Ruby Wax is feeling one of her lows coming on. She is in a breast clinic in London for her annual scan and recognises the depressive symptoms, a gradual creeping numbness that leaves her feeling like "an empty thing".
But she says she will be in good form for her show in Belfast's Waterfront on Wednesday and and Thursday, and promises that it will be funny.
"Once you have this disease and you've had three episodes or more, you can't prevent it reoccurring but you can learn to cope," she says in that distinctive nasally New York twang, blurred only a little by her four decades in London.
"The chances are that it will come back and you can't just make it disappear, but you can re-train your brain to lessen it. In my case that involves lowering the bedroom blinds and resting, to get the cortisone levels down, instead of rushing about and accepting dinner invitations and pretending everything's okay."
The petite apple-cheeked comedienne and writer, famous for her brash celebrity interviews and collaborations with her friends Dawn French and Jennifer Saunders, has won high praise for her fascinating, moving and naturally funny book Sane New World, an exploration of the chemical make-up of the brain and how it can be changed for the better, using techniques such as mindfulness and cognitive behavioural therapy (CBT) to break old ingrained mental habits.
"I'm not bi-polar but in the past I would have speeded up when I felt this coming on, as I do right now," she explains, on her mobile phone from the clinic's waiting room. "I would have been rushing around trying to find the perfect pair of shoes or set of cushions in a particular shade of blue. Now I know to shut the doors and batten down the hatches. I even went to a retreat once, it cost £29 a week, so I'd have no stimulation at all. It's absolutely crucial to completely slow down. Medication has helped but it hasn't cured me."
From personal family experience I know Ruby's coping mechanisms can work. (My sister's post-operative, trauma induced ME condition has improved greatly though a mindfulness technique called the Lightning Process.) Ruby graduated from Oxford last Monday with a Master's in mindfulness-based cognitive therapy (MBCT), having taken a postgraduate diploma in psychotherapy and counselling.
"Yes it was hard and I had to study a lot but it was worth it," she says cheerfully, despite the encroaching gloom. "I put what I've learned into practice every day. The meditation I do – usually every morning when I wake up; sometimes in taxis – is stolen from Buddhism. I'm not a Buddhist; I have no faith. I wish I did. As I say in my book, I'm haunted continuously by thoughts of my imminent death.
"Anyway, I focus on one particular sense, such as what I can hear on the next room or my bum on the chair, to bring down the cortisone levels. It's about tricking your body. Mindfulness can change the whole molecular structure of the brain so you can deal with extreme pain and stress."
Whether it's because of the fear of death or not, Ruby never gives away her age. Going back on her career, she would appear to be 60 this year but still has that firm round face and well-padded cheekbones which make her look younger.
It's a coincidence to be talking to her, as I just spotted her young self in a blink-and-miss her role in a DVD of the film Chariots of Fire the other night. She joined the Royal Shakespeare Company when she first came to London in her early 20s and admits she always wanted to be an actress.
"All girls do. Then the realisation eventually dawns that you're not a good one. I had a bigger part in that movie originally but I was cut from it."
Throughout her acting and highly successful television career she suffered from low mood spells but never realised what was wrong. It was only when she looked back on her childhood, as an adult, that she realised her depression was triggered by her "very sick" mother Berta, an Austrian Jew, like Ruby's father, who had fled to America to escape the Holocaust.
"My mother was an angry depressed person with a very bad temper," she says. "Growing up I would spend days in bed to escape her screaming. That was depression but nobody had a name for it.
"It was a very dark time but I have forgiven her. Depression is not all rooted in parenting – it's very hard to say if it's nature or nurture. I just don't know but if you have the gene and had abuse, that gene gets switched on.
"I became this little show-off who hoped people would like me – I don't know whether it was because of my mother, but sometimes you feel you have a lot to prove because of having gone through humiliation as a child. It's ironically the very ones who will have the worst stage-fright who will go into show business, the opposite of what you'd expect, because of having something to prove."
