Oxytocin is a powerful hormone that acts as a neurotransmitter in the brain. It plays an important role in reproduction, initiating contractions before birth as well as milk release. And it is thought to be involved in broader social cognition and behavior, potentially ranging from mother-infant bonding and romantic connection to group-related attitudes and prejudice. The hormone is produced in the hypothalamus and released into the bloodstream by the pituitary gland.
Oxytocin has been called "the cuddle hormone" or "the love hormone" due to its association with pair bonding. It appears to help reinforce the early attachment between mothers and their infants, as well as the bonds between romantic partners. Animal research has connected oxytocin (along with another hormone, vasopressin) with the lifelong pair-bonding of prairie voles, and scientists have reported increases in oxytocin levels following orgasm in humans. There is also evidence that increases in oxytocin may encourage prosocial behavior, though not all studies have found these positive results, and some experts have undercut the idea that the hormone is a “trust molecule.”
In addition to infant-mother interactions (namely, when an infant suckles at a mother’s breast), a variety of behaviors may increase oxytocin, including hugging, cuddling, and having sex. Oxytocin can also be delivered through nasal spray, although the effects described by those selling these sprays may not be reliable.
Yes. Oxytocin is linked to the movement of sperm and the production of testosterone in men. Research suggests that it is increased following orgasm in men as well as women.
Importantly, oxytocin is one of various hormones that play a role in behavior, and its potential connections to psychology appear to go beyond love and prosociality. For all its apparent positivity, oxytocin may have a dark side—or, more accurately, it plays a more complex role in human behavior than is commonly thought. As a facilitator of bonding among those who share similar characteristics, the hormone may help set in motion preferential treatment of in-group members relative to those outside one’s group.