Almost everyone has been touched by at least a mild form of depression, and thus has some sense of what severe depressive illness must be like. It provides a compelling treatment of questions about the nature of depression, where it comes from, who's at risk, and what it indicates about human experience. Depression is a highly prevalent health problem, affecting about 11 million Americans every year. Its costs are staggering - $43.7 billion annually in lost productivity, lost income, and increased health care costs. These numbers put depression on a par with heart disease as one of the most expensive diseases in the United States today. But, unlike heart disease, depression is widely misunderstood. About two-thirds of the cases of depression go undiagnosed and untreated. With a compelling mix of information, illustration, and interpretation, David B. Cohen explores the current state of knowledge about depression, including the powerful influence of genetics. In addition to depressive illness, the book deals with related ideas and topics such as mourning, mania, the rhythms of sleep, self concepts, and suicide. Insights from psychology and psychiatry are blended with history, literature, current events, and personal observation, and topped off with a dose of common sense.