Depression is a mental illness that affects a person's family, work or school life, sleeping and eating habits, and general health. Depressed people may be preoccupied with, or ruminate over, thoughts and feelings of worthlessness, inappropriate guilt or regret, helplessness, hopelessness, and self hatred. They may also blame themselves for negative events.

Other symptoms include poor concentration and memory, withdrawal from social situations and activities, reduced sex drive and thoughts of death or suicide.  The person may report multiple physical symptoms such as fatigue, headaches, or digestive problems.