There's an estimated 18.6 million mobile phone users in Australia. That's 89.9 per cent of the country's entire population with a mobile phone in their pocket this very second.

Data from Roy Morgan research says that is up 0.7 per cent on a year ago and up 2.1 per cent from two years ago.

The urge to check your phone is constant, Charles Sturt University (CSU) School of Psychology's Dr Keith Harris said.

'Have you missed a call? How many people liked or commented on your last social media post? What was that beep your phone just made?'

They're all real concerns for many people, Dr Harris said, and it has resulted in an often-used term these days - NOMOPHOBIA or NO MObile PHone PhoBIA.

But, Dr Harris believes it is not fear that's driving people, it's "smartphone stress".

"It's the stress of having to be constantly connected to people," he said.

IN OTHER NEWS:

"People have developed this feeling where if people tried to reach them, or they couldn't get them, or something was going on and they missed out. That's a negative thing and it's giving them an extra form of stress.

"They feel an obligation to always have their phone with them, to be connected to people, to respond quickly to text messages, to pick up the phone if someone calls you."

CSU has conducted a number of studies into smartphone stress, and data shows age and sex don't matter, but those with underlying anxiety are more impacted.

"Those people seem to react much worse to the smartphone connectivity stress," Dr Harris said.

"It looks like smartphones are maybe exacerbating anxiety symptoms in people, people who are already a bit vulnerable to anxiety."

Dr Harris understands why so many schools are choosing to ban students from using their phone during the day.

"Even if they're enjoying the lesson of the day, in the back of their mind they're wondering - did somebody like their picture? Did somebody else do something that they need to react to?," he said.

"It's hard to see why having phones there is going to be a good thing."

He even sees it in his own psychology lectures at university with students being less attentive and retaining less information if they're using their phones.

"It's a better relationship that we have and we get better outcomes when everybody is paying attention or involved," Dr Harris said.