For more than forty years, William Dement has been researching the subject of sleep and of sleep-related problems. According to Dement, if we dont sleep well, we cannot be healthy; but its impossible to sleep well if we dont know what disturbs our sleep patterns, or what we stand to gain from an adequate nights rest. We are careful about our diets and we make sure we get enough exercise. Yet we often forget that it is equally important to sleep well. Sleep is often sacrificed to the demands of our daily lives. Doctors still tend to minimise the physical, emotional and psychological risks that result from a failure to give sleep its due. This fundamental work by a world-renowned specialist enables us to find out how we should sleep, in order to feel better and keep healthy. William C. Dement is a world authority in the field of sleep and in the treatment of sleep disturbances. In the 1970s, he founded one of the earliest centres specialising in the study of sleep at Stanford University, in California. He continues to teach at Stanford. Christopher Vaughan is the author of How Life Begins : The Science of Life in the Womb.