Oxytocin is widely known as the "love hormone" due to its beneficial role in social bonding and sexual reproduction. According to a new study, however, oxytocin isn't all about the good times; it is also at play during periods of relationship insecurity.

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Researchers have found that the 'love hormone' oxytocin increases in response to relationship insecurity.

Researchers found that when an individual feels that their partner is losing interest in their relationship, levels of oxytocin increase.

First study author Nicholas M. Grebe, Ph.D., of the Department of Psychology at the University of New Mexico in Albuquerque, and colleagues recently reported their findings in the journal Hormones and Behavior.

Oxytocin is a hormone secreted by the pituitary gland, a pea-sized structure in the brain that is situated just below the hypothalamus.

The role of oxytocin is vast. Not only is the hormone responsible for inducing contractions during childbirth, but it is also involved in mother-child bonding and sexual arousal. Its duties, however, may not end there.

The study from Grebe and colleagues indicates that the brain releases oxytocin in times of relationship crises, possibly in an attempt to "fix" the relationship.

Oxytocin tries to 'take care' of a relationship

The researchers came to their findings by enrolling two groups of adults. One group was comprised of 75 couples from the United States, while the other group consisted of 148 individuals from Norway who had a romantic partner.

"Participants in the study were asked to think about their partner and how they wish their partner would connect with them in the relationship," explains study co-author Trond Viggo Grøntvedt, Ph.D., also from the Department of Psychology at the University of New Mexico.

Subjects' oxytocin levels were measured before and after the thinking task.

The team found that participants who felt a strong personal investment in their relationship demonstrated an increase in oxytocin levels, which further supports oxytocin's role in social bonding.

However, the researchers uncovered an interesting result when assessing partners' oxytocin levels simultaneously.

Among couples in which one partner was more invested in the relationship than the other, the more invested partner showed a greater increase in oxytocin levels when they thought about their relationship.

The researchers suggest that this heightened increase in oxytocin may be an attempt to rebuild a relationship bond.

"What's implied here is a statement about what oxytocin is doing: it's perhaps fostering attention to and motivation to 'take care of' the relationship," says study co-author Prof. Steven W. Gangestad, also of the Department of Psychology.

Oxytocin may not be able to 'fix' doomed relationships

However, the team found that there is a limit to oxytocin's relationship-fixing efforts. Among couples whose relationship was heading toward breakup, the partner who was most invested did not show a significantly heightened increase in oxytocin levels.

Overall, the authors believe that their findings support the "identify and invest" theory in relation to romantic relationships, whereby the brain identifies a vulnerable relationship and tries to strengthen it.

"We think that viewing oxytocin in this way can help us understand why it plays a role in other kinds of interdependent social relationships - new romances, mother-infant bonds, as two examples.

The idea is that emotionally salient relationships, especially when those relationships are vulnerable, are elicitors of the oxytocin system."

Nicholas M. Grebe, Ph.D.

Learn how oxytocin may increase the bond between a father and child.