Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest. You may have trouble doing normal day-to-day activities, and depression may make you feel as if life isn’t worth living. People with depressed mood can feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, ashamed or restless. They may lose interest in activities that were once pleasurable, experience loss of appetite or overeating, have problems concentrating, remembering details or making decisions, and may contemplate, attempt or commit suicide. Insomnia, excessive sleeping, fatigue, aches, pains, digestive problems or reduced energy may also be present.