General information for adults. Not medical or psychotherapeutic advice; not a substitute for examination, diagnosis or treatment.
More than a sad day
Depression is a mental health condition. Persistently low mood or a loss of pleasure and interest are central features. It differs from ordinary changes in mood. [2]
What can it feel like?
Energy, concentration, sleep and everyday life can also be affected. Some people describe emotional emptiness; others struggle with familiar tasks. Experiences differ from person to person. [1]
Why is there no simple explanation?
Biological, psychological and social influences can interact. A stressful event may play a role, but depression can also occur without an obvious trigger. General patterns do not automatically explain an individual person’s experience. [1][2]
What is a depressive episode?
The term describes a period of depressive symptoms. Some people experience one episode; symptoms can also return or persist. A general description cannot predict an individual person’s course. [1]
What can this overview tell you?
It explains terms, but cannot tell whether you or someone else has depression. Diagnosis considers symptoms, duration and their impact together. [3] For personal health questions, consult an appropriately qualified professional.
READ FURTHER & CHECK THE SOURCES
Sources and context
How should I interpret these sources?
Source notes identify the provider, their use in this article and known limitations. The source-comparison date below is not the original publication date. No update date is assumed where none is available. General findings cannot automatically be applied to an individual; independent medical review of this draft is pending.
- IQWiG · InformedHealth.org: Depression ↗
Provider / domain: www.informedhealth.org
Plain-language overview. Used for terminology, symptoms and course.
- WHO: Depressive disorder (depression) ↗
Provider / domain: www.who.int
International overview. Used for the distinction from mood changes and contributing factors.
- German National Clinical Practice Guideline · Chapter 2 ↗
Provider / domain: www.leitlinien.de
German-language clinical guideline. Used for diagnostic assessment and the limitations of questionnaires.
Research and source comparison: 29 October 2026. Prepared with AI assistance. Editorial responsibility: Mario V.W.B.R. Obst. Independent medical expert review is pending. Independent medical expert review has not taken place.