Marian Keyes, one of Ireland's most successful novelists, has revealed that she is in the grips of a "crippling depression."

Keyes, whose hit novels have included "Rachel's Holiday," "Lucy Sullivan is Getting Married," "Watermelon" and "Sushi," says she feels as if she is living in hell.

"I still feel like I’m living in hell. I can’t eat, I can’t sleep, I can’t write, I can’t read, I can’t talk to people," she says.

"The worst thing is that I feel it will never end. I know lots of people don’t believe it, but depression is an illness, but unlike say, a broken leg, you don’t know when it’ll get better.

Keyes has often spoken about her former alcoholism and her life-long battle with depression but says, "this is much much worse."

She revealed her illness in her new year's newsletter to fans.

"My dear amigos, happy new year to you all and I hope your festive season was not too unpleasant. I’m very sorry but this is going to be a very short piece because I am laid low with crippling depression. Regular readers know that I’ve been prone to depression on and off over the years but this is in a totally different league.

"This is much much worse. I know I’m leaving myself open to stinky journalists saying ‘What has she got to be depressed about, the self-indulgent whiner, when there are people out there with real troubles?’ so I won’t go on about it.

"All I will say is that I’m aware that these are terrible times and that there are people out there who have been so ruined by the current economic climate that they’ve lost the roof over their heads and every day is a battle for basic survival and I wish I could make their pain go away. But although I’m blessed enough to have a roof over my head, I still feel like I’m living in hell."

Marian Keyes: Gripped by crippling depression