When Suzie Blackwell hiked through the mountains of Patagonia, she stayed at a camp with no Wi-Fi. "It was really noticeable how friendly people were," she says. "Everyone was very open and approachable, and really engaged when you sat down and talked."

Blackwell, who uses a work mobile as well as her own smartphone at home in Sydney, found it liberating. With no prospect of connecting to the internet, people made personal connections the priority.

"It's so much easier to make eye contact when people aren't looking down at their phones," Blackwell says. "I struck up some friendships and had really good conversations with people because they weren't using their phones. There was nothing to distract them."

Since Apple launched the iPhone in 2007, smartphones have saturated society. More than 80 per cent of Australians have one; only 4 per cent of 18 to 34-year-olds don't.

We use them to email, take photos, check social media, listen to music, surf the internet, find directions, watch movies. We even use our smartphones to use our smartphones less, installing apps that monitor and limit our activity.

The names and popularity of such apps reflect a growing desire for time out from the technology that was supposed to make life easier. BreakFree. QualityTime. Pause. Moment.

Alarmed by how often he and his wife were "zoning out on the couch on our phones", US app developer Kevin Holesh​ built Moment to let people track their use, set daily limits and deter them from using their phone.

With a tagline of "Put your phone down and get back to your life", it has been downloaded 2.5 million times in less than two years.

"There's a wave of people who are sick of using their smartphones too much," Holesh says. "People are generally using their phone about twice as much as they estimate."

Rich Ling, professor in media technology at Singapore's Nanyang Technological University, is a leading expert on the social consequences of mobile communication. Smartphones "make us individually available to one another", he says, helping us co-ordinate busy lives and encouraging social cohesion within small groups.

But they have their downsides. Ling notes it's harder to operate socially if we forget our phone or the battery dies. And given the expectation that we should be accessible at all times, he says we are "in a small way shirking our social responsibility" if we are not.

The pressure to be constantly available and responsive on social media can cause depression, anxiety and decrease sleep quality for teenagers, according to University of Glasgow researchers.

It's not just teens feeling that way. Thirty per cent of those surveyed for the latest EY Digital Australia: State of the Nation report said their smartphone or tablet negatively affected their sleep or stress. Thirty-one per cent felt "addicted" to their device – a figure that rose to 46 per cent among 18 to 34-year-olds. They are a major contributor to the breakdown of the work/life divide; one survey found working from smartphones and tablets adds two hours to the average working day.

And still we are loath to switch them off. There's even a word – nomophobia – for the fear of being out of mobile phone contact.

Nomophobia is part of the bigger problem of internet addiction, says Dr David Greenfield, assistant clinical professor of psychiatry at the University of Connecticut School of Medicine and founder of the Center for Internet and Technology Addiction.

He says going online is like playing the pokies – "You never know what you're going to find, and you never know how good it's going to be". The smartphone's ability to give you want you want instantly, and its incessant notifications, make it especially hard to resist. Greenfield calls it "digital crack".

Primitive biological responses partly explain the allure of the technology. Like other types of dependence, internet addiction involves the neurochemical dopamine, which is related to reward-motivated behaviour.

"If you get a notification, your dopamine level goes up, and if you check it and it's really good it reinforces that dopamine hit with a little bit more," Greenfield says. "If something's pleasurable you're more likely to repeat it. When the pleasure is variable, you're more likely to do it in a compulsive manner."

Greenfield says the primary hit comes in anticipation of the reward. "That's why one of the things we tell our patients is to turn off the notifications, because the notifications are what drive them."

The prevalence of internet addiction ranges from 3 per cent to 12 per cent of users, Greenfield says. He has treated hundreds of patients whose relationships, work or study suffered, or who ran into financial or legal trouble. Because digital technology is almost impossible to avoid, treatment focuses on mindful or controlled use.

Greenfield points out that, unlike other forms of media, there are no natural boundaries to internet consumption, no markers for the beginning and end. "There's always another link or another story or hypertext to another piece of information, so the brain feels as though nothing is ever finished and that makes it that much more compelling."

So compelling that the average person looks at their smartphone 221 times per day – an average of once every 4.3 minutes – a study by Tecmark in Britain says.

Researchers are increasingly looking at how smartphones, as a source of infinite distraction, interfere with our mental functioning and social relationships.

In the US, studies have found that iPhone separation anxiety has a negative effect on our cognitive ability and that media multitasking – something smartphones enable to an unprecedented degree – has been associated with symptoms of depression and social anxiety.

The late Clifford Nass, who was a psychology professor at Stanford University, said chronic multitaskers are terrible at a range of cognitive tasks including – funnily enough – multitasking. He described them as "mental wrecks".

"People who multitask all the time can't filter out irrelevancy," Nass told NPR. "They can't manage a working memory. They're chronically distracted."

The quality of our social interaction is also suffering; research at the University of Essex found the mere presence of a mobile phone in the room inhibits the development of interpersonal closeness and trust.

Our phones remind us there's a world beyond our immediate social sphere; that something, somewhere, is happening without us. Checking your phone during a social encounter is the equivalent of talking to someone while looking over their shoulder to see who else is in the room.

Ling says we check our phones automatically, without thinking. We use them to fend off boredom at the checkout or waiting for a bus. "It's a quasi-habitual response that plays on a strong desire to be socially connected," he says. At the same time, it "pulls us out of the public sphere. It is an easy out if ... you don't really want to engage".

So even though we're physically present, our attachment to our phones means we're often mentally absent. And it's undermining our capacity to have meaningful conversations, says Sherry Turkle, professor of the social studies of science and technology at the Massachusetts Institute of Technology.

In her latest book, Reclaiming Conversation: The Power of Talk in a Digital Age, she argues digital interaction is harming our ability to converse face to face and reducing our capacity for empathy. "I feel we have now created an environment that will distract us to distraction," she told The Guardian. She recommends banishing devices from the dinner table, the car, the kitchen – "sacred spaces for conversation".

Sydney psychologist Jocelyn Brewer says when you have a healthy relationship with technology, you don't have to force yourself offline to find peace. She created the Digital Nutrition framework to promote balanced, mindful use of technology, so we can "keep it as a really great servant and not let it become our master".

Brewer says our memories and creativity can be affected by the digital onslaught. With one study equating the amount of information we receive each day to 174 newspapers – and that was before smartphones – Brewer says "we're letting important, emotionally salient information slip through".

There is value from having time out from the information overload and reconnecting to our internal world, she says. "Boredom is recognised as a gateway to creativity, so if we can't be alone with ourselves and are unable to tolerate a lack of stimuli then we actually block out the opportunity to feel boredom and the possible creative thinking that comes out of that."

Holesh is now working on a Moment "boot camp", giving people tools to cut their smartphone use. But he says no app can force you to put down your device. "You have to want to use your phone less."