High levels of cortisol in the body have been identified as one of the major factors of sleep depravation and loss of concentration, says a top nutritionist. Dr Shawn Talbott, an expert in nutrition and biochemistry at the University of Utah in the United States, says people in high-pressure jobs or living in a fast-paced city are loosing their sharpness because of over production of ther stress hormone cortisol. 'Similar trends are happening in other fast-paced cities in the world, including Hong Kong, because of intense stress and getting less than eight hours of sleep a day,' Talbott said at a seminar in Hong Kong recently. He says work pressure or financial pressure create high levels of cortisol that cause constant fatigue and bad sleeping patterns. Eventually depression sets in as the high concentration of cortisol blocks the signals sent by Serotonin, the 'feel good' hormone. According to a recent survey of 1,239 people aged 15 to 45 in Hong Kong, Taiwan and Shanghai, with about 400 respondents in each place, Hong Kong citizens have the worst sleep quality because of work-related stress. Sixty-two per cent of respondents in Hong Kong complained of insufficient sleep, and more than a half suffered from insomnia. Prolonged high levels of cortisol eventually leads to the breakdown of the body's tissues and cells, Talbot said. 'First, it's the immune system, so you start catching every cold that goes around, and you get ill a lot. Then, it is the brain cells. You find it harder to remember names, addresses and stuff, and you can't concentrate. While immune system cells can be recovered within a short period of time, it takes two to three times longer for brain cells to recover provided the person is no longer exposed to stress. 'There is no way that you can stay away from stress, but you can always control the way your body is reacting through regular exercise, diet and stress management.'