Watching his wife in agony as she was giving birth, Pavel Goldstein didn't know what to do.
"All I could think was, 'What can I do to help her?' " the postdoctoral pain researcher recalled. "I reached for her hand and it seemed to help."
He knew that couples can calm each other down, synchronising their breath and even brainwaves and heartbeats, just by being in each other's presence (it can also happen when people sing together or watch a movie together).
Researchers also know that skin-to-skin touch not only provides comfort, it contributes to the development of premature babies and helps to regulate their stress response.
But, could something as simple as touch really decrease pain? And, if so, how?
"I wanted to test it out in the lab," he said.
So he and a couple of colleagues at the Cognitive and Affective Neuroscience Lab at the University of Colorado recruited 22 long-term, "in-love" couples and put them through a series of "mild heat pain" experiments while monitoring their heart and breathing rates. In the experiments the couples were instructed to either hold hands, sit side-by-side without physical contact or were put in separate rooms.
The subjective pain ratings were lowest when the partners held hands and highest when they were separated.
Their heart and breathing rates also synchronised when they were in the same room together, but when pain was introduced, they only stayed in sync if they were touching; if one was subjected to pain and the partner couldn't touch them, they dropped out of sync, returning again if they were allowed to hold hands.
"It appears that pain totally interrupts this interpersonal synchronisation between couples," Goldstein said. "Touch brings it back."
Two aspects of the "well-designed" study stood out, said Lorimer Moseley, a professor of neuroscience and the chair in physiotherapy at the University of South Australia's Sansom Institute for Health Research.
"We have so many detectors in our skin that will give us a wide range of information about what is happening," he said, "and when you have touch there is quite a distinct pattern of sensory input that occurs in most of us."
While "tragically there are exceptions", for most of us that sensory experience is interpreted in the context of how parental touch as babies made us feel "highly safe", Moseley explained
"There was some really interesting work done on newborn touch and it having long-lasting effects in how you respond to touch later in life. The nervous system codes that distinct pattern of touch – human-to-human touch."
He adds that the new study, published in the journal Scientific Reports, highlights one of the most "exciting discoveries" in recent pain research.
"It was not that long ago that people thought pain was the signal that was sent from the body to the brain," Moseley said. "We now know that pain is a conscious event that serves to protect you, so if you have any safety cue at all it will reduce pain – if it's an effective safety cue. And that's a really potent safety cue having somebody who loves you and who you love holding your hand during a situation where you're getting a lot of danger cues from your body.
"Ultimately pain will depend on the balance between your danger cues and your safety cues. I think the most exciting discovery in pain in the last 20 years is that we can change pain with a whole range of danger and safety cues."
The causes of pain are hugely varied and he emphasises pain is very real and notes that those in the experiment did not experience "persistent pain".
"My research career has been spent engaging in that space – how do we reassure people that we know the pain is horrible and it's a system that serves to protect our body?" Moseley explained. "But what we also know is that there are a lot of people walking around – I'd say there's 3 million Australians walking around with persistent, horrible pain that's not very well explained by something wrong in their body but it is very well explained by the wide mix of danger cues and safety cues."
Regardless of the cause of the pain, working with these cues can help provide some relief.
"This should help people rethink what pain is," Moseley said. "It's a protective response and if you've got any information telling your brain that the need to take protective action has been reduced, for example you've got a loved one who's in it with you, sending powerful sensory cues through your skin, through a system that is gobsmackingly complex and fearfully and wonderfully effective, so don't underestimate the power of care and caring touch. It's a powerful thing."
This article originally appeared in The Sydney Morning Herald & was written by Sarah Berry.