A somewhat didactic examination of the biological and psychological bases of normal moods, along with research-based advice on changing bad ones into good ones. Thayer (Psychology/California State Univ., Long Beach) has his own vocabulary for discussing moods. Assuming the interconnectedness of physical and mental states, he says that two arousal continuums--one ranging from energetic to tired and one from calm to tense--together with the thoughts they influence, produce what we call moods. The optimal mood is one of calm-energy; calm-tiredness and tense-energy are less good; tense-tiredness is distinctly bad. The author examines the intricate ways in which these continuums interact with each other; biological influences on mood, such as exercise and food (for instance, he found that sugary snacks increase tension); the congruence between our thoughts and moods (positive thoughts accompany positive moods, etc.); and the effects of such factors as drugs, sunlight, social interactions, and life events. Neurochemistry, physiology, and anatomy are touched on lightly, but Thayer notes that research has far to go in discovering just how these relate to mood. Through self-observation, he says, one can discover one's daily rhythms of energy and predict the likely times of vulnerability to tension. Mood regulation to Thayer is a matter of matching one's activities to one's naturally occurring moods. In focusing on methods people use to alter their moods, he notes that exercise is the most effective way both to raise energy and to reduce tension. Although Thayer seems to be trying to reach a broad audience by putting discussions of methodology and various technical issues in back-of-the-book notes, his classroom style diminishes this work's appeal for the general reader.