Bestselling author Marian Keyes has given a searingly honest account of her battle with depression, revealing that at one stage she contemplated suicide up to 40 times a day.

The Irish novelist, who has sold 35 million copies of her books around the world, told Desert Island Discs how eight years ago, during one of her worst periods of depression, she experienced constant urges to harm herself.

Watch: Marian Keyes tells Stylist of the authors who inspire her

"Suicidal impulses started and it was very hard to physically to stop myself from going through with it, for months and months every day was an enormous effort not to do the acts of wounding myself. That went on for 18 months,” she tells the programme’s presenter, Kirsty Young.

She was eventually hospitalised after she became unable to eat, sleep, or interact with others.

It was during this stage that the 53-year-old wrote her novel The Mercy of Mystery Close, in which the protagonist planned to kill herself in a hotel room – a scene Keyes has previously told The Guardian was inspired by her own experience.

“I had two goes going out assembling the whole kit and buying paper and Sellotape to write the note,” she says. “The conversation Helen has with the man in the shop, I actually had that, with him asking: ‘What is it you’re proposing to cut?’

“I was absolutely going through who would find me, leaving money for her to apologise … I wasn’t in my right mind.”

"It's an illness and it ran its course,” she tells Young. “Three years ago, at the start of 2014, it was like coming up from the bottom of the ocean. It was really speedy. I had always described myself as melancholy or depressive but I hadn't a clue, anything I had before was a blue day by comparison, this was altered perceptions, a mental illness."

Keyes says that when she moved to London in her twenties she became dependent on alcohol, describing it as the love of her life.

She described writing as her "rope across the abyss" and submitted her first short story just months before entering rehab. Her debut novel Watermelon was published in 1995.

"It was that primal urge in all of us to stay alive, saying 'I can give you this will you live for this? It didn't get me sober but gave me something to hope for."

Keyes, who has now been sober for 23 years, explained on the programme why she’ll never give any of her novels a downbeat ending: “I need to feel hopeful about the human condition. And it isn't entirely ludicrous to suggest that sometimes things might work out for the best.”

• If you’re struggling with intrusive thoughts of suicide and self-harm, or feelings of depression, Samaritans are open 24 hours a day, 365 days a year on 116 123, or you can email jo@samaritans.org
• If you’re worried about your own or someone else’s drinking, the national alcohol helpline Drinkline is available on 0300 123 1110 (weekdays 9am – 8pm, weekends 11am – 4pm)

Images: Rex Features