A loving mother works her magic just as well with soothing words as she does with hugs, scientists have learned.
Merely talking to mum on the phone was enough to release a stress-busting "cuddle hormone" in a group of anxious children, a study showed.
Hearing their mother's voice had virtually the same effect as receiving a big, warm hug.
In both cases, levels of oxytocin rose sharply in the children.
The hormone is well known for its ability to forge social emotional bonds, especially between lovers and mothers and their babies.
Scientists in the US carried out the study by deliberately placing a group of 61 girls aged seven to 12 under stress.
The children were asked to make an impromptu speech and then solve a series of maths problems in front of strangers.
Tests confirmed that the task sent the children's hearts racing and their levels of the stress hormone cortisol soaring.
The children were then split into three groups, one of which was comforted by having physical contact with their mothers.
A second group spoke to their mothers on the phone, while a third was shown an emotionally neutral 75-minute film.
The results of the study came as a surprise to the researchers.
Leading scientist Dr Leslie Seltzer, from the University of Wisconsin-Madison, said: "The children who got to interact with their mothers had virtually the same hormonal response, whether they interacted in person or over the phone.
"It was understood that oxytocin release in the context of social bonding usually required physical contact. But it's clear from these results that a mother's voice can have the same effect as a hug, even if they're not standing there."
Saliva and urine tests were used to measure cortisol and oxytocin in the children.
The researchers found that as oxytocin went up, levels of cortisol faded away, showing a reduction in stress.
Furthermore, the effect was long-lasting.
"It stays well beyond the stressful task," said Professor Seth Pollak, another scientist from the University of Wisconsin-Madison Child Emotion Lab. "By the time the children go home, they're still enjoying the benefits of this relief and their cortisol levels are still low.
"That a simple telephone call could have this physiological effect on oxytocin is really exciting."
The findings are reported today in the Royal Society journal Proceedings of the Royal Society B.
Dr Seltzer is now investigating whether other forms of communication, such as text messaging, have an effect on oxytocin. She also hopes to expand the research into animals.