Preventing occupational disease and injury, second edition. Levy BS, Wagner GR, Rest KM, Weeks JL, eds. Washington, DC: American Public Health Association, 2005 Jan; :184-187
Depressive episodes are serious medical conditions that affect thoughts, feelings and the ability to function in everyday life. In typical mild, moderate, or severe depressive episodes, an individual suffers from a lowering of mood, reduction of energy, and decreases in activity level. Capacity for enjoyment, interest, and concentration is reduced, and marked fatigue, after even minimal effort, is common. Sleep is frequently disturbed and appetite diminished. Self-esteem and self-confidence are almost always reduced and feelings of guilt or worthlessness are often present. The lowered mood is generally unresponsive to circumstances and varies little from day to day. Episodes may be accompanied by various somatic symptoms including psychomotor retardation, agitation, loss of appetite, weight loss, and loss of libido. Depending on the number, variety, and severity of the symptoms, depressive episodes can be labeled as mild, moderate, or severe.