This document discusses various topics related to psychopathology. It begins by defining mood disorders as affective disorders involving prolonged disturbances of mood and emotions. It then discusses phobic disorders, categorizing them as agoraphobia, social phobia, and specific phobia. Several case studies are presented examining specific phobias and obsessions. The document also discusses characteristics of PTSD, similarities between mood disorders and anxiety, two types of depression, biological rhythms including circadian, infradian, and ultradian rhythms, research on circadian and infradian rhythms, and the roles of endogenous pacemakers and exogenous zeitgebers.