The term lunatic was derived from the Latin word luna meaning moon. Many studies have tried to establish a correlation between behavior and the lunar cycle but have not been successful. Dr. Ivan Kelly, a psychologist at University of Saskatchewan has written 15 papers and examined 50 others on the topic and concludes that there is no correlation of a lunar effect. A psychiatrist--Arnold Lieber in 1978 published a book that explained that the moon's gravitational pull would have an effect on humans the way the moon's pull affects the tides. However, although people's bodies are mostly water, the distant moon could not make an impact on small humans. There has long been a belief that the full moon affects behavior in humans and other animals, but the research has not established this.