Just a few years ago, bestselling female fiction writer Marian Keyes was in the depths of despair, suicidal and unable to function properly.

The top Irish writer - whose novels, including Lucy Sullivan Is Getting Married, This Charming Man and The Brightest Star In The Sky, have been translated into 36 languages and sold more than 33 million copies worldwide - had been under a cloud of clinical depression for more than four years.

In 2010, she announced in a newsletter to fans that she was suffering so severely that she couldn't sleep, read, write, or talk.

"Everything stopped. It was really unexpected. I've always been respectful of the fact that I'm prone to depression. I've tried to take care of myself and I thought I was, but it's an illness like any other and I found it hard to accept that.

"I thought it was my fault and that I'd done something wrong; that I'd brought it on myself somehow. But once I started thinking of it as an illness in the way that cancer is an illness or emphysema is an illness, and that things happen seemingly without a reason or cause, that was the way I had to think about it."

She later revealed that despite trying every treatment on the market - from acupuncture and vitamin B12 injections to yoga, cognitive behavioural therapy and meditation - suicidal thoughts led her to buy a Stanley knife, although she stopped short of using it.

She fears the depression, which lasted four-and-a-half years before finally lifting in 2014 as inexplicably as it arrived, may return. After endless therapies, both conventional and alternative, she's no longer asking why it happened or how it could be cured.

She tries to avoid talking about that period, however, which she admits is a change from her old belief, that talking always helps.

"Sometimes just burying something is a better way to go forward. It's not something I dwell on. All the way through, I was trying different things to try and find out how I could get better, but nothing helped.

"At this stage I feel there isn't really any point in going back and wondering, 'Was there a trigger?' If there was, I would have found it during my exploratory series of adventures. Sometimes it's better to parcel something up and put it in a box in your head and hope that you never have to open it again."

But she's cut down on her heavy workload, and her husband and full-time PA Tony Baines makes sure she's not taking on too much.

The 52-year-old Dubliner doesn't do many interviews, because talking about the depression can start to mess with her mind, she explains.

"People still want to talk about it and I'm not able," she reflects. "When I have tried to talk about it my own backlash has been unpleasant. I've ended up feeling like I'm going back into it, and that's so frightening.

"I hate saying no and I hate disappointing people, but Tony will say no. He's the voice of reason. But it goes against the grain because I'm a people pleaser.

"I was such a hard-worker, I really grafted, and I did so much travel to promote my books, but I can't do that now."

She makes references to some of the dark times in her latest collection of writings, Making It Up As I Go Along, a compilation of essays both published and previously unpublished, covering a myriad of topics, from cosmetics and beauty treatments to holidays, family events, guilty pleasures and turning 50, all in her trademark humorous style.

She recalls visiting her local chemist to pick up her 'Madness-Be-Gone' kit, tweeting 'Is anyone awake?' during one of her frequent bouts of insomnia, makes gentle fun of the various therapies she has tried with little success, along with passing references to the discovery that she and her husband couldn't have children.

Keyes has long been aware she has an addictive personality - she's a recovering alcoholic who hasn't had a drink for 22 years - and mentions in her latest essays the years lost in an alcoholic haze between the ages of 20 and 30.

While Keyes was at her darkest point, her husband discovered climbing - which helped him cope. It's another thing she mentions irreverently in her latest book.

"He found comfort and purpose and pleasure in doing that," she explains. "He's climbed Mount Elbrus, the highest mountain in Russia, and he's climbed Mont Blanc and has more ambitions and more plans. It was his release."

And she admits that writing helped her - Keys wrote The Woman Who Stole My Life and The Mystery Of Mercy Close during the four-and-a-half years she was under the grip of depression. She also learned to bake, which proved one of the best therapies and resulted in another book, Saved By Cake.

"Baking makes me focus. On weighing the sugar. On sieving the flour. I find it calming and rewarding because, in fairness, it is sort of magic - you start off with all this disparate stuff, such as butter and eggs, and what you end up with is so totally different. And also delicious," she said at the time.

Today, after much soul-searching, Keyes has stopped looking for answers and seems to be coping.

Last year she was burgled; thieves ransacked the house.

"The place was wrecked. There was broken glass everywhere and my jewellery was taken and everything had been gone through. There isn't a person alive that hasn't been burgled but it was a shock. I felt angry at the time but it passes quickly.

"At first I was afraid of leaving the house and making it vulnerable. For weeks afterwards, I felt very uncomfortable if both Tony and myself were going to be out. But at the end of the day, it's only stuff. Nobody was hurt."

She's started another novel, Time Off For Bad Behaviour, due out next year, about a woman whose husband of 16 years tells her he still loves her but wants a six-month break from being married.

Years ago, Keyes hoped for a state of eternal happiness, but realises now that doesn't exist.

"I was completely naive. Nobody's happy all the time," she reasons. "Happiness is just one of hundreds of states of mind that any human being goes through, and when it comes along it's really nice to jump on it.

"Then when it moves off, I can realise I'm not doing anything wrong."

:: Making It Up As I Go Along by Marian Keyes is published by Michael Joseph, priced £14.99. Available now