depression

Depression is a mental state of low mood and aversion to activity. It affects about 3.5% of the global population, or about 280 million people worldwide, as of 2020. Depression affects a person's thoughts, behavior, feelings, and sense of well-being. The pleasure or joy that a person gets from certain experiences is reduced, and the afflicted person often experiences a loss of motivation or interest in those activities. People with depression may experience sadness, feelings of dejection or lack of hope, difficulty in thinking and concentration, hypersomnia or insomnia, overeating or anorexia, or suicidal thoughts.

Depression can have multiple, sometimes overlapping, origins. Depression can be a normal temporary reaction to life events, such as the loss of a loved one. Additionally, depression can be a symptom of some mood disorders, such as major depressive disorder, bipolar disorder, and dysthymia. Depression is also a symptom of some physical diseases and a side effect of some drugs and medical treatments.