Self-guided library
Depression
In short
Depression is a persistently low or empty mood, or loss of interest in things you used to enjoy, most of the day nearly every day for at least two weeks, to the point it affects daily life. It is treatable (NIMH).
Depression is more than feeling sad. NIMH describes it as a persistently low or empty mood, or loss of interest in things you used to enjoy, most of the day nearly every day for at least two weeks — to the point that it affects sleep, eating, work, and relationships. It is common, and importantly, it is treatable. The earlier treatment begins, the more effective it tends to be.
Common forms
NIMH describes two common types. Major depression involves low mood or loss of interest most of the time for at least two weeks. Persistent depressive disorder (also called dysthymia) is a lower-grade depression that lasts much longer — usually at least two years.
Depression can also take specific forms, including seasonal affective disorder, which follows a seasonal pattern, and perinatal depression, which can occur during pregnancy or after childbirth and is more than the temporary "baby blues."
Why activity matters: behavioral activation
Depression often creates a loop: low mood leads to doing less, doing less means fewer rewarding experiences, and that pushes mood lower still. Behavioral activation (BA) is a practical, evidence-based approach that targets this loop directly by gradually rebuilding activity.
A common BA method, used in NHS self-help workbooks, is to plan three kinds of activities each week: routine (daily basics), necessary (things that cause problems if neglected, like bills or appointments), and pleasurable (things you value or enjoy). The goal is to act first and let mood follow, rather than waiting to feel motivated.
BA is recommended in UK NICE guidance, and a 2014 meta-analysis of 26 randomized trials (Ekers and colleagues) found it more effective than control conditions and broadly comparable to other established therapies for depression.
Treatment options
Most people with depression benefit from treatment: talk therapy (such as CBT or behavioral activation), medication, or a combination. A healthcare provider can help you weigh the options based on your symptoms and history.
How depression connects
Key points
- Depression is low mood or loss of interest most days for two weeks or more — and it is treatable.
- Major depression and persistent depressive disorder (dysthymia, lasting 2+ years) are the two common types.
- Behavioral activation rebuilds rewarding activity to break the low-mood-and-withdrawal loop.
- Therapy, medication, or both help most people; earlier treatment works better.
When to seek help
Talk with a healthcare provider if you have symptoms most of the day, nearly every day, for at least two weeks. If you or someone you know is having thoughts of suicide, call or text 988 in the U.S., or call 911 in an emergency.
Frequently asked questions
What is depression?
Depression is a persistently low or empty mood, or loss of interest in things you used to enjoy, most of the day nearly every day for at least two weeks, to the point it affects daily life. It is treatable (NIMH).
What is the difference between major depression and persistent depressive disorder?
Major depression involves symptoms for at least two weeks; persistent depressive disorder (dysthymia) is a lower-grade depression that lasts much longer, usually at least two years (NIMH).
Does behavioral activation work for depression?
Yes. It is evidence-based and recommended in UK NICE guidance; a 2014 meta-analysis of 26 randomized trials found it more effective than control conditions and broadly comparable to other established therapies (Ekers et al.).
References
- 1. NIMH — Depression
- 2. NHS (ELFT) — Behavioural Activation self-help workbook (PDF)
- 3. Ekers et al., 2014 — Behavioural Activation for Depression: meta-analysis (PLOS ONE)
Further reading
This article is for education and general wellness only. It is not medical advice, diagnosis, or treatment, and does not replace care from a qualified professional. If you are in crisis, call or text 988 (U.S.), or call 911.