I've always been an oversensitive perfectionist. My family used to call me "Miss 35" because, at 11, I acted so much older than my years. But I thought of myself as a strong, pragmatic person who didn't have any problems dealing with stress.

Perhaps that's why when I did develop an anxiety disorder I found it so hard to accept that I'd lost control.

It was just over a year ago that things started to unravel. In addition to my regular work on GMTV, I'd taken on a theatre job, a role in a pantomime in Brighton. I found myself working 16-hour days, seven days a week, and also commuting between London and Brighton.

Knowing how lucky I was to have both jobs, I felt that I had to put 100 per cent into them.

I coped fine for the first few weeks, but then I started to feel unable to apply myself to anything properly. I hardly saw my partner and I felt guilty because I couldn't give any time to my friends or family. So, instead of sleeping, any spare time I had was spent catching up with friends, people-pleasing to the detriment of my own mental health. I didn't enjoy socialising and I'd wake up feeling as if I'd been run over by a bus. I'd lie in bed with lines and songs and camera directions going round and round in my head.

I'd lie in bed worrying about irrational things Nobody at work could tell that I wasn't coping. Somehow, I'd get through the day. But, at home, in the evenings, I'd find myself bursting into tears for no reason at all. I couldn't understand why, when I was doing what I'd always wanted to do, I was feeling so awful, so isolated. My mother was concerned and told me to rest. Instead of taking heed, I tried to protect her. I told her I was fine; I would even go round to my parents' house and do the washing-up, to "prove" how well I was coping.

I made it through the panto run and at the end of January I went on holiday to Thailand with my boyfriend. Usually, I love travelling, but this time I felt dreadfully homesick. I found it difficult to get to sleep and I'd lie there worrying about the most irrational things. What if we get hit by a tsunami? What if a spider comes into the room? Or a snake? What if something happens to my family? I was relieved when dawn came and I could get up, so I'd no longer be alone with my thoughts. For the first time, I didn't come back refreshed from my holiday.

Things got easier for a few months, but of course I hadn't really dealt with anything. And by the summer I felt myself losing control again. My relationship was starting to break down and I was also anxious about family problems: cancer was diagnosed in my elder brother's girlfriend and my younger brother was suffering from panic attacks (there's some evidence that anxiety disorders can run in families).

I started to obsess about work, learning lines several days early instead of relaxing. I worried about my friends; I'd think, "I haven't called that person for ages, they must think I'm a rubbish friend". I worried about my parents, who were upset about my brothers, and, of course, I worried about my brothers, too.

Most people have at least one panic attack

All that anxiety built up inside me. I suppose it was inevitable that it had to come out somehow. And at the end of September 2006, come out it did, in the form of panic attacks. The first one happened at a friend's house, in the middle of the night. For anyone who hasn't had a panic attack - and most people will experience at least one in their lifetime - they are extremely frightening. The sensation starts in your chest. It's like someone's prodding a hot poker into your breastbone. Then your chest feels tight and fluttery, you start to hyperventilate, your heart begins to palpitate and you can feel your pulse thudding in your ears.

Suddenly you feel ultra alert, your eyes are very wide, and a hot, then cold, wave spreads across your body. You can't breathe. You really believe you're going to die.