Nestled among brightly coloured beanbags and cushions on the floor of an airy room in a large Cotswolds country house, seven young men and women in their 20s and 30s around me gaze into mugs of milky tea.
Draped in fashionable sportswear they look fresh-faced and, frankly, like every and any other Millennial Briton today, writes Eve Simmons for The Daily Mail.
But they speak of months, sometimes years of pain, desperation and self-destruction that eventually led them here – to Gladstones, a private addictions treatment centre, where they are undergoing intensive treatment for a very modern but increasingly common addiction: social media.
As the first journalist to be invited inside a four-week programme for internet misuse, I heard how apps and internet sites that millions of us use simply to connect with friends and up-to-date with current events have derailed and almost destroyed lives
And the problem is growing: admissions to Gladstones social media rehab programme have shot up almost 100 per cent in the past three years, as more people fall victim to the all-consuming online world.
A 28-day detox and primary care course costs £11,800 at Gladstones, which is recognised by all the major health insurers.
I meet Suzie, a 32-year-old mother-of-two from Berkshire, who was forced to confront her online addiction during a family holiday to rural Wales.
With limited internet reception, she began to suffer full-blown panic attacks, even refusing to play with her two children, aged five and eight, for what she describes as fear of missing out.
At the time, Suzie was averaging ten Facebook posts and four hours of solid tweeting each day.
She tells me:"If I had a thought, I would tweet it rather than say it to my husband. For the entire two-week holiday, I had to physically sit on my hands the whole time to stop me feeling so anxious.
"I was pacing back and forth between rooms in the cottage. The only thing that calmed me down was reading my Kindle."
It was the climax of two years of social-media obsession which began as part of her work in marketing. As Suzie's business grew, so did her reliance on her social-media presence.
"I told everyone that I needed to be contactable all the time for my business," she admits, "so I'd sit on Twitter and Instagram for entire evenings, ignoring everyone and tell them it was work.
"The kids would say "Mummy, look at what I did at school" and I wouldn't look up from my phone. I was so immersed in it that I didn't even feel guilty."
She describes the terror of going cold-turkey and seeking professional help – at the demand of her despairing husband – and was referred by her GP to Gladstones.
"It was terrifying," she says. "I had very dark periods where I wouldn't sleep for nights on end because of the panic.
"The more I realised that it was causing my anxiety, the less I wanted to use it. I knew I had to do something for the sake of my mental health."
During group and individual therapy sessions at Gladstones, Suzie and the other patients are learning to manage their compulsions through practical methods such as identifying 'triggers' that cause them to throw themselves into social-media use, and by keeping a journal and planning their daily activities, hour- by-hour.
After four weeks in rehab, Suzie's anxiety has reduced to a flutter and she's sleeping better than ever before.
Switching off is a must for patients at Gladstones. On entry, everyone must forfeit electronic devices, just as a prisoner might give up substances or sharp objects. "I tried to hide my phone down my bra," admits Grace, 17, from Bristol, whose compulsive Instagram searches for 'thinspiration' led to her anorexia.
Another patient, 22-year-old John from a farming village near Cheltenham, admits that he fought with his father, physically, when he tried to take away his phone.
"I had my dad's credit card for emergencies, and would spend at least £100 a day on gaming sites or buying things off people I met in Facebook groups, and racked up a £50,000 bill," he says.
"One day Dad stormed into my room and found me in front of the screen. He pulled me away from the computer. I wouldn't have it. Punches were thrown."
Shortly before discharge, individuals are 'reintroduced' to the internet: five minutes of phone access, twice a week, with progression to 20 minutes of supervised computer access.
By this point, they've learnt the emotional tools to manage compulsive behaviour and are able to resist temptation.
How Instagram left me unable to function
Sabrina Greenberg, a 31-year-old app developer from London, turned to Instagram for exercise inspiration. Sabrina – who's "never been more than a size 10" – says: "My new Instagram friends said I must go refined sugar, grain and dairy-free, while doing three intense exercise sessions each week at the gym
"Within two months, I became obsessed. At work, I'd scour images of "healthy" food and check my Instagram comments at least 15 times a day."
Six months later, she was surviving on raw vegetable soup and had shed almost two stone, leaving her dizzy, weak and 'unable to function'. She tells me: "It was incredibly competitive. If you could cut out the most from your diet, you'd get appreciation in comments, which made me feel good but kept me very ill."
