The predominant feature of depressive disorders is the presence of sad, empty, or irritable mood, accompanied by physical and cognitive changes that significantly impair a person’s ability to function. Differences between the depressive disorders depend largely on duration, timing, or origin.
Depressive disorders are distinct from feeling unhappy or sad (which is commonly referred to as ‘depression’) in that they involve more severe and persistent symptoms. Depressive disorders are often long-lasting, recurring illnesses. People with depressive disorders feel depressed, sad, hopeless, discouraged, or ‘down in the dumps’ almost all the time. They also experience other symptoms including sleep disturbances (including difficulty getting to sleep, frequent waking during the night, being unable to wake in the morning, or sleeping too much); loss of interest in daily activities; a lack of energy, tiredness and fatigue; restlessness, irritability, or anger; difficulty concentrating, remembering, and making decisions; feelings of guilt or worthlessness; appetite changes (either decreased or increased appetite); loss of sex drive; and thoughts of death or suicide.