It might sound bizarre, but she's experiencing ASMR – an autonomous sensory meridian response – and she's not alone.

There are now more than 13 million videos on YouTube dedicated to that "tingling" sensation, which ASMR artists give their audience through sound triggers, whispers, slow hand movements and close personal attention.

The acts performed in these videos can range anywhere from makeup tutorials to simulated medical examinations, haircuts, massages and towel folding tutorials. Those who experience ASMR can find a thrill in a squish or scratch, while those who don't are often left baffled.

"When I mention ASMR to people, the first thing they say is, 'That's weird'. I say to them, 'Well, do you think it's weird to listen to raindrops and waterfalls?' Regardless of the source, it's a sound that just calms you or releases stress in some way," Ms Pereira, 21, said.

"When it happens I think wow, it's crazy how the reaction [to the videos] takes over my entire body. It takes me to a relaxed state."

The popularity of the videos has skyrocketed in recent months, as has the mass of anecdotal evidence that suggests they are having a profound physiological and therapeutic impact on their viewers.

There are thousands of people who say ASMR has helped them with their insomnia, anxiety and depression but there is little robust, researched evidence to back up their claims.

Dr Giulia Poerio, who headed The University of Sheffield's world-first study into ASMR, called More than a feeling, puts this lack of evidence down to the fact that people who don't experience it can have difficulty even acknowledging its existence.

It's not known what percentage of the population experience ASMR and those who do may not realise what their visceral reaction is.

"The motivation for my research comes from the fact that I've experienced ASMR my whole life, but I didn't realise that it was something that other people also experience," she said.

"When I found out that it was a thing, I searched for research on the topic. I was looking and there wasn't anything at the time.

"The more I spoke to people about it, the more I realised that people who don't experience it find it really difficult to believe it's a real thing and they think it's somehow weird. I wanted to provide a test of whether it's a genuine experience and physiologically rigid."

Through her own research, Dr Poerio was able to identify a tangible connection between ASMR and emotional and physiological benefits in those who experience it.

Of her study's participants, those who experienced ASMR while watching the videos showed significant decreases in their heart rate (an average decrease of 3.14 beats per minute) compared to those who did not experience it.

They also displayed significant increases in positive emotions including relaxation and feelings of social connection, as well as increased skin conductance levels.

Dr Poerio says these findings demonstrate not only that ASMR is a legitimate experience, with a legitimate, physiological response, but that it also has the potential to assist those with mental health ailments.

"It's really clear just from looking beyond my community that people are using ASMR videos to help with insomnia, anxiety, depression and all those sorts of things," she said.

"Our research shows that ASMR, when people do experience it, has an emotional and psychological benefit that is comparable to other techniques such as mindfulness."

Fallon Cryer, a 35-year-old Chief Operating Officer from Brisbane, says she is one of those people.

Having discovered the YouTube phenomenon about two years ago, she now uses ASMR videos to help treat her insomnia and anxiety, listening to them particularly before bed to help her fall asleep.

"For me, [ASMR] artists trigger feelings reminiscent of childhood, particularly being mothered and cared for," she said.

"As an adult, our need to be cared for doesn't go away. But if you're 35 and anxious, no-one is going to tuck you in, stroke your hair and say nice things to you until you fall asleep ... unless you watch ASMR."

Recent research shows one in four Australian adults is lonely, and mental health is now the number one reason people see their GP.

Dr Poerio says that while ASMR videos have the potential to assist some people with their mental health, the fact that many do not experience ASMR at all puts limitations to how useful it can be.

"Our research suggests that people who didn't experience ASMR still felt more relaxed and had a reduced heart rate [after watching the videos]; just not as much as people who experience ASMR," she said.

"Unfortunately, what can also happen when you become over-exposed to ASMR content is that you become immune to it. So whether or not this could be used in the same way as mindfulness is really difficult to know because people can build up tolerance and it's not teachable in the same way mindfulness is."

She anticipates that further research into the subject will be done following the international interest in her study. Her published research is based on an online survey of 1,000 people and a study of 112 people, half who said they experienced ASMR and half who said they didn't.

"[We know] it certainly helps people a lot, and I think that's why it has become so popular."