Those corny old love songs might be on to something after all. Scientists say the touch of a partner’s hand can both relieve pain and restore the physiological connection that pain interrupts. They published their findings in the journal Nature Scientific Reports.

Social animals love living in synch. Fireflies flash at the same time; predators prowl in unison toward their prey. Friends walking together unconsciously fall in step. Choir members’ hearts beat as one when they sing. Scientists believe these rhythmic connections may have developed to strengthen the community and the individual, making both more resilient and more likely to survive.

The same may be true of touch, a force so powerful that animals in experiments consistently choose it over food.

Pain researcher Pavel Goldstein of Cognitive and Affective Neuroscience Lab at CU Boulder had both these ideas on his mind in the delivery room as his wife gave birth to their daughter.

"My wife was in pain," he said in a statement, "and all I could think was, 'What can I do to help her?' I reached for her hand and it seemed to help," he recalls. "I wanted to test it out in the lab: Can one really decrease pain with touch, and if so, how?"

Goldstein and his colleagues set up a simple experiment, recruiting 22 long-term heterosexual couples. They brought the couples into the lab and hooked each person up to instruments to measure their heartbeat and breath. Some of the couples sat together, holding hands; some sat slightly apart; and some were seated in separate rooms.

Then the researchers zapped each woman’s forearm with a low amount of heat, just enough to cause pain, for 2 minutes.

Before the pain began, couples who sat in the same room experienced a concrete physiological connection. Their heartbeats and their breathing rates synched.

Then the pain came, and that connection went away—unless they were holding hands.

The same physical contact was also associated with decreased pain levels. Women hurt less when the men they loved took their hands.

The researchers can't say for sure why this is the case. "It could be that touch is a tool for communicating empathy, resulting in an analgesic, or pain-killing, effect," Goldstein said.

This study had its limitations. It was very small, and all the participants were young (23–32 years old). The experiments didn’t explore what would happen to men in pain, nor did they consider the question in same-gender couples. More research is certainly needed to validate these results. But for now, if someone you love is hurting, well, you know what to do.