Ralph Fiennes suffers from panic attacks.

'The Constant Gardener' actor often wakes up in a sweat in the middle of the night with a feeling of impending doom hanging over him and lies awake worrying about his life.

He said: ''I have huge anxiety attacks. I'll wake up early in the morning with my brain anxious about something and I don't even know what it is, just a general sense of profound uncertainty. It's from the unconscious, I suppose, fears about existence. A weird twilight zone.

''We feel we can organise our lives and have an order that we can control but really we can't, it's always paper-thin and underneath there's this lurking chaos. You think, 'F**k! This could come at me at any moment!' ''

The 50-year-old star admits his anxiety also translates into being socially awkward when he meets new people and not being able to concentrate on what they're saying.

Ralph told Britain's Esquire magazine ''I get accused of zoning out of conversations and gazing into the middle distance, which I do when I'm somehow not at ease. I often feel a bit lost in social situations and that's when I can button up.

''I have moments - not ever y day - when I feel myself retreating. Later on I'll think, 'That person meant well. I didn't need to be like that'.''

The British star's biggest regret is his mother passing away before he became a household name thanks to the success of 'Schindler's List'.

He recalled: ''Just as 'Schindler's List' was coming out and I was on the receiving end of a whole lot of attention, my mother died of cancer. I would have loved her to have seen some of the stuff I've been part of. I know all my brothers and sisters feel the same. We often talk about it.

''My father was around for a bit but it will always be, for all of us as a family, a huge sadness that both our parents died when they did. There are moments when it surprises you; you think you're on top of it and the grief will suddenly come back.''