Cognitive therapy is a kind of psychotherapy used to treat depression and other mental disorders. Cognitive therapy is one of the treatments used (usually in conjunction with mood stabilizing medications) to treat bipolar disorder. Its practitioners hold that the cause of many (though not all) depressions are irrational thoughts; with thoughts stipulated as the cause of emotions rather than vice-versa, cognitive therapists reverse the causal order more generally accepted by psychotherapists. The therapy is essentially, therefore, to identify those irrational thoughts that are making one unhappy and what it is about them that is irrational; this is done in an effort to reject the depressing thoughts and replace them with more accurate, but also more cheering thoughts. This is a more sophisticated development of the method--annoying to cynics and pessimists everywhere--demonstrated by Hayley Mills in the movie Pollyanna and James Stewart in the movie Harvey and millions of optimists who enjoin us to "think happy thoughts."
Thereafter cognitive therapy was popularized by the self-help book Feeling Good: The New Mood Therapy (Revised edition; New York, 1999: Avon Books) [ISBN 0380810336] by David D. Burns. Burns reports (in his introduction) that, according to a 1994 study, this book is the most-recommended by U.S. psychotherapists. Burns also reports about a study in which two groups of moderately depressed patients were given Feeling Good to read at different times (one served as a control group for the other); after three months, 75% of the first group and 73% of the second no longer qualified as depressed, and after three years, 72% still were not depressed.