An illness that involves the body, mood, and thoughts and that affects the way a person eats, sleeps, feels about himself or herself, and thinks about things. Depression is not the same as a passing blue mood.
Increased aches and pains, which occur in about two out of three people with depression. Chronic fatigue. Decreased interest in sex. Decreased appetite.
Rather, there are many possible causes of depression, including faulty mood regulation by the brain, genetic vulnerability, stressful life events, medications, and medical problems. It's believed that several of these forces interact to bring on depression.
Lack of sleep can cause some of the same symptoms as depression -- extreme tiredness, loss of energy, and difficulty concentrating or making decisions. In addition, untreated depression may result in weight gain or loss, feelings of hopelessness and helplessness, and irritability.