Ruby was diagnosed with clinical depression after finding herself unable to get out of bed when she was pregnant with her third and youngest child Marina, now a 19-year-old aspiring actress, from her happy 24-year marriage to Ed Bye, whom she met when he directed her series Girls On Top. She had mistakenly assumed the "dead, stoned numbness" she felt was glandular fever.
Fearing the stigma would put her out of work, she didn't let on, but things came to a head when she was interviewing someone with depression, for a mental health series on the BBC website.
"The depressive saw right through me. I was speaking robotically, just dead. After the show I was carted off to the Priory and became an in-patient. After that when the inevitable crashes came I'd end up in hospital, just numb.
"Mental illness is torture. You want it to stop and you think if I was in an accident right now, it wouldn't be so bad. I had so much therapy that I grew sick of my own story but it got me researching mental health and that led me to discover mindfulness.
"In a nutshell, you have to spend time paying attention to your thoughts, feelings and sensations. Once you train your attention, you can regulate your focus and you won't stay up all night listening to the voices in your head."
Depressives are often noted for their searing honesty, perhaps partly as result of refusing to look at life though rose-tinted spectacles.
I tell Ruby that along with Joan Rivers, she's my favourite funny lady, and quote her Joan's definition of good comedy, which she came out with in a recent Q&A: "Outrageous honesty, first and foremost."
"Yes, that's exactly right," agrees Ruby, at this stage filling in a form for the clinic's receptionist. "Joan speaks so honestly – I wish I'd said that. She started off the whole thing for us female comic writers but she's of another generation, a little more jokey and schticky. We're not just about telling jokes but I do admire her."
The acerbic Rivers has credited the late Phyllis Diller for getting the ball rolling for her and the fact that Diller's comedy is associated with her mistakenly Jewish background (she was a Methodist of German/Irish ancestry) – as is Joan's and Ruby's, is hard to ignore, despite the fact Ruby hates labels. It's something a subject she touches on in her current show.
"The underlying theme of whole thing is this crazy competitiveness we're slaves to nowadays. We pride ourselves on being oh so busy and we're killing ourselves. "It's like: 'How are you?'
'Well I've had two heart attacks.'
'Oh that's great! Well done!'"
"I also do envy in the show – it's basically me tearing out pages of all these celebrities from Hello magazine and going 'Die! Die! Die!'. I look at fame like an illness – the famous get swollen with narcissism. They make fair-weather friends, especially taxi drivers.
"So many people now are making money and becoming famous with no skill at all, 600 million years after we crawled out of the sea – how far have we come? It seems to be different in Ireland – I like Ireland the most. The Irish are ironic and smart."
With no more television planned, Ruby is writing another book on how the brain works. She is missed on screen by fans like me, who will never forget her trying to fix up a cringing Joan Collins with a younger man in the exotic location they were filming in, or getting Pamela Anderson to discuss her private parts in a discussion about sexual positions, or wearing a pair of crotchless pants on her head while interviewing Madonna, or clapping along to Imelda Marcos's excruciating singing voice in her Manila apartment.
"Imelda Marcos was my favourite because she was the craziest and the most deluded. It was the wildest ride. She craved fame," says Ruby.
She is interrupted by the receptionist calling her for her scan.
"Oh I have to go and get my breasts photographed now," she laughs huskily. "Are you coming to the show? It's not about depression by the way – it's funny and it's about what's wrong with all of us, not just the one in four who affected by depression.
"We're just winging it – every one of us."
Career in the spotlight
* Born Ruby Wachs in 1951 to Jewish parents in Illinois in the USA
* Came to the UK in the Seventies and began her career as a straight actress with numerous stage roles, including joining the Royal Shakespeare Company, where she starred alongside the likes of Juliet Stevenson and Michael Hordern, among others
* Her comedy career took hold during the UK Alternative Comedy scene of the Eighties, where her brash and loud interviewing technique endeared her to British audiences
* Among the famous faces she has interviewed are Boris Yeltsin, Imelda Marcos and Pamela Anderson
* In 1989, she enjoyed a cameo in hit BBC sitcom Red Dwarf as a showbiz reporter, as well as guest appearances in the Nineties in Absolutely Fabulous
* She has also branched out into teaching business communication in the public and private sectors