Ruby Wax thought her career had reached rock bottom when she agreed to take part in the reality show Celebrity Shark Bait.

Yet she scraped the barrel even further when she dressed up in a corset as a ringmaster for the Sky1 circus show Cirque du Celebrite.

But she reveals that she did draw the line somewhere, despite an offer of more than £100,000 to go into the Celebrity Big Brother house.

“It was really, really hard to turn that amount of money down,” she confesses.

“But I would have ended up institutionalised if I’d gone in the Big Brother house. I would have ending up spending the fee on therapy.

“After 25 years of doing really interesting TV, I don’t think I can bend to this stuff. I couldn’t live with myself.”

Ruby, 60, is famous now for speaking out about her battles with depression and breakdowns.

For years she tried to cover it up, ironically once while making a show about mental health and interviewing people with schizophrenia, OCD, bulimia and bipolar disorder.

As she recounts in her latest book, Sane New World: “During the first few shows I happened to be in The Priory and I didn’t want anyone to know for fear of losing my job.

“My husband would pick me up and all the other inmates looked at me like I was crazy (high praise from the experts) as I was driven home to interview someone with a mental illness without saying a word about how sick I was. Then my husband would drive me back and I’d get back into bed.”

But five years ago she opened up about her problems and toured psychiatric institutions to talk about her illness.

Now, however, she is at pains to point out that her new show isn’t about depression – it’s much funnier than that.

And she insists that Sane New World, which Ruby is performing on Saturday at Birmingham Town Hall, is for everyone.

“It’s nothing to do with mental illness,” she asserts.

“I am one of the one in four who have mentally unravelled, but this is for everyone, because we are all built the same and all share the same frenetic world.

“The show is for anyone who feels their ‘busyness’ is tipping them over. We all have to cope with too much information these days.

“We are simply not equipped for the 21st century. You could say that multi-tasking has driven us mad – like leaving too many windows open on your computer, eventually it will crash.

“I’m not saying there’s anything wrong with that. I love the internet and the ability to go shopping at 2am. But there is a problem when you get addicted to it, like gambling. You have to learn when to shut it down.”

Ruby has found that investigating how the brain works has helped her tame her thoughts. She took a Masters degree at Oxford University in Mindfulness-based cognitive therapy.

“I started to put in my hours as a therapist, but I realised I didn’t have the empathy to qualify, I was starting to lose compassion and I couldn’t fake it,” she says.

“I was always doing it for comedy rather than a career change. Part of my dissertation was my show – I filmed it and they graded me.

“People still come up to me and tell me about their problems, which I don’t mind even though they’re not paying me. I will advise them on the best places to go for help.”

So what makes Ruby happy these days?

“Let’s not say happy,” she says, carefully. “Let’s say content. I get a buzz buying a new pair of shoes, but that very quickly wears off.

“I am content stroking my cat and watching Danish dramas on the TV.”

Ruby is a former actress who joined the Royal Shakespeare Company in Stratford-upon-Avon in 1978. She worked alongside Juliet Stevenson, Zoe Wanamaker and her great friend Alan Rickman.

“He told me I wasn’t a very good actor,” she remembers. “But he encouraged me to turn to comedy. He’s always been my mentor and I run work past him.

“I remember writing comedy and inviting the whole of the RSC, even Trevor Nunn, into my bedroom to do a show.”

* Ruby Wax comes to Birmingham Town Hall on Saturday. For tickets ring 0121 345 0600 or to go www.thsh.co.uk.