Not only was Sabrina's Instagram habit bad for her health, there were financial implications, too.
"I was spending £100 a week on meal-replacement powders, protein powders, matcha tea supplements – whatever I thought would make me "well".' After Sabrina's mother intervened, she deleted Instagram. But despite regaining the weight she lost and engaging in counselling sessions, her relationship with food remains tainted.
"I'm still not eating in the way I used to. I've forgotten how," she says. "But I now know who my real friends are."
A new addiction
As a prolific tweeter myself, I often worry about the effects of my 20-minute morning session. It's the first thing I do when I wake up and the last thing I see before I go to bed, and has even caused rows with my boyfriend when he accuses me of ignoring him. In a recent attempt to curb my social-media habit, I downloaded an app called Moment, which keeps a track of my screen time. I'm online for just over three hours per day, roughly twice the UK average. Does that mean I am addicted?
I ask consultant psychiatrist Dr Henrietta Bowden-Jones, who runs a private internet addiction clinic at the Nightingale Hospital in London. "The difference with addicts is that their internet use becomes all-consuming and affects their daily life in a harmful way," she says.
"With online gaming or gambling, we see similar compulsive personality types to that which we see in substance addictions, but with social media it's different. These people are not prone to addiction. They are using it as a distraction, a sort of bandage, to numb emotional pain."
She adds: "A person might be very insecure, which leads them to develop a terror of missing out. Or they may gorge on images and facts in a bid to make them feel better about themselves."
The insidious impact
Social media has actually been around since the 1970s, beginning with a programme called Talkomatic, which provided an early version of a chat room for students at the University of Illinois. But the watershed moment came with the 2004 launch of Facebook, which now has more than two billion monthly users.
To most, it is harmless, connecting users with friends and family. However, in recent years, disquiet has been growing about the insidious impact its relentless stream of information, images, text and video is having on our mental health.
In December last year, Facebook's former head of growth, Chamath Palihapitiya, blamed the social-media site for "ripping society apart" and admitted that he felt "tremendous guilt" for unleashing what he referred to as "the beast" on an otherwise civilised society.
And last month, leading 'techsperts' from Google and Facebook launched a new initiative, the Centre For Humane Technology, which will warn global educators, politicians and other global influencers of the "technology platforms that are hijacking our minds". The extreme end of the problem can be witnessed at addiction centres such as Gladstones up and down the UK.
So what about the scale of the problem? While UK figures for internet addiction incidence aren't yet available, Dr Bowden-Jones has seen a stark rise in cases. "When we trialled an internet clinic," she tells me, "we were bursting at the seams."
In an effort to establish the true impact of growing up online, the Children's Commissioner for England, Anne Longfield, conducted interviews with 32 eight- to 12-year-olds and published her findings in a report last month.
She says: "There's an avalanche of pressure and anxiety when children hit secondary-school age, much of which is a result of social media. Pressures combine to increase the risk of misuse. There's a very sinister aspect too. Lots of the children edit pictures of themselves, perhaps receive disturbing images, and were overwhelmed with up to 500 friend requests.
"The apps encourage you to stay online, which feeds insecurity and anxiety about not being able to switch off."
So what can be done? Former addict Suzie says: "The key is to deal with the emotional issues driving the addiction, and then find an activity you enjoy that doesn't involve the internet.
"These days, I run my online businesses without getting obsessive. It's all about moderation and not feeling as though you have to be more present on the internet than you are in your real life.
"There are so many pleasures that don't involve the internet. Since I've changed my habits, I read 52 books a year, I sleep better and most of all I am far, far happier."
Some personal information has been changed to protect patient identity.
FIVE WARNING SIGNS
Lead clinical psychologist Dr Caroline Rond of Gladstones Clinic offers a checklist for internet addiction.
If you said 'yes' to any of these in the past six months, or your online behaviour has escalated, you may have a problem…
1. Relationship in trouble?
Has your internet use adversely affected relationships with partner, family, friends or colleagues?
2. Are you time wasting?
Do you lose track of time while online (at home or work) and spend longer than you'd like scrolling?
3. Are you on the edge?
Are you overwhelmed with feelings of irritation/ frustration if you try to cut back or someone challenges you about your use? Do you spend time thinking about your next online session?
4. Do you feed the beast?
Do you feel the need to use the internet for increasing amounts of time to achieve satisfaction?
5. Is it an escape?
Does time online make you feel better? Do you use it to distract yourself from depression, anxiety or guilt?