Sarah Jessica Parker: `I get so nervous that I can`t eat`

The Sex And The City star describes herself as a worrier who lies awake at night going over 'the internal lists, the children's doctor's appointments, the letters to write, the school projects'.

But when it comes to her work, like on the set of her new movie I Don't Know How She Does It, her nerves take on a whole new form.

'I lose my appetite,' she told Vogue. 'By Wednesday of the first week on I Don't Know How She Does It, I was sobbing. I was apologising. I was feeling so awful and ashamed, like I had let the director down... I'm like that two weeks into every movie. But the beauty of nerves is that you can always find a comrade in it.'

But on this occasion she managed to find comfort in the fact that her co-star Pierce Brosnan was suffering too. '(He) was a nervous wreck! Of course, by then I was really relaxed, but I was so comforted by it,' she said.

The 46-year-old is raising son James Wilkie, eight, and two-year-old twins Tabitha and Loretta with husband Matthew Broderick, 49.