Major depressive disorder, also known as clinical depression or simply depression, is a mental health condition characterized by persistently depressed mood, loss of interest in activities that were once enjoyable, and a range of other physical and cognitive symptoms. These can include changes in sleep patterns, fatigue, difficulty concentrating, feelings of worthlessness or guilt, and thoughts of death or suicide.
The exact causes of depression are not fully understood, but a number of factors are believed to play a role, including genetics, brain chemistry, and life events. Depression can be treated using a range of approaches, including medication, therapy, and lifestyle changes.