For the most part, Liz Spikol’s videos on YouTube come across as light-hearted and quirky. In one, she pinches her chin to demonstrate her weight gain; in another, she muses on what it meant for her relationship when she lost her libido. Yet Spikol, 40, executive editor and columnist of Philadelphia Weekly, is talking about what it’s like to live with bipolar disorder, a condition she has suffered from since her twenties.

Spikol is part of a growing movement of people who suffer from serious mental illness and are willing to talk honestly and publicly about their condition. She is articulate and successful, and this is part of the point. In books, lectures and blogs, Americans, particularly women, are gathering to fight the stigma of “the mad woman in the attic” and show they can live successful lives.

Now, this confessional trend is gathering momentum in Britain.

In London, a group of people who self-consciously refer to themselves as “mad” are getting together for a day-long festival on Saturday, aptly named Bonkersfest. It bills itself as a celebration of madness, creativity, individuality and eccentricity, “bonkers celebrations for everyone — bonkers or not”.

So Dolly Sen, 37, an artist and writer, will spend the day trying to screw a light bulb into the sky because “the world is dark enough as it is”. There will also be a moving padded cell, a de-normalisation programme, and performance art by Bobby Baker featuring seven adults dressed as frozen peas.

Does it sound a bit crazy? Well, that’s the point. “There’s a history of many artists and writers being diagnosed with mental illness,” says Baker. “People who were unusual and different used to be more celebrated and accommodated, but now there’s a tremendous amount of fear. I feel people like me have a sensitivity and creativity that is very valuable, as well as an enormous sense of humour about the whole thing.”

Bonkersfest was set up by the arts organisation Creative Routes, whose stated aim is to celebrate the creativity of mad people and campaign against discrimination. Certainly, many actors and comedians with mental health issues have talked about their problems. Ruby Wax, who has suffered from depression, will perform a monologue on mental health issues at the Edinburgh Festival in August. Stephen Fry has written about his experience of bipolar, and Hugh Laurie and Emma Thompson have admitted battling mental demons.

Yet for an ordinary person, without the protective glamour of celebrity, it can be much harder to talk about mental illness. “You feel ashamed,” says Sen. “It feels like something that should be hidden. Since I’ve been involved with Bonkersfest, my confidence has gone through the roof. It’s so empowering to be with people who understand you because they’ve been exactly where you’ve been, and you know they won’t judge you.”

Sen has certainly been in some dark places. When she started hearing voices at the age of 14, her life “stopped in its tracks”. Before that, she remembers doing well academically and playing football for her school, but once she became ill, she was taken out of class and offered no further education. For the next 15 years, she was on different kinds of medication and in and out of hospital in what she describes as a “horrible kind of life”. Eventually, the right medication was found, and three years ago, she was offered cognitive-behavioural therapy tailored to psychosis. “It has changed my life,” she says. “I still hear voices and get twinges of paranoia, but I am able to stall those thoughts.” Now she is studying film at university and feels in control of her life.

Baker refuses to say what her diagnosis is and prefers to call herself “bonkers”. “The trouble with labels is that people are very judgmental about those who are different,” she explains. She remembers when she decided to start talking more openly about her problems. “I had a show at the Barbican and thought I was established enough for it to be fine, but I heard a woman say she couldn’t get any of her friends to come because they didn’t want to see ‘some weird madwoman on stage’. I was shocked.”

For Spikol, the experience of talking and writing about her illness has been immensely powerful. “I got lucky with my editor,” she says. “Some people tell their employer about their problems and they get fired. I was asked to write a column. I was nervous about revealing what had happened to me, but the response has been so supportive, it has shown me it is worth writing about.”

Spikol’s symptoms started when she was 18. Initially, she suffered mainly from hallucinations. She was convinced there were cockroaches living in her mattress at university, so she slept on the floor. She managed to graduate, with a lot of support, but by the time she started her doctorate, she was too ill to continue. Eventually, she was given electroconvulsive therapy.

In one of Spikol’s more serious YouTube videos, you get a sense of what that must have been like. She holds up an adult nappy to demonstrate what she had to wear. Patients are also given mouth guards to stop them biting off their tongues. The treatment didn’t help, and it left her so profoundly disconnected from herself that she couldn’t even remember how to wash her hair.

Finally she was given medication that worked, and over the past 10 years, she has felt relatively stable and is in a committed relationship. “My previous relationships were unstable,” she says. “It’s hard for anybody to deal with somebody who is emotionally inconsistent. I went out with damaged people; it was like we found each other in the storm. For the past four years, I’ve been in a healthy, normal relationship. I met my boyfriend through friends, and because of my column, he already knew about my condition.”

She is less preoccupied with the labelling issue than many of the performers at Bonkersfest, and is happy to talk about bipolar disorder. She would rather focus on recovery, survival and being well. “I know some people feel that being mad is a gift to be proud of, but if somebody approached me and said, ‘I have a cure for bipolar disorder,’ I would take it right away. I don’t think the condition is an achievement, I think the way I live with it is an achievement.”

Ultimately, whatever the differences of the people within this movement, what they are all trying to do is reduce stigma, improve care and establish a more open conversation about mental illness — even if it means calling yourself bonkers and dressing up as a frozen pea.

Bonkersfest is on Saturday at Camberwell Green, SE5; bonkersfest.com