If you are a rat being chased by a cat, you should not stop to sleep or eat, even if you have missed a meal and it is past your bedtime. Internal programs for sexual behavior and metabolic programs for growth and reproduction are turned off. The amygdala, as we have seen, encodes the memories of fear. The hypothalamus controls many of the vegetative functions and the secretion of stress hormones, and sexual behavior. Now let us consider how stress relates to depression.
Depression is a particularly cruel disorder.
It darkens memory, diminishes hope, and precludes the taking of pleasure in everyday events or in the contemplation of what one has achieved or become, depriving those afflicted of the most gratifying aspects of their past and present. Depression also intrudes upon fundamental biological processes that regulate sleep, appetite, metabolic activity, autonomic function, neuroendocrine regulation, and growth and reproduction. Not all depression reflects a suppression of thought and feeling. One of the most severe forms of depression actually is a state of pathological hyperarousal, but an exceedingly melancholic and anxious arousal. The anxiety is most often directed against the self and expressed as feelings of worthlessness and guilt.