Mum's voice soothes stress, even by phone

13th May 2010 -- A kind word from your mum by phone may be as good as a hug in calming the frayed nerves of daughters, a new study indicates.

In the study, which involved 61 girls aged between seven and 12, researchers say a mere phone call from their mums helped reduce the stress levels of the youngsters.

Led by biological anthropologist Dr Leslie Seltzer, of the University of Wisconsin-Madison in the US, the research team set out to measure fluctuations of the stress hormone cortisol, as well as of the "comfort" or "cuddle" hormone oxytocin.

The girls, all volunteers, were suddenly placed in stressful situations. They were asked without warning to deliver a speech in front of a group of strangers, an exercise that can create stress in people of any age.

Then they were given difficult maths questions -- also in front of an audience. As expected, cortisol levels, known to increase with stress, rose significantly when measured in saliva soon after the stressful situation.

Seltzer and Dr Seth Pollak, a psychology professor at the university, then divided the girls into three groups.

The mothers of one group were on hand to hug and offer physical comfort to their daughters. Other girls were handed a telephone, with mum on the line. A third group watched an emotionally neutral film called March of the Penguins.

Researchers say the calming effect on the girls who were comforted by a hug or physical touch was more immediate, but that the stress hormone levels also quickly dropped in those who received soothing words from their mothers by phone.

For the girls who watched the film, cortisol levels were still considerably above normal an hour after their stressful experiences. Similarly, levels of the "cuddle hormone" oxytocin went up in girls who were hugged as well as those who received comforting phone calls, though not quite as fast in those whose mothers were not physically present.

Oxytocin levels were flat or low in the girls who watched the film. The hormone levels were tested in samples of urine collected at various times during the course of the experiment.

"It was [previously] understood that oxytocin release in the context of social bonding usually required physical contact," Seltzer says in a news release. "But it's clear from these results that a mother's voice can have the same effect as a hug, even if she's not standing there."

The relief from anxiety lasts, Pollak says. "By the time the children go home, they're still enjoying the benefits of this relief and their cortisol levels are still low," he says in the news release.

Gender differences in reacting to stress

The findings are published in the journal Proceedings of the Royal Society B, and they match a "tend and befriend" theory, explaining how stress regulation may differ between females and males.