According to a 2017 study in the journal Hormones and Behavior, the love hormone may not be all lovey-dovey. Oxytocin—released during sex and other intimate moments, it's also known as the "cuddle chemical"—may play a couple of different roles in romantic relationships. One theory is that oxytocin has to do with the honeymoon stage of a relationship; it's released early on in and helps two people bond. A second theory suggests that the hormone is released when there are perceived threats in a relationship.
In an effort to reconcile these findings, researchers from Norwegian University of Science and Technology (NTNU) and the University of New Mexico, proposed a new theory: That the brain releases oxytocin when "cues of relationship vulnerability combine with emotional engagement in the relationship," they write. In short, oxytocin may actually be a "crisis hormone."
The research team executed two studies to test their hypothesis. In one, 75 American couples were asked to provide samples of saliva before and after completing an open-ended writing task, which asked participants to analyze how their partners reveal—or how they wish their partners would reveal—they accept and connect with them. Researchers also measured how invested the partners were in each other by analyzing their answers in a questionnaire.
A second study, this time featuring 148 Norwegian individuals, had similar procedures. The main difference was that the Norwegian study did not include participants' romantic partners, and the subjects had to guess how invested they thought their partners were.
The results, however, were the same across both samples: "Consistent with our predictions, increases in oxytocin across a thought-writing task were predicted by high levels of individuals' own relationship involvement, but also by low levels of partners' relationship involvement," the study states. "Accordingly, the difference or discrepancy between self and partner involvement was a significant predictor of oxytocin change in both studies. This pattern was upheld in both male and female subjects."
In other words, study co-author Andreas Aarseth Kristoffersen, a psychology research assistant at NTNU, said in a statement, "When people notice that their partner is showing less interest in their relationship than they are, the level of this relationship-building hormone increases." As a result, people are motivated to do something about the perceived threat.
Nick Grebe is the lead author on the study and a PhD student in psychology at the University of New Mexico. "Most people assume that having higher OT [oxytocin levels] is a desirable thing—I mean, you can buy nasal sprays of the stuff on Amazon," he tells Broadly. "But, high OT doesn't necessarily mean you're better able to experience 'love' or personal satisfaction with your relationship—it could also mean there's a need to take care of a bond.
"We argue that elevated OT isn't necessarily a sign that everything is going well in a relationship," he continues. "It may be the case that it corresponds both to being highly involved, and being with a partner who doesn't meet your desired level of investment."