February 13, 2012
Oxytocin Levels Predict Longevity of Love Affairs
New research links levels of the “cuddle hormone” with falling, and staying, in love.
A team of researchers led by Inna Schneiderman of the Gonda Brain Sciences Center of Israel’s Bar-Ilan University have just published a study examining the role oxytocin, commonly called the “cuddle hormone,” plays in the early stages of romantic relationships. While differentiating cause and effect is tricky, the researchers find a strong link between lasting relationships and high levels of the hormone.
Oxytocin, as they note in the journal Psychoneuroendocrinology, promotes trust, bonding and attachment — between adults, and between parents and their offspring. (Less appealingly, it can also promote ethnocentrism.)
Schneiderman’s study featured 163 people in their early to mid-20s, 120 of whom had recently initiated a love affair. (On average, their relationship had begun 2.5 months prior to testing.) All had their blood tested for oxytocin levels.
“New lovers had substantially higher plasma levels of oxytocin, as compared to non-attached singles,” the researchers report. “These findings are consistent with those reported for other mammals, particularly monogamous rodent species in which oxytocin has shown to play a critical role in the formation of pair bonds.”
Since they didn’t measure oxytocin levels before the relationships began, Schneiderman and her colleagues can’t say for certain whether they increased during the romantic bonding process, or whether “individuals with high levels of oxytocin are more likely to fall in love.”
Six months later, the researchers located 54 of the 60 couples and retested the 36 who were still together. Their oxytocin levels were still at the same high level, which either explains or reflects the fact they were still happily bonded.
Perhaps the most striking finding: “Couples who stayed together showed higher oxytocin levels at the initial period of romantic attachment” than those who broke up. “These findings suggest that oxytocin in the first months of romantic love may serve as an index of relationship duration,” the researchers write.
This brings to mind the intriguing possibility of oxytocin-enhanced relationship repair — couples counseling augmented by hormone injections. In previous studies, raising people’s oxytocin level (via nasal spray) “was found to increase bonding-related behavior, including … trust and empathy,” the researchers note.
That said, the study raises a chicken-and-egg question, since it isn’t clear whether high oxytocin levels lead to more closeness or whether romantic behavior increases oxytocin levels.
During their initial testing, the lovers were interviewed about their relationship and observed while talking together. The researchers found a correlation between oxytocin levels and their level of “interactive reciprocity” — which is to say, their responsiveness to one another and tendency to engage in affectionate touching.
“Oxytocin is known to function as a bio-behavioral feedback loop,” the researchers note, adding that “research in mammals showed that more touch and contact increased oxytocin receptor density.” This suggests loving couples may get into a positive routine in which “higher levels of reciprocity and touch” allow them to maintain elevated oxytocin levels, sustaining their feeling of emotional connection.
So couples may not need artificial administrations of the cuddle hormone; they may just need to cuddle.