the data of two studies, which included a total of 214 newlywed couples.
As part of the studies, the couples were required to complete a daily diary for 14 days. Each day, spouses were asked to report whether they had engaged in sexual activity with their partner, as well as how satisfied they were with their sex life.
Couples were also asked to rate their relationship satisfaction, marital satisfaction, and partner satisfaction on a daily basis.
Additionally, the marital satisfaction of each couple was analyzed at study baseline and 4-6 months later at a follow-up assessment.
Stronger sexual afterglow linked to greater marital satisfaction
During the 14-day study period, couples reported having sex on an average of 4 days.
Not only was sexual activity associated with same-day sexual satisfaction, but also the researchers found that a single act of sex produced an afterglow that persisted for 2 days.
This finding remained after accounting for a number of possible confounding factors, including age, gender, sexual frequency, personality traits, and length of relationship.
On looking at martial satisfaction, the researchers identified an overall decline between study baseline and the follow-up assessment.
However, they found that couples who reported a stronger sexual afterglow were more likely to report greater marital satisfaction 4-6 months later, compared with couples with a weaker sexual afterglow.
Meltzer says the study findings are important, as they support previous research suggesting that sex plays an important role in partner bonding.
"Our research shows that sexual satisfaction remains elevated 48 hours after sex. 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."