Depression (clinically called major depressive disorder) is one of the most common health conditions in the world. It is more than feeling sad or having a hard week. Depression is a persistent change in mood, thinking and energy that lasts at least two weeks and makes everyday life harder. The encouraging news is that depression is highly treatable, and most people who get support feel significantly better.
Common signs and symptoms
Depression looks different from person to person, but clinicians look for a pattern of symptoms that are present most of the day, nearly every day:
- Low, empty or hopeless mood (in teens this may show up as irritability)
- Loss of interest or pleasure in things you used to enjoy
- Changes in sleep — sleeping much more or much less than usual
- Changes in appetite or weight
- Fatigue and low energy, even after rest
- Difficulty concentrating, remembering or making decisions
- Feelings of worthlessness or excessive guilt
- Moving or speaking more slowly, or feeling restless
- Thoughts of death or suicide
Physical symptoms such as aches, headaches or digestive problems are also common and sometimes are the first thing people notice.
What causes depression?
There is no single cause. Depression usually arises from a combination of factors: genetics and family history, differences in how brain circuits regulate mood and stress, ongoing stress or difficult life events (loss, isolation, financial strain, relationship problems), medical conditions such as thyroid disease or chronic pain, certain medications, and substance use. Depression is not a personal weakness or a character flaw, and it is not something a person can simply "snap out of."
How it is diagnosed
A primary care clinician, psychiatrist, psychologist or other licensed professional can assess depression. They will usually ask about your symptoms and how long they have lasted, review your medical history, and may use short questionnaires such as the PHQ-9. Sometimes blood tests are ordered to rule out physical causes like an underactive thyroid or vitamin deficiency.
Treatment options
Psychotherapy is effective for mild to severe depression. Cognitive behavioral therapy (CBT), behavioral activation and interpersonal therapy (IPT) have strong research support. Medication, most commonly SSRIs or SNRIs, can help especially for moderate to severe depression and often works best combined with therapy. Antidepressants typically take 4–8 weeks to reach full effect, and should never be stopped suddenly without talking to a prescriber. For depression that has not responded to several treatments, options such as transcranial magnetic stimulation (TMS), esketamine and electroconvulsive therapy (ECT) are available through specialists.
Self-care that supports recovery
- Keep a regular sleep and wake time
- Plan small, achievable activities each day — even a short walk counts
- Stay connected with at least one supportive person
- Limit alcohol, which worsens mood and sleep
- Be patient: recovery is usually gradual, with good and bad days
Medical disclaimer: This article is for general educational purposes and is not a substitute for professional medical advice, diagnosis or treatment. Always consult a qualified health professional about your situation. See our full disclaimer.