In plain words
Depression is a common mental disorder. It is different from ordinary mood changes: a low mood or loss of interest or pleasure lasting most of the day, nearly every day, for at least two weeks.
There is effective treatment for mild, moderate and severe depression. If you are thinking about suicide or harming yourself, contact local emergency services or a local crisis line now.
Key facts
- WHO estimated that in 2023 about 4% of the population, including 5.2% of adults, had depression: roughly 322 million people.
- It is about 1.5 times more common in women than in men.
- In high-income countries only about one third of people with depression receive mental health treatment. WHO names lack of investment, too few trained providers and stigma as barriers.
Symptoms
Depressed, irritable or empty mood, loss of interest, poor concentration, excessive guilt or low self-worth, hopelessness, thoughts of dying or suicide, disrupted sleep, changes in appetite or weight, and feeling very tired. Episodes are graded mild, moderate or severe by the number and severity of symptoms and the effect on functioning.
Patterns
A single episode, recurrent depressive disorder (at least two episodes), or bipolar disorder, where depressive episodes alternate with manic symptoms.
Contributing factors
A mix of social, psychological and biological factors. People who have lived through abuse, severe loss, unemployment, bereavement or traumatic events are more likely to develop it, and depression can in turn add stress and worsen life circumstances.
Sources
- WHO fact sheet, Depression, published 11 September 2026, read 9 October 2026.
Last reviewed: 9 October 2026. Reviewer: none yet. This page is general education and is not medical advice. Figures are WHO's and may have been updated since.