In a physiological level, anxiety symptoms include rapid heartbeat, muscle tension, queasiness, dry mouth, or sweating. Sometimes a person confuses panic disorder with a heart attack because the symptoms can be similar. Depression is a state of sadness, hopelessness, lethargy, worthlessness, irritability, and loss of vitality. A person who feels depressed also may experience biological changes, such as a lack of appetite, loss of libido, and sleep disruption. To be considered a disorder depression must last over two weeks.
Bipolar disorder is probably the best known mood disorder.
This disorder is biologically based, although mood disorders may also result from substance abuse or illness. Compulsions are the behaviors or rituals that are used to ward off the anxiety brought about by the obsession. Obsessive-compulsive individuals may engage in many hours of checking, cleaning, and ordering. These behaviors are out of a person's control and can severely disrupt everyday life. Symptoms include recurring thoughts and images relating to the event, nightmares, flashbacks, panic attacks, depressive feelings and loss of pleasure.