The science behind the perfect hug, from pressure to duration

Researchers have revealed the science behind the perfect hug. (Getty Images)

In these coronavirus-impacted times when social distancing rules are keeping so many of us apart, we’re all craving a good hug.

And while we’d take just about any hug right now, science has been busy figuring out what actually makes the perfect hug.

The cuddle testing squad – in fact, a team of scientists from Japan’s Toho University – measured the calming effects on infants of hugs of varying pressures and those given by strangers compared with their parents.

By monitoring the infant heart rates and using pressure sensors on the adult's hand, the researchers assessed the baby’s reaction to being simply held, receiving a hug with medium pressure, and what they called a “tight hug”.

The results, published in the journal Cell, found that babies were soothed more easily by a hug with medium pressure, than they were when they were just being held.

But the calming effect decreased when they were given a “tight” hug.

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When it comes to the effects of the different hug givers, unsurprisingly for infants older than 125 days, the calming effect was greater when receiving a hug from a parent than from a female stranger.

Therefore, researchers suggested the perfect cuddle requires medium pressure and should be given by a parent.

The researchers kept the length of the hug to 20 seconds as “it was almost impossible to avoid infant’s bad mood during a one-minute or longer hold or hug”, they shared in their paper.

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Parents can feel the benefits of baby hugs too! (Getty Images)

Turns out we don’t grow out of the benefits of comforting hugs either.

The research also revealed that parents also exhibited significant signs of calmness while hugging their child.

Both parents and infants both showed an increase during a hug in what's known as the R-R interval (RRI) on an electrocardiogram.

This is the time between a particular waveform that measures electrical activity of the heart and the increased time indicates a slowed heart rate.

“The infants older than four months old showed a high increase ratio of heartbeat intervals during hugging by their parents than by female strangers,” explains first study author Sachine Yoshida, of Toho University, in a release.

“Parents also showed a high increase ratio of heartbeats intervals by hugging their infants. We found that both infants and parents come to relax by hugging.”

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Though hugs are thought to release a hormone called oxytocin, also sometimes referred to as “the cuddle or love hormone”, researchers believe the time period of their hug experiment was too short for this to play a role.

They therefore believe their research could be the first time the physiological impact of hugging infants has been measured.

They hope their work could help to improve knowledge of parent-child bonding and child psychology.

“Even though infants cannot speak, they recognise their parents through various parenting methods, including hugging, after four months old at latest,” Yoshida adds.

“We hope that knowing how your baby feels while being hugged could help ease the physical and psychological workload of taking care of infants too young to speak.”