It is the news that all sloths have been waiting for. Scientists in Germany have found that too much exercise is bad for you and that doing less could lengthen your life. In a new book called The Joy of Laziness: How to Slow Down and Live Longer, Dr. Peter Axt, retired professor of health science at Fulda University near Frankfurt, and his daughter, Dr. Michaela Axt-Gadermann, a GP, say that everybody has a limited amount of 'life energy' and that the speed with which it is consumed determines their life span. They argue that high-energy activities, such as pounding the treadmill at the gym, accelerates the aging process and makes the body more susceptible to illness. 'A more relaxed way of life is important for your health,'said Dr. Axt-Gadermann. 'If you lead a stressful life and exercise excessively, your body produces hormones which lead to high blood pressure and can damage your heart and arteries.' Dr. Axt-Gadermann said that one key difference between the lazy and those who exercise was that the more active body produces. more 'free radicals'--unstable oxygen molecules that are believed to speed the aging process. She added: 'Laziness is also important for a healthy immune system because special immune-cells are stronger in times of relaxation than stress. During relaxation or' down time', your metabolism is less active, which means the body produces fewer free radicals.' 'If you do a lot of sport or are permanently stressed, then your body will produce more free radicals and that is one reason why your life could be shortened.' Dr. Axt-Gadermann and her father also say that laughing is healthier than running. 'When you laugh, your body produces the hormone serotonin which makes you feel happy and relaxed, ' said Dr. Axt-Gadermann. 'The heartbeat races and blood pressure is raised for a short while, without activating your metabolism and producing the free radicals which spend your life energy. Basically, laughing is a good training session without the negative side-effects.' To illustrate the theory that laziness equals longevity, The Joy of Laziness also suggests that early risers are more prone to stress and that late sleepers live longer because they conserve their energy. 'People who would rather laze in a hammock instead of running a marathon, or who take a nap instead of playing squash, have a better chance of living into old age.' The Joy of Laziness, which is published soon, will be essential reading for Dan Kieran, the 29-year-old deputy editor of The Idler, a literary magazine. 'This book definitely makes sense to me, ' said Mr. Kieran. 'I spend one day a week in the office and the rest of my time involved in a tot of relaxation. Having the right amount of laziness in your life is a vital component to being happy. We live in a culture of guilt, where laziness is scorned. However, I firmly believe that we do not need to do half as much exercise as people think and it is very important to just lie clown and do nothing sometimes, ' he said. The medical establishment, however, is skeptical. Dr. Vivienne Nathanson, the head of science and ethics at the British Medical Association, said that moderate exercise should not be set aside in favour of lazing around. 'It is a very tempting theory as so often, many of us feel that we cannot be bothered with exercise, ' she said. 'However, I would not agree that people have a set amount of expendable energy during a lifetime and that exercise is bad for you. In fact, done sensibly, exercise lowers the blood pressure, improves your metabolic state and can improve health and contribute to a longer life. 'Dr. Graham Archard, the vice chairman of the Royal College of General Practitioners, said: 'I can understand why the book might sell well as it is always nice to be told that you can sit on your backside and do nothing.' The word 'sloths' in the first paragraph probably means