This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book addresses the effects of caffeine on health and behavior provide considerable information relevant to arousal theory. It shows that the overall relationship between consumption and coronary heart disease is J-shaped or U-shaped, such that low consumption may reduce and high consumption increase the probability of developing heart disease. The book also shows that caffeine appears to increase levels of reproductive hormones during the follicular phase. It also addresses the impact of caffeine on behavior and related psychological functioning. The book considers the role of caffeine in psychopathology and concludes that excessive consumption of the drug can cause or contribute to anxiety, depression, delirium, mania, and even psychosis. It provides details on the effects of green and black teas on health.